SB 14-01-31; RV-6, 7, 8

[GLPalinkas]

Hi Scott I'm probably being blind ;) but having downloaded the Section 5 http://www.vansaircraft.com/pdf/revisions/RV-ALL_Section-5.pdf I cannot see a section on "Removal of Rivets"?

I am sure from your post it is there - any chance of a page / section ref please?

+1 Andy. I did find a section titled "drilling out rivets" and it quoted from an Alcoa manual about how sometimes it's not necessary.

Scott, please let us know where the new information on rivet removal is located. I've been drilling out rivets, gently, for a long time. Heads removed and body punched out. If this has changed, we early builders need to know.

[rvbuilder2002]

Hi Scott I'm probably being blind ;) but having downloaded the Section 5 http://www.vansaircraft.com/pdf/revisions/RV-ALL_Section-5.pdf I cannot see a section on "Removal of Rivets"?

I am sure from your post it is there - any chance of a page / section ref please?

oops, my bad.
It turns out the detailed rivet removal update hasn't gone public yet (I thought it had) and will be released at the same time the update to the RV-7 and 8 plans is released (should hopefully be by the end of the week).
I will try and remember to post a link to it in this thread when it is released.

[tweiss]

oops, my bad.
It turns out the detailed rivet removal update hasn't gone public yet (I thought it had) and will be released at the same time the update to the RV-7 and 8 plans is released (should hopefully be by the end of the week).
I will try and remember to post a link to it in this thread when it is released.

I don't want to drift this thread, but updated plans for the -7 & -8?
Do we watch Van's website for this info?
Thanks
Tom

[swisseagle]

My buddy checked his plane:

RV-7
O-320, Sensenich FP
mild acro
35% on grass
1350h

Relief notches
Cracks left and right top :eek:

[LifeofReiley]

Scott, (rvbuilder2002)

After the testing was performed before the SB was written, what is the theory for the cause of the cracking that was found? :)

[CaptainQwyx]

Looks like the HS is getting a bit of a redesign. (For reference, emp. kit 7-4286 ordered on 1/13/14 and delivered on 1/20/14.)

My pick list has no mention of HS-404 and HS-405 at all, instead it lists "HS-00006" and "HS-00005" respectively, both back-ordered. However the included full-size instructions and plans (Section 6: 7sbr2 6/13/11, DWG 3 R1 1/7/02) still refer to the original part numbers.

When I called the factory last week to report inventory complete (minus a single pop-rivet) and ask about the b/o'ed parts, they said it was a redesign, should be available late-Feb. (with new plans/drawings) and start with the VS instead.

I'm still in the middle of a practice kit anyway so no worries just yet. So I guess if your kit is as new as mine, no need to order the SB pieces yet.

[Mike S]

FYI.

Link to an old thread that may come in handy.

http://www.vansairforce.com/community/showthread.php?t=23223

[Dave H.]

RV-6A built in 2000
3rd owner
430 TT
0-320 FP Wood, cruise pitch
No acro
No grass - all pavement
Always hangared
No cracks
Full height web - no notches
NOT happy with the workmanship found in the in the HS front spar area, and may have the reinforcement done per SB even if no cracks appear in the future.

Question: I am NOT the builder. Is it legal for me to sign off that I did the inspection per SB?

-Dave
SoCal

[Mel]

Question: I am NOT the builder. Is it legal for me to sign off that I did the inspection per SB?
-Dave
SoCal

Yes. You can sign off the SB inspection. You may NOT sign off a condition inspection unless you are an A&P.

[Rocket Man]

RV-6 serial number 23519 (1994)
1143 hours
O-360 A1A
Two blade Catto prop
Very limited acro
99% pavement
NO CRACKS
Phew!

[jroser]

2003 RV6A
600tt
Grass and pavement
2nd owner
No cracks
No notches
Will monitor each condition inspection.


John

[BlackhawkSP]

I removed the fairings today and checked on mine and a friend's RV Super 8's (One an IO-540 the other an O-540). One has 100 ish hours on the airframe, mine had 570.5 hours on the hobbs as of today and NO CRACKS.

Another Super 8 on the north side of Indy though, had a 3/4 inch crack on one side, and he says that he will be redoing the whole H.S.. Bummer, but it's nice that Van's is getting the word out and a fix that will seriously beef up the area in question. It's also good to know that Van's holds their customers safety as a high priority.

[Edwardoc]

RV-8 SN 80366 Horz Built 1997 1st Flt Mar 2006
600 hours
Superior IO 360
Acro and formation, Lots of Grass operations
NO CRACKS:)

[Snowflake]

The -7 HS has the slot, at least mine did, but the -8 HS does not.
Early -7 non-prepunched kits did not have the slot. My kit came with prepunched skins, non-punched spars. DWG3 (not 3PP) has no mention of the notch.

I wonder if the SB could have been a bit more selective in defining on which aircraft the cracks are occurring. So far there are no reports of a crack where the slot is absent, at least not that I have read.
I thought so too, but as of today I just found out that my hangar mate's -6 has at least one crack. No notches. This is a -6 that has given a fair bit of transition training however, so it may not be completely representative of the fleet.

[JonJay]

Not necessarily Jon...

I agree that there has been a lot of conjecture here on VAF, but that doesn't mean the development of the modification was based on that.

A detailed CAD model and FEA (Finite Element Analysis) was done on the Horizontal Stab. after the problem was detected. The mod. was developed based on those results, and the knowledge that people will have to be able to successfully install it as a retrofit.

).

Thanks Scott. That is very reassuring.
Do you have any theories as to what is actually causing this?
We have relatively low time machines that have never seen any rough duty with cracks and at the same time high time high g acro planes with no cracks. It is baffling....

[boomer]

2011 RV-8 QB
170 hours
Frequent acro, no grass strips
Had notches on top
No cracks.

-John

[N804RV]

...A detailed CAD model and FEA (Finite Element Analysis) was done on the Horizontal Stab. after the problem was detected....

Was there any specific mechanism or variation in assembly attributable to these cracks?


... One thing to consider before doing this... The bolt connections that attach the stab to the fuselage are just as important as any of the rivets that need to be removed are. Do you know for certain that when you drilled those holes, they were drilled exactly perpendicular to the parts involved. Are you confident, that you can accurately match drill, from below (in a very limited work space), to have a good close clearance fit between the fuselage and the new stabilizer?

Given this, would it be prudent for someone who has yet to skin his HS to go ahead and complete the SB modification? Or, is it recommended to build per original plans and then only complete the SB modification if cracks are later discovered?

[bjdecker]

Scott, (rvbuilder2002)

After the testing was performed before the SB was written, what is the theory for the cause of the cracking that was found? :)

Echoing Mr. Reiley, Scott - what's the root cause, or theory behind this problem? Secondly, what's the FMEA show if this is left unresolved?

[Snowflake]

For the Canadian RV owners... Note that repair will require reporting to, and possible inspection by, Transport Canada. See CAR 549.23, specifically the opening paragraph and the Information Note at the end.

http://www.tc.gc.ca/eng/civilaviation/regserv/cars/part5-standards-549-sub-a-1785.htm
549.23 Design Changes and Repairs

[Design changes and repairs affecting structural integrity, geometry, performance (e.g. change of c.g. limits) and maximum permissible take-off mass will require an inspection by a DOT representative,and may invalidate the Special Certificate of Airworthiness for amateur-built aircraft. Following a design change or repair:]

(a) A new Weight and Balance Report and Climb Test Report may be required,

[(b) Changes or repairs shall be annotated in the Aircraft Technical Records, including the Journey Log book; and]

[(c)] The Minister may request a new Special C of A application or inspections.

[Information Note:

[(a) Changes which will invalidate the Special C of A for amateur-built aircraft, and require a new Weight and Balance Report and Climb Test include:

[ (1) A change in the type or model of the engine. This does not include engine changes within the same series.

[ (2) A change resulting in a mass (weight) exceeding the maximum permissible stated on the special C of A for amateur-built aircraft.

[ (3) An initial change in landing gear from wheels/skis to floats or floats to wheels/skis.

[ (b) A change from wheels to skis or skis to wheels will only require an amendment to the Weight and Balance report.

[ (c) Changes which will require an inspection by a DOT representative include:

[ (1) Any change or major repair affecting structural integrity; and

[ (2) For aerobatic aeroplanes, changes to control surfaces.]

(Change 549-1 (93-06-30))

(Amendment 549-2 (96-04-01))

[Scott Hersha]

2008 RV8 (2007 Kit)
500 TT
O-360/188HP
Whirlwind CS Prop
One LSI EI/ one MAG
Frequent acro / some grass
No notches
No cracks

[g4mech]

RV7 s/n 71036 680 hrs
O360 FP
light acro
Paved and dirt
Tow bar
No cracks with notches
New owner was happy!

[GLPalinkas]

I inspected my HS today per the SB. I also helped check another builders RV-6. Dave Cook's RV-6 had no cracks either.

My -6
RV-6 Started 1998
Flying since Oct 2011
250 hours
O-360 A1A Fixed Pitch Sensenich
Limited Acro
Grass strips when I can
No notches, not on plans
No cracks

Dave's -6
RV-6 Flying for 7 years
350 hours
O-360 Mattituck
No acro
Some grass strips
No notches, not on plans
No cracks

The photos show what I originally saw. I/WE DID CLEAN THE PAINT FROM THE AREA WITH MEK, and THEN EXAMINED THE AREAS WITH A BRIGHT LIGHT AND MAGNIFYING GLASS.

I believe as Danny King and others stated, some RV'ers may not be looking hard enough.


One section of my HS (and yes, I wish I had done a better job of setting some of the rivets.... and stopping the overspray)

http://i62.tinypic.com/2mxr97l.jpg

Dave's RV-6

http://i59.tinypic.com/15dpbnr.jpg

[AlanNZ]

So from New Zealand 2 x RV7a's @ around 300hours each. No problems found with inspection. The comment was made to me that this may effect tail draggers worse than trikes?

Interested on what you guys find.....

[posterman]

RV6A #24567
450 hrs +/-
pavement only
no acro
0360A1A
Fixed pitch
No Cracks

One other RV6A on field and RV7A also no cracks.

[rvbuilder2002]

It has been asked "Are there any theories of the cause."

Yes!
One, is that it is dependent one what primer the builder used :D
(Sorry, couldn't resist).

In reality, it is only guessing why one aircraft with only 500 hrs has a crack, and another with 2000 hrs does not. As I mentioned previously, there are a bunch of factors that could influence this, so there is no way to pin it down to one or two specifics. The proper way to look at it is that with as high of an occurrence percentage there is, the structure, as currently designed doesn't have enough margin to deal with that many variables.

A crack failure like this is the result of cyclic loading. This is more difficult to design for than pure load capability. It is why company's like Boeing spend tons of money doing long term load cycle testing, such as fuselage pressure cycles, and load/unload cycles of wings. etc.

This sort of thing is more difficult to design for than just handling the pure limit and ultimate loads. That is why Boeing has to do cyclic testing... to prove that the airframe has a load cycle life of at least X amount of time. Unfortunately, Van's isn't a company of the size that could afford to do that type of testing. But then again, neither is Beech, Cessna, or any of the other big names in GA. They have all had major (much more so than this) mods on different aircraft as the result of time in service.

Fortunately, there are tools available that can help. Without going into a high level of detail, the FEA showed that there is an elevated point load right at the location the cracks occur. This is because of a number of factors but in simplest terms it is this.
Think of any "C" channel load member as being stiffer than just a plain web by it self. In the case of the stab. spar, we have a c channel at the center of the spar (the spar web with top and bottom angles), and a c channel for the spar in the L & R panels. These two c channels are joined by a narrow zone where one flange of the top and bottom angles has ended but the flanges of the span wise spar channels has not yet begun. This should not be considered a weak point... it has proven more than strong enough to carry the loads. What it does, is make that point slightly less stiff than the surrounding structure. That means it will flex just a bit more each time it goes though a load/unload cycle. With enough time/cycles, this is what causes the crack. Many of the other factors already discussed do have an influence (edge finish quality, etc.), but the bottom line is it appeared the design margin was a bit to small.
So what does the modification do? In simple terms, it adds stiffness to this slightly less stiff zone, and helps transfer the loads well out into the stiffer zones (the center spar area, and the left and right panel areas). This was substantiated with the FEA model.

Yes there is a kit modification underway. New builds will use the same type of doubler parts as are being used for the retrofit. There are new ribs going into production that will accommodate the thickness change of the spar. As already mentioned, builders working on an Emp kit should just work on other components. By the time you get to the H stab, the parts and updated plans and manual will be available.

[wirejock]

Yes there is a kit modification underway. New builds will use the same type of doubler parts as are being used for the retrofit. There are new ribs going into production that will accommodate the thickness change of the spar. As already mentioned, builders working on an Emp kit should just work on other components. By the time you get to the H stab, the parts and updated plans and manual will be available.

Scott
Thanks for keeping us posted.
Do you know if the new ribs will eventually be parts in the SB kit? If I read correctly, they come out. It makes sense to put new ones in that are sized to fit.
I'm going to wait to decide on SB kit or new HS. Since I'm working on wings, there's plenty of time to let things settle out.

[pvalovich]

To RVBuilder2002: After years of SB inactivity, why have there been two SBs over one weekend?

What are you guys hiding?

[Kyle Boatright]

To RVBuilder2002: After years of SB inactivity, why have there been two SBs over one weekend?

What are you guys hiding?

Wow.

I'm frustrated too - especially since a lot of people probably jumped through hoops to inspect their HS, only to come home and learn of another SB in the same general area. But c'mon man.

I figure Van's had two option. Let the word out that SB's are imminent and let 8000 builders stew over rumor and innuendo for days or weeks, OR, keep it quiet, then rapidly develop and release the SB's.

The latter is probably a better choice.

[LettersFromFlyoverCountry]

I've never heard of removing rivets without drilling them out. I know Van's hasn't updated Section 5.yet but I assume they're not inventing the process. Is anyone familiar with this distinction?

Also, having removed my elevator to facilitate inspection, I reinstalled it just in time to come home and see the new SB. Time to invest in a boroscope, I guess.

[LifeofReiley]

RV6's RV7's RV8's have gone thru A&P, IA & Builder Condition Inspections for how many years? The factory aircraft have gone thru inspections how many times. And in ONE weekend, we're slammed with TWO SB's. What is up with Van's here? Not of business character for sure. :mad: Heck, before we get SB #3 this week on the VS, just send us all a new redesigned tail kit and be done with it! Sure would protect OUR investment.

[Snowflake]

I've never heard of removing rivets without drilling them out. I know Van's hasn't updated Section 5.yet but I assume they're not inventing the process. Is anyone familiar with this distinction?

I think I know what Scott was referring to... On page 5 of the PDF he linked to, there's a page of graphics describing the riveting process. At the bottom of that page, near the center, is a set of graphics showing rivet removal. The process described there is to drill the rivet only far enough to snap off the head, then use a punch to drive out the remaining shank.

This as opposed to just drilling though the whole rivet, which is what many people think of when one says "drilling out rivets".

[Caveman]

RV-7 Tipper
2006 vintage tail kit
Flying since October 2008
350 hours
4 relief notches present
195 hp IO-360-m1b
Hartzell BA CS prop
95% pavement
occasional gentleman's acro
No cracks... yet
Bogert tow bar most of the time

Planning to keep flying and inspecting at each oil change until I'm comfortable with the repair process.

[Snowflake]

RV6's RV7's RV8's have gone thru A&P, IA & Builder Condition Inspections for how many years? The factory aircraft have gone thru inspections how many times. And in ONE weekend, we're slammed with TWO SB's. What is up with Van's here? Not of business character for sure. :mad: Heck, before we get SB #3 this week on the VS, just send us all a new redesigned tail kit and be done with it! Sure would protect OUR investment.

To be fair, the issue with cracks in the spar near the eyebolts was raised here on VAF many months ago and discussed extensively. Kudos to Vans for raising the awareness by making it a Service Bulletin, but it is definitely not a "new" issue. I'm glad to see that Vans has looked into it in more detail, and probably with more FEA to zero in on the weak points as well.

[LifeofReiley]

To be fair, the issue with cracks in the spar near the eyebolts was raised here on VAF many months ago and discussed extensively. Kudos to Vans for raising the awareness by making it a Service Bulletin, but it is definitely not a "new" issue. I'm glad to see that Vans has looked into it in more detail, and probably with more FEA to zero in on the weak points as well.

To be fair... Van's needs to come clean with the folks that spent their hard earned money on a kit, to learn that these issues have been known about and researched but not forwarded to builders and owners. We all can help with inspections etc... but an unknown blast of surprise SB's really sucks bigtime. :mad:

[N804RV]

...A crack failure like this is the result of cyclic loading.

.... As already mentioned, builders working on an Emp kit should just work on other components. By the time you get to the H stab, the parts and updated plans and manual will be available.

Thanks! That answers my questions.

[rvbuilder2002]

I think I know what Scott was referring to... On page 5 of the PDF he linked to, there's a page of graphics describing the riveting process. At the bottom of that page, near the center, is a set of graphics showing rivet removal. The process described there is to drill the rivet only far enough to snap off the head, then use a punch to drive out the remaining shank.

This as opposed to just drilling though the whole rivet, which is what many people think of when one says "drilling out rivets".

Actually there is a little more to it than that.
It is not earth shaking new info, but it can make a big difference in avoiding messing something up.

Wait till the update comes out. It will be very clear.

[Mark Burns]

I pulled the HS off this evening. Took all of about 2 hours.
For $15 and a few evenings work this SB is really not a big deal.

Something similar in the "certified" world would be very expensive!

Seems strange to see One Charlie Mike without her tail feathers again.

http://i1133.photobucket.com/albums/m599/mabbmbcb/934ebb2f-46d8-4c67-a7f7-969e872b0b3a.jpg


Data Point: The HS will fit into a Subaru Crosstrek ;)
My RV has a Lycoming! In case you were wondering.

http://i1133.photobucket.com/albums/m599/mabbmbcb/5b4aa35a-e11e-4a08-b5af-9c6d15808be1.jpg

I'm taking the HS home to the garage to do the work. It's where I built the airplane. It's heated and has good lighting.

I'll post about the progress later.

Mark

[rvbuilder2002]

To be fair... Van's needs to come clean with the folks that spent their hard earned money on a kit, to learn that these issues have been known about and researched but not forwarded to builders and owners. We all can help with inspections etc... but an unknown blast of surprise SB's really sucks bigtime. :mad:

-d-,
Leaping to a lot of conclusions there aren't you?

What would your response have been if it was announced 5 weeks (or so) ago when it was first discovered, but no fix was developed.
You probably would have been complaining about why would we notify about a problem and not have a fix for it:rolleyes:
I think 5 weeks is pretty darn good.

Yes, the elevator one has been know about for a bit longer, but I am only aware of 3 or 4 airplanes (out of a lot that were inspected) that had the problem. And it doesn't even require removing a fairing or inspection cover to check. Just grab a flash light and look!

I guess I should have learned by now that there are people in the world that wont be happy regardless what you do.
Mods feel free to delete this, because it is likely to go no where good... just had to vent.

I'm done here.

[JonJay]

What am I missing. Vans discovered a problem, identified it's likely cause, and engineered and documented a repair. Not sure what else they can do.
That certainly meets my expectation.

[Bob'sRV6A]

Couple of RV builders I know will not do stalls anymore after observing their HS during full stalls. Lots of "loading/unloading"--maybe more so than aerobatics, or hard landings, tri-gear, or tail-dragger.
Perhaps Vans Demo planes do the most stalls per flight hour? Even though someone does lots of acro, maybe they do few stalls. And maybe someone who does no acro does more stalls?
Just my 2 cents.

[LifeofReiley]

-d-,
Leaping to a lot of conclusions there aren't you?

What would your response have been if it was announced 5 weeks (or so) ago when it was first discovered, but no fix was developed.
You probably would have been complaining about why would we notify about a problem and not have a fix for it:rolleyes:
I think 5 weeks is pretty darn good.

Yes, the elevator one has been know about for a bit longer, but I am only aware of 3 or 4 airplanes (out of a lot that were inspected) that had the problem. And it doesn't even require removing a fairing or inspection cover to check. Just grab a flash light and look!

I guess I should have learned by now that there are people in the world that wont be happy regardless what you do.
Mods feel free to delete this, because it is likely to go no where good... just had to vent.

I'm done here.

Scott,

Not trying to pound on you! You answer randomly here when questions are asked. Van's needs to speak up and let us know (the maufacturers of the aircraft) what is going on. Take polls, send emails etc.. Just don't throw out two SB in a weekend and expect us all to be okay with it. :) Help us help you.

[Mike S]

Scott,

Not trying to pound on you!

Maybe not your intent to "pound" on Scott and Vans, but it sure sounds like what you are doing to me.

------ in ONE weekend, we're slammed with TWO SB's. What is up with Van's here? Not of business character for sure. :mad: Heck, before we get SB #3 this week on the VS, just send us all a new redesigned tail kit and be done with it! Sure would protect OUR investment.


... Van's needs to come clean with the folks that spent their hard earned money on a kit, to learn that these issues have been known about and researched but not forwarded to builders and owners. We all can help with inspections etc... but an unknown blast of surprise SB's really sucks bigtime. :mad:

From what I can see looking at this thread, Scott has been very open with information, and has tried to deal with the issue in a manner that is well balanced and thought out. The explanation of the process arriving at the SB (computer modeling etc) shows that this is well thought out and engineered solution. This type of action does not happen overnight-----takes time to develop.

What am I missing. Vans discovered a problem, identified it's likely cause, and engineered and documented a repair. Not sure what else they can do.
That certainly meets my expectation.

Well said Jon.

[Andy Hill]

Reiley

I think you're giving Vans, and Scott especially, too much of a hard time and it would be a shame if Scott decided not to post as a result.

The 2nd SB is not news at all... been well trailed on here as discussed above.

In each case Vans has done a good job in not just alerting the problem, but also designing and starting production of a fix. Yes - we all are asking more questions (some of which are probably not possible to answer), but I cannot see how that could be avoided.

Scott - thanks for the updates and will await the "drill-less rivet removal" technique :D

[RV7DES]

New Zealand RV7
600h
Lots of Aerobatics,
Occasionally grass strips
Clear cracks on both sides.

In order to take out of hanger I need to lift the tail onto a tow bar. I have often used the horizontal stabiliser to do this, and wonder if this could a contributing factor to the clear cracks. In hindsight I should use the spike.
Have already removed the horizontal stabiliser and will not fly until I have fitted SB 14-01-31

Will add photos shortly if I can

[RV10inOz]

Couple of RV builders I know will not do stalls anymore after observing their HS during full stalls. Lots of "loading/unloading"--maybe more so than aerobatics, or hard landings, tri-gear, or tail-dragger.
Perhaps Vans Demo planes do the most stalls per flight hour? Even though someone does lots of acro, maybe they do few stalls. And maybe someone who does no acro does more stalls?
Just my 2 cents.

And accelerated stalls.

We have a video in the APS course of George Braly doing testing on the T34 when the FAA were about to ground the fleet. He had strain gauges all over this thing and was replicating flight loads. GAMI subsequently came up with what I still consider to be the most brilliant solution to any difficult problem I have seen to date.

But the funny part was he collected some video of the tail feathers doing accelerated stalls at 117kts. :eek::eek::eek:

After seeing this video you will never want to do one ever again! And I mean it.

rvbuilder2002
Imagine the same thing from Cessna....timely, $10 fix?

Vans are at the pinnacle of customer service in the industry, along with a small group of others I can think of, but it is very small. Be grateful for what we have, it does not get better, trust me. Tried Lycoming or TCM? :cool:

[Robski]

I'm done here.

All of us (except maybe one) hope that's not permanent.

As for Van's response to the issues - try getting any on-going support from many other kit suppliers, let alone for discontinued models (RV6). Some people don't appreciate when they are well off.

[ILikePike]

Rvbuilder2002,
Your insight is very appreciated please do not hesitate to post. Your input carries the most weight with me. I wish the complainers would go work on their car or something. They should stay away from airplanes, airports, and this forum.

Would you be willing to comment on the relief notches vs normal smoothed radius as it relates to FEA?

[GLPalinkas]

I hope Scott continues to provide what he knows here on this and many more subjects.

In fairness, if the fact that the HS issue was just discovered and 5 weeks later a SB was engineered and put into effect was known earlier it would have eased a lot of minds. Maybe the SB should contain that information.

Scott, sincerely, THANK YOU for what you do on VAF to help builders.

[LettersFromFlyoverCountry]

It goes without saying that we appreciate Scott's efforts.

That said, it'd be great if a separate thread could be set up for the flame war portion of this discussion so that those of us trying to get solid technical information don't have to wade through the noise. This is pretty serious business.

[pa38112]

2004 RV6A
420 Hr. TT
O-360-A-1-A
FP Stensenich
50% grass
some Acro
No relief notch
No cracks !!

[Captain Avgas]

Rvbuilder2002,
Would you be willing to comment on the relief notches vs normal smoothed radius as it relates to FEA?

Step 8 of the relevant Service Bulletin reinforcement instructions states as follows:

"Inspect the corners at the inboard end of the top and bottom fwd spar flanges on the left and right spar halves for the presence of relief notches as depicted in Figure 3.

If notches are not present, use a round file to add relief notches (first refer to the following step... adding a missing notch may be done in conjunction with removing a crack). This will require trimming the skin slightly as shown in Figure 2 to gain access for the file".

I think that's your answer.

I think it also addresses concerns raised by a number of posters that the relief notches might in fact be precipitating the problem.

[DeltaRomeo]

Let’s stay on topic in this thread with the service bulletins at hand.

If conversation starts dissolving into a flame/speculation wars, I’ll ban accounts permanently, regardless of the number of posts or importance you feel you might have here. This online space isn’t for talking heads on TV yelling conspiracy theories; you’re a guest in MY virtual living room.

Van’s, you rock. Thanks for looking over our shoulders here and keeping us informed.

It is very much appreciated.

I know it is special that you take the time, and make the effort, to chime into this site and help us out.

Now, back to complying with the service bulletins…

v/r,
dr

PS: No cracks on my HS. Inspecting elevators next.

[DeltaTango]

Inspected my -8 today and found no cracks. Flying 10 years with a little over 800 hrs and mild acro. Also inspected a friends -8 and found no cracks in his either. Don't know the exact time in service. He has at least a 200 hours also with mild acro. Going back today to check the elevator SB.

[pa38112]

When I look at the photos of the planes with cracks compared to mine without cracks, one thing that jumps out is the radius of the bend. On my plane the bend tucks tightly into the corners. In the photos that show cracks most of them seem to show the piece under some pre-load as if the tab were being pulled tight by the rivet.

[gvouga]

2008 RV7 (Emp Kit from 2003 - prepunched)
980 Hr. TT
Superior XP-360
Hartzell BA
some grass
some Acro
relief notch
No cracks

[LettersFromFlyoverCountry]

My question is on the subject of the relief notches and the early kits (the 2/2001 DWG 3) that did not show them. I don't have the cracks, but I don't have the notches, either. Would that influence whether I should wait for the cracks to appear to take some corrective action?

[bret]

And accelerated stalls.

We have a video in the APS course of George Braly doing testing on the T34 when the FAA were about to ground the fleet. He had strain gauges all over this thing and was replicating flight loads. GAMI subsequently came up with what I still consider to be the most brilliant solution to any difficult problem I have seen to date.

But the funny part was he collected some video of the tail feathers doing accelerated stalls at 117kts. :eek::eek::eek:

After seeing this video you will never want to do one ever again! And I mean it.

rvbuilder2002
Imagine the same thing from Cessna....timely, $10 fix?

Vans are at the pinnacle of customer service in the industry, along with a small group of others I can think of, but it is very small. Be grateful for what we have, it does not get better, trust me. Tried Lycoming or TCM? :cool:



Do you have a link to said video? thanks. Bret

[rvmills]

Maybe not your intent to "pound" on Scott and Vans, but it sure sounds like what you are doing to me.

From what I can see looking at this thread, Scott has been very open with information, and has tried to deal with the issue in a manner that is well balanced and thought out. The explanation of the process arriving at the SB (computer modeling etc) shows that this is well thought out and engineered solution. This type of action does not happen overnight-----takes time to develop.

Well said Jon.

I bought Darryl a Snickers bar?he's not him when he's hungry! :D (He's a good dude, lots of passion?now back to the OP!)

Do you have a link to said video? thanks. Bret

Yes David, please do tell! Hoping its not proprietary APS class subject matter, and available for the greater good!

Cheers,
Bob

[LifeofReiley]

I bought Darryl a Snickers bar?he's not him when he's hungry! :D (He's a good dude, lots of passion?now back to the OP!)

Cheers,
Bob

Hey Bob,

Man I really needed that Snickers Bar too... Thanks! :) Praying for a good day with no SB's. :eek:

[tullow]

For your stats -


RV7,
IO360,
FP Sensenich prop
200 hrs. total
95% grass ops.
Notches there,
NO cracks, so I'll just sign it off and include the inspection in my annual

Mike Greene

[Robert Anglin]

Looked at this for a long time as I am a little slow and like to think things over before sticking my foot in my mouth. This is not that big a deal if you look at the history of Part 23 aircraft. We have had a lot of Mods. come down the pipe over the years on factory built aircraft. I think post # 278 has more than addressed the issue. For my part I will hold off till the new ribs are ready and do this mod as I have the time to pull the H.S. back off and work in comfort on the bench. The hard part looks to be bucking the rivets of the fish-plates up inside the skins. Yes it will heart, but doable. This is "P.M." on my part, but I sing it off one time and the value of my work and peace of mind are good to go from that point. Mark Borns in post #290 has it going already. Good job Mark. and thanks too you Scott for fading this heat. We may need to buy you more than a single beer, but don't get your hopes up for more than a six-pack. Hope this helps. R.E.A. III #80888

[Bavafa]

It would be great if we can start a poll to compile the data as how many with cracks and perhaps a breakdown of each category with/without notch, high/low hours etc.

Also let me voice my appreciation for both Vans/Scott and DR for providing an awesome service with the timely info and a venue to share them.

[Dan92]

RV-7A
125 hrs.
light acro
lots of grass runways
no cracks

Dan

[RVG8tor]

I would like the thank all those who post information and especially Scott for giving some of the finer details.

I am very interested in the the data so some conclusions might be made. It seems it would serve Van's to know this information as well. I would kindly suggest sending a questionnaire to each registered owner of the effected aircraft then this data could be compiled and studied then perhaps more light might be shed on why some have the cracks and some don't. It might even show that if you don't have a crack you more than likely will not develop a crack.

I think a questionnaire could be made available online, someone told me about a site called "Survey Monkey" or something similar.

The most important thing at this point is to get the word out. I have spoken to at least 3 RV owners that did not know about the SB since they don't regularly view VAF and or Van's Aircraft. So please talk to, phone, email, text, Facebook your RV friends.

Cheers
Plan to have a happy RV day today!

[GaryChatelain]

RV8
1,000 Hrs
200 HP
C/S Prop
No grass
Light Acro
Fat guy in front seat
No Notches
No Cracks

[GreggG]

It has been asked "Are there any theories of the cause."

Yes there is a kit modification underway. New builds will use the same type of doubler parts as are being used for the retrofit. There are new ribs going into production that will accommodate the thickness change of the spar. As already mentioned, builders working on an Emp kit should just work on other components. By the time you get to the H stab, the parts and updated plans and manual will be available.

I just finished my workshop and was planning on starting my RV-8 empennage this week. Would you recommend that I wait for the redesign? Should I start my VS?

I called Van's yesterday to order the parts for SB 14-01-31 and asked about a redesign. The parts lady transferred me to a tech, and he said there wasn't going to be a redesign and to order the SB parts. Now it turns out there is going to be a redesign.

How about SB 14-02-03? Should I order that? Will it be addressed in the redesign?

I am just starting out and this is a little frustrating...

Thanks,
Gregg

[RVJeff]

RV-8
Flying since March 2008
400 hours TT
No Acro (did enough in the Air Force at UPT)
Have notches on my left and right forward spar. I put them there per plans.
My tail kit was purchased in Sep 2000. Can't speak to the RV-7 community,but
Many of my parts were 7/8 parts. So, integration had started.
Great airplane.

And on a separate note.

I used to live in Tacoma Wa while I was building my -8. Stationed at McChord AFB. Like everybody else who builds, I had tons of questions or just needed a real visual on some operation I was about to undertake. I would hop in my truck and take I-5 south for about 2 hours to Vans factory. I always needed extra parts, screws, nut plates, or whatever anyway so down I drove. I would go out back to their hangar and gawk all over their RV-8 to get my visual on what my building dilemma was. That's when I met Scott. Even though he is a very busy man working in their prototype shop and just doing general MX on all their factory demo aircraft, he always had time to answer my questions and lead me AWAY from stray. I am forever grateful. I also got million dollar tech support from Scott Risan who is now general manager of the company. Boy has he moved up! So, to have Scott M on this forum offering his pearls of wisdom and knowledge is priceless. Believe me....

So I am hoping that Scott saying "I am done here", was just him saying he was very tired for the night and just checking out for a rest. Thanks Scott for your input here and thanks for helping me out those years ago in the hangar at work. I have a flying plane because of your inputs. Now on to check my elevators for spar issues. Heck, my annual is about due anyway, so up and at it.

[scsmith]

inspection result, no notch, no cracks

RV-8 s/n 82718

TTSN 289
1st flight Sept 2009

IO-360-A1A
Whirl Wind 200RV prop
mild acro
20% of landings on dirt
hangared

[Neal@F14]

Has anyone found cracks on any RVs equipped with wood or composite fixed pitch props... or composite bladed CS props?

Going thru the reports posted thus far, unless I've missed something, it seems like only those with metal props (both FP and CS) are finding cracks.

[Dave_G]

For the stats...

Early RV-6A (not a prepunch)
First flight in 1996
1000 hrs TT
O-360 with Hartzel CS prop.
No acro
Mostly operated on paved runways
Always use a tow bar.
Turtle wood gear leg stiffeners (anyone thought about cycles from gear leg shimmy?:rolleyes:)
Has relief notches
No cracks

Dave

[rvbuilder2002]

I'm done here.

Didn't mean gone from VAF... just meant done with this thread (I think I have contributed all I can at this point).

Having said that, some have mentioned waiting for the new root ribs.
On a retrofit, the skins are already dimpled. That makes it difficult to properly fit and locate un-drilled/dimpled ribs. Also your would be match drilling from dimpled holes that are slightly over sized (hopefully just from having been dimpled).
Thus, the reason the SB directs to reuse the original ribs.

[Mike S]

Didn't mean gone from VAF...


You have just made a lot of folks who had been holding their breath, breathe again

[Neal@F14]

Turtle wood gear leg stiffeners (anyone thought about cycles from gear leg shimmy?

No, but the "wet dog shake" during engine startup/shutdown idea shaking the tailfeathers, especially the counterweighted elevator tips, in a cyclic manner was brought up by DanH in this thread: http://www.vansairforce.com/community/showthread.php?t=104551&page=25 specifically starting in post #248 and continuing on to the next page, has been making my brain itch. Especially since RVs with metal props seem to do that shake a lot more pronounced than those with wood or composite props.

Note that I'm no aircraft engineer by any means... just insatiably curious.

[Paul Tuttle]

No cracks.
No notches.
Only 50 hrs though.

[scard]

I'm happy to have a little skin in this game. Just inspected mine. No cracks. 0hrs. Lots of aerobatics being moved from one space to another in the shop! I'm looking forward to getting the parts so I can utilize my expertly honed rivet removal skills :). This is going to be an easy couple hour project for those of us that have yet to install the HS. I do feel a bit sorry for those that didn't build their airplanes or otherwise have acquired the skills.

[LettersFromFlyoverCountry]

Didn't mean gone from VAF... just meant done with this thread (I think I have contributed all I can at this point).

Having said that, some have mentioned waiting for the new root ribs.
On a retrofit, the skins are already dimpled. That makes it difficult to properly fit and locate un-drilled/dimpled ribs. Also your would be match drilling from dimpled holes that are slightly over sized (hopefully just from having been dimpled).
Thus, the reason the SB directs to reuse the original ribs.
I think you just showed that you have more to contribute. :) That's pretty important advice right there.

[Paul K]

Im with you Scott! (scard) So glad I am the builder and still have all my tools etc. This shouldn't be a big deal at all! I do think I will wait until either cracks show up or the retro kits are more available and their installation is well documented. Might give me something to do in our really crappy Michigan weather :D

Scott, (rvbuilder2002), I totally understand your position and appreciate your contributions. Please don't let a few spoil it for all the rest of us, the majority who are really appreciative of your input. I will personally buy you a beer at this years Oshkosh get together, it's on me.

[GaryStofer]

No cracks yet.

~298 hrs, Franklin/PZL6A350,
No aerobatics.
Paved runways only.
No pronounced relieve holes,

G

[DEWATSON]

RV8
IO360 with 9/1 compression
350 hours
95%grass runway
mild acro
never over 4.6 G
no cracks

[boomer]

Did a quick spreadsheet of the messages in this thread which gave results of cracks or no cracks. About half way through I stopped logging "no crack" results and only logged those with cracks. I did not notice any data points which stood out in the "no crack" results. There were many high time, acro, no notches in that category.

Here is a Excel matrix of those who reported cracks. I have listed message number from this thread for reference. If you want to give me any missing data, send it to jhbanister@hotmail.com. Be sure to reference your message number.

Msg # Type A? Kit Date Date Completed Total Time Acro? Grass Strip Cracks? Notches?
37 7 A 1400 Y Y N
50 6 2000 1200 Y
58 7 A 955 Y Y Y
74 6 1200 Y Y Y
98 7 850 Y Y Y Y
125 6 560 N N Y Y
144 8 2000 1345 Y Y
162 8 1900 Y Y Y N
164 7 A 635 Y Y
229 6 A 1900 Y Y Y
257 7 1350 Y Y Y Y
297 7 600 Y Y Y

My apologies for the poor alignment. I couldn't figure out a better way to post the spreadsheet.

I also did not list any of the "batch" posts which said something like "we inspected four RV's and one of them had cracks," mainly because there was no meaningful data in the posts. If those who did this want to give me an update in this format, I will include it.



Some things which stand out to me:

1. 50% RV-7's. 33% RV-6's. 12.5% RV-8's. 33% are A models.
2. Lowest time is 560 hours. (many high timers had no cracks)
3. All but one (92%) did acro.
4. No correlation noted with notches.

-John

[boomer]

I just noticed that you can't tell which data fields are blank in my previous post. Here is a second try with "?" in the blank fields.

Msg # Type A? Kit Date Date Completed Total Time Acro? Grass Strip Cracks? Notches?
37 7 A ? ? 1400 Y ? Y N
50 6 ? 2000 1200 ? ? Y ?
58 7 A ? ? 955 Y ? Y Y
74 6 ? ? 1200 Y ? Y Y
98 7 ? ? 850 Y Y Y Y
125 6 ? ? 560 N N Y Y
144 8 ? 2000 1345 Y ? Y ?
162 8 ? ? 1900 Y Y Y N
164 7 A ? ? 635 Y ? Y ?
229 6 A ? ? 1900 Y Y Y ?
257 7 ? ? 1350 Y Y Y Y
297 7 ? ? 600 Y Y Y ?

-John

Did a quick spreadsheet of the messages in this thread which gave results of cracks or no cracks. About half way through I stopped logging "no crack" results and only logged those with cracks. I did not notice any data points which stood out in the "no crack" results. There were many high time, acro, no notches in that category.

Here is a Excel matrix of those who reported cracks. I have listed message number from this thread for reference. If you want to give me any missing data, send it to jhbanister@hotmail.com. Be sure to reference your message number.

Msg # Type A? Kit Date Date Completed Total Time Acro? Grass Strip Cracks? Notches?
37 7 A 1400 Y Y N
50 6 2000 1200 Y
58 7 A 955 Y Y Y
74 6 1200 Y Y Y
98 7 850 Y Y Y Y
125 6 560 N N Y Y
144 8 2000 1345 Y Y
162 8 1900 Y Y Y N
164 7 A 635 Y Y
229 6 A 1900 Y Y Y
257 7 1350 Y Y Y Y
297 7 600 Y Y Y

My apologies for the poor alignment. I couldn't figure out a better way to post the spreadsheet.

I also did not list any of the "batch" posts which said something like "we inspected four RV's and one of them had cracks," mainly because there was no meaningful data in the posts. If those who did this want to give me an update in this format, I will include it.



Some things which stand out to me:

1. 50% RV-7's. 33% RV-6's. 12.5% RV-8's. 33% are A models.
2. Lowest time is 560 hours. (many high timers had no cracks)
3. All but one (92%) did acro.
4. No correlation noted with notches.

-John

[Neal@F14]

Did a quick spreadsheet of the messages in this thread which gave results of cracks or no cracks.

Might want to include propeller type and material the prop is made of too.

I have a strange hunch that we may only see cracks on planes with metal props (both FP and CS) or at least that metal props have a large affect of the probability of these cracks happening. Could be totally wrong too, it's just a hunch. Actually the idea comes from what DanH posted here (http://www.vansairforce.com/community/showpost.php?p=823798&postcount=248), so he gets the credit if this indeed is the triggering cause of these cracks, since the locations have been determined to be points of elevated point load (see Scott's post here: http://www.vansairforce.com/community/showpost.php?p=850457&postcount=278)

EDIT: OK, I've done a quick search for prop type in each plane of Boomer's list above and found:

6 of them are equipped with Hartzell CS props;
3 of them are equipped with Sensenich FP metal props;
1 is currently equipped with a Catto for the past few hundred hours but had something else for the rest of its 1900 hours according to a post by the owner;
1 one has either a Hartzell CS or a Whirlwind CS prop, all I could find was one photo of the plane with the prop spinning so I couldn't really tell for certain which prop it had;
1 was indeterminable what type prop it has.

[wirejock]

Didn't mean gone from VAF... just meant done with this thread (I think I have contributed all I can at this point).

Having said that, some have mentioned waiting for the new root ribs.
On a retrofit, the skins are already dimpled. That makes it difficult to properly fit and locate un-drilled/dimpled ribs. Also your would be match drilling from dimpled holes that are slightly over sized (hopefully just from having been dimpled).
Thus, the reason the SB directs to reuse the original ribs.

Scott
Thanks again.
I have a question about the use of existing ribs in the SB repair.
It looks like HS-0001 spar doubler and HS-0002 rib flange angle are between the spar and
HS-405 main rib. I can't tell the thickness of the doubler but the angle is .040".
Will this added thickness make the rib bind or make the rib/ skin holes difficult to align?
I'm not an engineer pardon if this is a stupid question.

[Nukeflyboy]

2000 RV6
667 hours TT
0-360
Metal fixed pitch Sensenich
<10% grass fields
Bunch of acro, NTX 4.5 G
HS built in 1992
Radiuses fairly large and smooth
No cracks!

Thanks Scott for the good info.

[Mark Burns]

Scott
Thanks again.
I have a question about the use of existing ribs in the SB repair.
It looks like HS-0001 spar doubler and HS-0002 rib flange angle are between the spar and
HS-405 main rib. I can't tell the thickness of the doubler but the angle is .040".
Will this added thickness make the rib bind or make the rib/ skin holes difficult to align?
I'm not an engineer pardon if this is a stupid question.

Scott,
The service bulletin explains it all. You cut off the forward flange of the main ribs.Then use the angle to make new flanges. Done correctly you will have perfect alignment.

Mark

[wirejock]

Scott,
The service bulletin explains it all. You cut off the forward flange of the main ribs.Then use the angle to make new flanges. Done correctly you will have perfect alignment.

Mark

Thanks Mark
I see it now.
Told you it was a stupid question.

[60av8tor]

I do feel a bit sorry for those that didn't build their airplanes or otherwise have acquired the skills.

Yes, this can definitely change your viewpoint on SB. I am still very wet behind the ears (just finishing up the VS on my -10), but I can say that I look at this quite differently now vs. several months ago. I will still get some experienced builders to double check my work when/if I choose to comply w/ the SB, but it is very nice to look at this with the knowledge that I have a workshop set up and working.

Nothing for nothing - I'm sure we have some Bo owners/previous owners - I believe Bonanzas had a similar recurring inspection on the tail?

[jonweisw]

No cracks.

RV-8/N898JW
680 TTSN, completed 7/2004
IO360M1B
WW200RV
rare, mild acro
paved runways only
towbar
no notch

[FA50driver]

1998 RV6
420 Hr. TT
Lycoming O-360
Hartzell CS
some grass
some Acro
relief notch
No cracks

[johnfurey]

2011 RV7 205 hrs
IO 360 M1B WW prop
Mostly Grass Strips
Notches
No Cracks yet but looks like all the material removed by the notches could work against us.

[81270]

You have just made a lot of folks who had been holding their breath, breathe again

Hear hear!

Otherwise no data from me as I am still in build stage (about 90% complete) but will be doing the SB

[BillL]

I just noticed that you can't tell which data fields are blank in my previous post. Here is a second try with "?" in the blank fields.

Msg # Type A? Kit Date Date Completed Total Time Acro? Grass Strip Cracks? Notches?
37 7 A ? ? 1400 Y ? Y N
50 6 ? 2000 1200 ? ? Y ?
58 7 A ? ? 955 Y ? Y Y
74 6 ? ? 1200 Y ? Y Y
98 7 ? ? 850 Y Y Y Y
125 6 ? ? 560 N N Y Y
144 8 ? 2000 1345 Y ? Y ?
162 8 ? ? 1900 Y Y Y N
164 7 A ? ? 635 Y ? Y ?
229 6 A ? ? 1900 Y Y Y ?
257 7 ? ? 1350 Y Y Y Y
297 7 ? ? 600 Y Y Y ?

-John

I have been maintaining a spreadsheet as well, we can collaborate later. Print the sheet as a PDF and then post via picasa. Kind of a pain. My intention is a stastitical analysis of failures only. Bascially a weibull plot. The 8 seems to be off set to higher hours, but that is not significant as there are failures.

[Barry]

RV6A SN24431 First flew 1999.
O360 C/S 1060 Hours
No Aeros, Mainly flying off paved runways.
No Cracks. (praise the Lord)

Barry
RV6A F-PRVM

[zilik]

RV-6A SN22993
First Flight 2.8.2000
O-360-A1A
Hartzell C/S
1700 hours
Limited Aero, Paved Runways, Some Grass, Some Gravel
No Notches
No Cracks

[pmshep]

RV-7A. 340hrs 0-360 C/S mild acro no grass notches and a crack!:mad:

[mlgpilot]

Just checked my -7 and did not find any cracks. I even brought in another A&P, IA to really confirm my findings, all clear. My parts were notched. Aircraft info: S/N 71520, 220 hours T.T., O-360 engine and C.S. prop. Acro, loops and rolls only.
mlgpilot

[DarylT]

RV-7A
2004 vintage tail kit
Flying since August 2012
132 hours
185 hp IO-360-B1AD2
Hartzell cs prop
99% pavement
No cracks... yet
:eek:

[Neal@F14]

RV-7A. 340hrs 0-360 C/S mild acro no grass notches and a crack!:mad:

Metal CS prop (e.g. Hartzell BA) or composite CS prop (e.g. Whirlwind, Hoffman, MT, etc)?

[Bob Redman]

For the record:

RV-7, tip-up, #72450, Tail kit purchased Aug 2005, completed Dec 2005.
Aerosport IO-360M1, ECI comp, E/Pmag combo, 8.5:1.
Hartzell BA, balanced.
Basic weight 1085lb complete & painted, CofG 78.24 inches empty.
Plans built including notches, no mods except for Screaming Eagle tail wheel.
Total flight time 112 hours, including 2 hours of mild aeros (<0 to <+4G), 6 hours formation display (<0 to <+4G), and initial check to -3 and +6G, no inverted fuel or oil, first flight Aug 2011.
50/50 sealed/grass.
99 flights, 260 landings.

No cracks detected yet on either the forward or aft HS spars.

I intend to inspect regularly, wait for the factory options to evolve, monitor developments.

Thanks for the reasoned contributions, particularly from Scott. Thanks too to the people developing the record.

Regards

[Bikeman55]

[/QUOTE]Nothing for nothing - I'm sure we have some Bo owners/previous owners - I believe Bonanzas had a similar recurring inspection on the tail?[/QUOTE]

As a former Bo owner, I can weigh in on this a bit. Beechcrafts were hit with several AD's, one being inspection of the spar carrythrough structure for the wing. Some high time, hard use airplanes were developing cracks in that area. The fix was horrendously expensive, the number of affected airplanes was very small. It pretty much became a non issue, with inspection required at the annual. Always sweated it a bit, but never had a problem. It never did seem to effect the resale values.

The V-tail had it's own issues, the fix for the leading edge of the ruddervators was simple and effective. But they did definitely take a hit on resale that they haven't recovered from to this day. Straight tail Bo's just command a premium.

[cajunwings]

11 yr old RV 6A
520 hrs TT
180 HP IO-360
Hartzell C/S prop (not BA)
Not much grass or acro
Fairly sharp corners, no notches
Used lots of light and magnification

No Cracks

Don B
RV 9 Rebuild in Progress

[Capflyer]

Sorry if this was answered already, I probably missed it going through over 300 posts. Any thoughts on why the RV4 was not included? It has the same HS as the RV6. Wondering if it is simply because no cracks have been found on a -4 to date or another reason. I plan on inspecting mine regardless, it certainly can't hurt to look and only takes a few minutes. Besides I need to do the other SB anyway.

[mrblob]

2009 RV-7
380 Hours TT
360 hours with a H-6 Subaru and Sensenich 3 blade carbon
20 hours with IO-370 and aluminum Hartzell BA
Always operated on pavement
light acro
50/50 towbar / no towbar
Notches

I'm going with no cracks, but saw a line in the primer that made me nervous. Cleaned it up and I can't see anything, but I'm planning to use some dye penetrant to verify.

[RV8iator]

Has anyone found cracks on any RVs equipped with wood or composite fixed pitch props... or composite bladed CS props?

Going thru the reports posted thus far, unless I've missed something, it seems like only those with metal props (both FP and CS) are finding cracks.

My 8 has never had a metal prop. Wood the first 600 hours and composite the next 1300. Only a small crack on the top right side, but a crack is a crack.

[tracy]

I can't figure out why they want the flanges trimmed in step 10. Any thoughts?

[rgmwa]

I can't figure out why they want the flanges trimmed in step 10. Any thoughts?

I'd say it's to avoid the sudden transition in section stiffness that occurs when the ends of the channel flanges are squared off. Trimming the flanges will provide a more gradual change in the stiffness of the channel over the length of the taper.

[BillL]

It is difficult to capture in a post that will be read, but still say something useful, but here goes.

Of the 14 (yes there are more) cracks reported here with hours, they plot in a nice straight line on a Weibull plot, a statistical probability of failure plot.

Comparing each report hours to that expected for the fleet, this is about 1% of each years first flights beginning at 560 hours. There are some gaps, but that is pretty close. The only TT group that is odd is around 13-1400 hrs for the RV8, there seem to be 3 cracks reported in that hour group.

If half of all cracks have been reported here, then the crack occurrence rate is 2% of an hours group. Each hour group is 100-120 hrs. There are no failure reports above 2000hrs and no failures under 530 hrs. (update :340 hrs )The crack generation statistics may have as much to do with gust occurrence as prop or other hardware combination. If there were some strong influence of prop etc then the plotted data would not be a straight line. It was. The slope was 2.8 which is typical of a fatigue failure.

So, overall, if you have more than 560 hours you have a 2% (roughly) chance of finding a crack today. That is the same next year too, and the year after that. But the probability that you will find a crack eventually (3000hrs) is higher. This certainly supports the yearly inspection.

All in all my opinion is that this is, as Paul so clearly put it, not an emergency, and there should be no frustration or anxiety over this issue. Anyone who has built a plane has gone through much more in the process.

Hopefully this was helpful.

PS with the addition of the 340 hr report, there is a barely perceptible shift in the curve, along the thickness of the pencil line. Not enough to rep lot of change conclusions.

[Geeman]

No cracks.
RV-6
400 hours
50% grass
0-360
Metal Prop
Light acro
Finished in 2000
Relief notches and smoothed very well. I did not build the plane. Planning on routine inspection and leaving as is for now.

[jroser]

Hi Bill,
Thanks for tracking these occurrences. There is one person with 3900 hrs on his 6A with no cracks. Member's name is Rosie. Not sure how this affects your outcomes.

John

[scard]

Hi Bill,
Thanks for tracking these occurrences. There is one person with 3900 hrs on his 6 with no cracks. Member's name is Rosie. Not sure how this affects your outcomes.

John

Chuckle...


Other words here

[gazznsw]

RV6A VH-YOY
O-360 A1A
Hartzell C/S (Metal)
320 Hrs
Purchased last November
Mainly pavement, Very little acro
No cracks, with relief notches

[scsmith]

..... There are no reports above 2000hrs and no failures under 530 hrs. .....


Bill,

PMSHEP reported cracks at 340 hrs. see post #349

[Rob Kennedy]

Hello from South Africa RVAitors,

Checked my 7A yesterday and I have to say - really not a difficult exercise (on both SBs) Took about an hour all together.


No cracks.
RV-7A Reg ZU-ORV
499 hours
5% grass and gravel
Mattituck I0-360
MT 3 Blade Prop
Light acro, lot's of air-racing and formation.
Finished in 2008
Relief notches and smoothed very well. I did not build the plane. Planning on routine inspection and leaving as is for now.
__________________

[drycreekrv]

RV-6
Built before pre-punched kits were available
Approx 1600 hrs TT
Hvy to Modest Acro for 19 yrs
50% Pavement 50% Grass
Wood Warkne Prop
No Notches
No Cracks

[BillL]

Hi Bill,
Thanks for tracking these occurrences. There is one person with 3900 hrs on his 6 with no cracks. Member's name is Rosie. Not sure how this affects your outcomes.

John

All non failures had no bearing on the plot. We know what Mike Seager has over 4000 hrs on his 7 and we don't have data on the cracks found by Vans on the original articles either. Those were considered, but none of these single events will move the curve much and absolutely would not change the slope. With a little variance due to confidence band (75% probability that the plot is correct), we could easily have planes out to even 9000 hours without a failure. They, according to this plot, would be entirely possible, but obviously, rare.

Due to unknowns, only the slope and shape of the curve is close to firm.

As a practical point, none of this really means anything for decision making as an owner/builder, it is just a perspective that supports the SB. The SB addresses actions based on the hard known facts and is the only document that counts.

[Brantel]

Inspection party....

RV7 2010 somewhere around 300hrs
~1st 250hrs with a Metal FP Sensenich, ~50 or so with a Metal BAF Hartzell
O-360 Carbed
Very light acro
HS started life as a RV6 and has no notches
No grass time
No cracks


RV7 2007 630hrs
Metal BAF Hartzell
O-360 Carbed
Very light acro
Based on grass
Has notches
Cracks


RV6A 2008 700hrs
Metal FP Sensenich
O-360 FI
Very light acro
Little to no grass time
No notches
No cracks

[Walt]

According to Ken Scott the repair is no big deal (at least he didn't say "10 minutes")

Quote: Ken Scott of Van's told AVweb on Wednesday that repairs, if needed, should take a few hours at most.

Sorry but being in the repair business statements like this really aggravate the **** out of me.

I'd be more than willing to fly my airplane to the Van's factory if they will do the repair for "a few" hours labor!

[Snowflake]

I'd say it's to avoid the sudden transition in section stiffness that occurs when the ends of the channel flanges are squared off. Trimming the flanges will provide a more gradual change in the stiffness of the channel over the length of the taper.
Hmmm... But then you add a deep notch right where it ends? That alone is a stress concentration. I still don't understand why you would want the deep notches when you could just round the corner instead...

[Steve N.]

2002 RV-7 QB
First Flight JAN 2005
Aerosport I0360M1B
Hartzell C/S blended airfoil
716 hours
first 3 years on hard surface, last 5 years living on grass
mild aerobatics
Notches
No Cracks

[David-aviator]

It is difficult to capture in a post that will be read, but still say something useful, but here goes.

Of the 14 (yes there are more) cracks reported here with hours, they plot in a nice straight line on a Weibull plot, a statistical probability of failure plot.

Comparing each report hours to that expected for the fleet, this is about 1% of each years first flights beginning at 560 hours. There are some gaps, but that is pretty close. The only TT group that is odd is around 13-1400 hrs for the RV8, there seem to be 3 cracks reported in that hour group.

If half of all cracks have been reported here, then the crack occurrence rate is 2% of an hours group. Each hour group is 100-120 hrs. There are no failure reports above 2000hrs and no failures under 530 hrs. (update :340 hrs )The crack generation statistics may have as much to do with gust occurrence as prop or other hardware combination. If there were some strong influence of prop etc then the plotted data would not be a straight line. It was. The slope was 2.8 which is typical of a fatigue failure.

So, overall, if you have more than 560 hours you have a 2% (roughly) chance of finding a crack today. That is the same next year too, and the year after that. But the probability that you will find a crack eventually (3000hrs) is higher. This certainly supports the yearly inspection.

All in all my opinion is that this is, as Paul so clearly put it, not an emergency, and there should be no frustration or anxiety over this issue. Anyone who has built a plane has gone through much more in the process.

Hopefully this was helpful.

PS with the addition of the 340 hr report, there is a barely perceptible shift in the curve, along the thickness of the pencil line. Not enough to rep lot of change conclusions.

Thanks for statistical analysis Bill. It helps keep things in perspective.

While the SB is long and at first frightening, it is easy to live with. Inspect for cracks (which should be done in accordance with condition inspection anyhow) if all is ok, go fly for another year. The entire aircraft inspection process is no different. If something is in need of repair, fix it.

There is nothing new here - the SB is getting everyone focused on a potential problem and telling us how to deal with. That's good! That's how things should be in the aviation world.

[boomer]

I think it is important to remember that a sample size of 14 (or 140) is very small and any statistical data derived has a very low level of confidence. That's why telephone polls almost always have over 1000 respondents.

-John

It is difficult to capture in a post that will be read, but still say something useful, but here goes.

Of the 14 (yes there are more) cracks reported here with hours, they plot in a nice straight line on a Weibull plot, a statistical probability of failure plot.

[pgroell]

RV-7A
100h
O-360 FI
Metal FP Sensenich
99% paved runways
No acro
Notches
No cracks

I used a dental camera to get good light and good pictures.
(Search "Dental Camera on VAF and E-bay to get some info)

[colinr]

RV6
GDFUN
No Cracks found
Tailplane built around 1996. No Notches
O-320 (160 Hp)
Wooden Prop
All Operations of Grass
No Aeros
Total Hrs 110
Will continue to do annual inspections
Elevator also checked No problem

[Bavafa]

Thanks for statistical analysis Bill. It helps keep things in perspective.

While the SB is long and at first frightening, it is easy to live with. Inspect for cracks (which should be done in accordance with condition inspection anyhow) if all is ok, go fly for another year. The entire aircraft inspection process is no different. If something is in need of repair, fix it.


Considering the inspection takes only about 10-15 min, an annual inspection or every oil change should not be all that hard.

[walkman]

Are folks without cracks and without notches adding the notches?

It seems to me that, especially some of the higher time airframes, that it would be better to leave well enough alone and just inspect regularly.

Perhaps I'm falling victim to the Texas Sharpshooter fallacy, but it seems to me there is a strong correlation between the existence of notches and the incidence of cracks. By that I mean, the incidence of reported cracks appears to be lower on unnotched aircraft.

[pa38112]

I'm not adding them... unless some day I have to do the upgrade.

[Baby Bear]

Check my 8 this morning, very closely, as I have almost 1900 hrs on the old bird, and she has had a good work out now and then.

All is well. Would be interested in finding out some information on those that have found a crack, TT, aerobatics, bush flying, or different circumstances that they think may have influenced the "crack".

Baby Bear

[Mike S]

Thomas, welcome aboard the good ship VAF:D

[Louise Hose]

Quote: Ken Scott of Van's told AVweb on Wednesday that repairs, if needed, should take a few hours at most.

Sorry but being in the repair business statements like this really aggravate the **** out of me.

I understand your point but the word "few" really only means more than two, and I hope pilots are smart enough to realize such is the case. What Ken was really saying is that it will take more than "a couple" (two) hours to perform the fix. There is an implication that it will take significantly less time than building an entire RV. Nothing more.

100 hours is a "few" if your reference point is building the entire airplane (including smelting the ore, manufacturing the parts, transportation, etc.). 1000 might be considered a "few" in the context of building the entire International Space Station. ;)

[Rodoc]

I inspected mine today and was pleasantly surprised that I have no evidence of cracks. I would have thought that I was a prime candidate based on others who have cracks. I have:

RV-6 kit from 1996
No stress relief cutouts
800 hrs including frequent loops, one or two 5g sustained turns, rare snap rolls and spins, and racing at Reno in excess of Vne.

So why don't I have cracks? I have 2 thoughts on that matter.

As I took the fairing off today I noticed all my unused nutplate holes in the skin edge. My fairing fit so poorly that I made my own (partly because my prop spins opposite direction any my rudder incidence is in the opposite direction). anyway, the home make one fits well enough to be held on with only a few screws. There are no attachments in the skin of the h-stab. I wonder if the forces on the fairing could be playing a role in these cracks.

The other main difference for me is my engine and the more frequent but weaker pulses from the engine and prop. Someone already mentioned that this may be a factor.

[RONSIM]

RV-6A, 1993 vintage, 900hrs TT, IO360 CS ---- notched, no cracks

[rgmwa]

Hmmm... But then you add a deep notch right where it ends? That alone is a stress concentration. I still don't understand why you would want the deep notches when you could just round the corner instead...

There are notches and there are notches. A sharp notch can act as a localised stress riser, and a well formed notch will tend to reduce stress concentration. But as has been pointed out in another post, the top and bottom notches in this particular case also reduce the overall depth of the plate, resulting in higher stresses simply due to the smaller cross section (as opposed to a localised stress concentration).

Perhaps the notches in this particular case are something of a double-edged sword - reducing stress concentration, but at the cost of raising the overall stress levels in the plate. Maybe that's why there appears to be no strong correlation between the presence of notches and the presence or absence of cracks. In any case, as was alluded to in post 277, it's good practice to avoid sudden changes in stiffness, which may be the reason that Vans have asked for the flanges to be tapered.

[painless]

RV6A
1997 vintage empenage kit
flying since 2006
194.5 hrs
O320 E2D 150hp
Catto three blade
rolls only, not very frequently
no grass
no notches
no cracks in HS spar web or elevator rod end platenuts


Examined with dental loupes and LED illumination

[C-J]

I went out to inspect "Redhawk" RV 7A (Serial 73077) today. The plane has 340 hours, light acro, mostly paved strips. IO 360 M1B, fixed metal Sensenich prop. Bounced in really hard trying to jump over debris on the runway at KIGX and bounced to 4-6 G in turbulence going over the mountains. It is a quick build, but I built the tail from Vans match hole tail kit in the summer of 2007. My plans required the relief notch 5/16" over from the where the spar web flanges are bent. We looked very carefully and found no indications of cracks at this point. The notch was very smooth, I like to buff the edges in places like this, not saying one won't develop. Lastly, I don't know if it make any difference, but my tail fairing is very modified, wraps around the stab leading edge and attaches in the rear, so I don't have the nut plates at that intersection, but a rivet instead. My flanges seem to lay very flat in that area vs some of the pictures that I have seen, not sure what the difference may be. I hope the helps the data keeper.

I'm building an RV 14 now, and the double spars is really stout on this ship. We plan to watch the stab frequently since it is only a few screws to remove the fairing on the 7 and use dye penetrant each annual.

I think my would preference would be to build a new stabilizer for the RV 7 if Vans were to offer an enhanced or improved version at a reasonable price vs the retrofit. I've been told my building skills are pretty good and I think I could do a good job on SB 14-01-31, but my gut would feel better with a new stab. CJ

[T6pilot]

RV 6
1998
978 TT
IO-360
CS
No notches
No cracks
Grass strip two years

[G5Driver]

RV-8 (no notches....no cracks)
0-360, CS Prop, 582 hrs., Paved runways, Lots of acro.

[SMO]

.........Maybe that's why there appears to be no strong correlation between the presence of notches and the presence or absence of cracks.

Been following this thread and I would say there is a statistically significant correlation between the presence of notches and the presence of cracks - over 80% of the cracked spars reported here have notches - only a couple without notches have reported cracks. While I have not tabulated it, the distribution of notched spars vs non-notched appears relatively even.

[rgmwa]

Been following this thread and I would say there is a statistically significant correlation between the presence of notches and the presence of cracks - over 80% of the cracked spars reported here have notches - only a couple without notches have reported cracks. While I have not tabulated it, the distribution of notched spars vs non-notched appears relatively even.

You may be right. I guess time will tell.

[Robert Babler]

2011 RV7 N797RB
210 hours TT
AeroSport IO-375
WW 200RV
Light Acro
Some grass, mainly pavement
Tow bar, tow strap
Notched
No cracks

VAF 2014 Dues Paid

[jimgreen]

My buddy and I inspected today:

7A with O360 180hp, Hartzell metal prop.
410 hrs
Lots of acro
No notches
No cracks!

7 with IO360 180 hp, WW200RV composite prop.
125 hrs
Some light acro
Notched
No cracks!

[Captain Avgas]

On a lighter note, I'm noting an amusing trend to this thread.

Those with composite props are tipping that the cracks are caused by metal props.

Those with nose wheels are suggesting that the problem may be more widespread among tail draggers.

Those with no notches are predicting that notches are the problem.

Those with notches are tipping that notches will be superior as long as they're meticulously deburred (I happen to fall into this camp).

I'm therefore coming to the suspicion that many of the suggestions on this thread are less science and more wishful thinking. :D

[Bavafa]

On a lighter note, I'm noting an amusing trend to this thread.

Those with composite props are tipping that the cracks are caused by metal props.

Those with nose wheels are suggesting that the problem may be more widespread among tail draggers.

Those with no notches are predicting that notches are the problem.

Those with notches are tipping that notches will be superior as long as they're meticulously deburred (I happen to fall into this camp).

I'm therefore coming to the suspicion that many of the suggestions on this thread are less science and more wishful thinking. :D

I did not find any cracks in my HS and believe my brand of EIFS has much to do with that.

[Low Pass]

On a lighter note, I'm noting an amusing trend to this thread.

Those with composite props are tipping that the cracks are caused by metal props.

Those with nose wheels are suggesting that the problem may be more widespread among tail draggers.

Those with no notches are predicting that notches are the problem.

Those with notches are tipping that notches will be superior as long as they're meticulously deburred (I happen to fall into this camp).

I'm therefore coming to the suspicion that many of the suggestions on this thread are less science and more wishful thinking. :D
But notches really are the problem! (Deburred or not.) ;)

[walkman]

1999 rv-6
830 ttaf
O360 counterwghted crank
Hartzell c/s prop
Regular mild Afro
Occasional grass
Notches
GRT efis
No cracks either sb

Whew

[scrollF4]

I have a tip-up. I have no cracks. Therefore, sliders = cracks. Whew!

Ps: I also have 0 hours on the airframe, with another 500+ hours of build ahead of me. But it's a good thing I have a tipper!

[lorne green]

I did not find any cracks in my HS and believe my brand of EIFS has much to do with that.

Now that's funny!:p


I don't have any cracks on my HS, but I'm not flying yet either.:D

[Captain Avgas]

On a more serious note.

This thread will be providing enormously important feedback for Vans. I'm absolutely sure they will be religiously monitoring it on a daily basis for information resulting from the individual aircraft inspections for cracks. People are reporting back to this thread on VansAirforce....they're not reporting back to Vans.

In other words, up until now, Vans has probably had very little hard information on the actual extent or nature of the cracking. They knew it was a problem with serious implications but they just didn't know how widespread the cracking was. Their sample would have been too small. Now they're finding out (and so are we).

We can be of major assistance here to Vans. And the more we assist them, the more knowledge they will have, and thus the better their solution to the problem (the more they can assist us).

How can we assist them.

Firstly, keep reporting results of inspections....everyone should report here. Even if you don't normally post on VansAirforce, make the effort. You're an important part of this important survey.

Secondly, be careful with your inspection. As reported these cracks can be very difficult to detect with the naked eye. A false report is worse than no report.

Thirdly, report both good and bad results. My guess is that those with cracks may be more reluctant to report for one reason or another than those with no cracks. That may skew the data and hide the extent of the problem.

Fourthly (and this may be the most important), if you have a crack then send photos of the cracked area. This will be most important to Vans. As they say a picture is worth a thousand words.

Fifthly, provide maximum aircraft data as previously requested (model, year, hours, notched or not, aeros, runway, prop type, etc)

[N363RV]

I'm happy to have a little skin in this game. Just inspected mine. No cracks. 0hrs. Lots of aerobatics being moved from one space to another in the shop! I'm looking forward to getting the parts so I can utilize my expertly honed rivet removal skills :). This is going to be an easy couple hour project for those of us that have yet to install the HS. I do feel a bit sorry for those that didn't build their airplanes or otherwise have acquired the skills.

On a normal day I would say "you crack me up!", but it just doesn't seem appropriate right now. But you did bring a smile to my face. :D

[rvdave]

Haven't heard anything mentioned about small vert stab & rudder for the six's that kept originals as does the rv4 having small vs & rudder. Any of those showing cracks? Just checked mine today-short original vs & rudder--no cracks in HS . Don't know if that is even a factor?

Dave Ford
2004 RV6 FADEC

[Snowflake]

Possible new info:

I initially thought I was crack free, having pored over the photos I took of the four corners in great detail. However, I happened to open them up again and noticed something I had missed on first review... The photo below is taken with the camera in the space behind the front spar, and the lens oriented roughly towards the passenger wingtip. So you're looking at the top right stress point in the SB.

Look at the rib at the right of the photo though, specifically the bend in the flange that joins it to the back of the front spar. Right beside that top rivet, is a crack that extends down at least the width of the rivet head. It's very faint to see, but the rivet head is just above the center of the photo, the crack just to the right of it.

I wonder if this is related to the failure in the SB, and if people should check for this as well... Maybe my shear web didn't crack because this part did?

https://lh5.googleusercontent.com/-MfSTare6ovY/UvMJAWTcSmI/AAAAAAAAGGA/sK4i5D922gw/s1024/IMG_20140202_160352.jpg

In any case, as the crack in question would be fixed if I did the SB, I'll be ordering the kit.

If the photo doesn't embed properly for some reason, here's the album with all four corner photos (yes, I know it's dirty... the annual is coming and it's bl**dy cold in the hangar right now).
https://picasaweb.google.com/111320027198216670014/RVTailPhotos?authuser=0&authkey=Gv1sRgCIuN5Ofwz8yrUQ&feat=directlink

[Captain Avgas]

Possible new info:

Look at the rib at the right of the photo though, specifically the bend in the flange that joins it to the back of the front spar. Right beside that top rivet, is a crack that extends down at least the width of the rivet head. It's very faint to see, but the rivet head is just above the center of the photo, the crack just to the right of it.

https://lh5.googleusercontent.com/-MfSTare6ovY/UvMJAWTcSmI/AAAAAAAAGGA/sK4i5D922gw/s1024/IMG_20140202_160352.jpg


Rob, fascinating photo. And very important. Good on you. You are to be commended for observing this and posting an image.

People who have been inspecting their aircraft and reporting no cracks might like to take a second look if all they were inspecting in the first instance was the "notched" area (ie. they were too focused).

As per my post #400, this shows the reason why people with cracks need to be posting a photograph. This type of visual information could very easily result in Vans having a second think about this issue.

It certainly looks like a crack in the photo. Are you certain that it is.

[skylor]

1999 rv-6
830 ttaf
O360 counterwghted crank
Hartzell c/s prop
Regular mild Afro
Occasional grass
Notches
GRT efis
No cracks either sb

Whew

I'm still trying to figure what hair style has to do with cracks!

Skylor

[Snowflake]

It certainly looks like a crack in the photo. Are you certain that it is.
I have not gone back with tools and confirmed with my hands on it. But I have three photos all from slightly different angles (I was trying to get the SB location in focus) that *together* lead me to believe it's a crack. That's just the best photo with the "crack" in sharpest focus.

I won't be able to confirm 100% until the weekend when I get to the airport again.

[Bob Ellis]

RV-8
May 2012
130 hrs
no notch (not in plans)
Approx 75% Hard 25% Grass
Mild aeros and Formation
Catto 3 Blade composite FP
ASP IO-360 Dual P-Mags
No cracks

[John Collier]

Some have said they figure building a new stab would be easier.
I think it would be probably double the work time (assuming an already removed one getting the mod installed). One thing to consider before doing this... The bolt connections that attach the stab to the fuselage are just as important as any of the rivets that need to be removed are. Do you know for certain that when you drilled those holes, they were drilled exactly perpendicular to the parts involved. Are you confident, that you can accurately match drill, from below (in a very limited work space), to have a good close clearance fit between the fuselage and the new stabilizer?
I am not saying it can't be done. I have done it, and others have also.

If I find cracks...I'd prefer to build another horizontal stab...my workmanship was at its lowest on the tail. So...has anyone installed a new stab on an aircraft? The above quote about match drilling it to the fuselage has me questioning whether I should go this route. Any experience is greatly appreciated. PM is fine as I don't want to derail this thread. If I go this route...or get any good info...I'll start another thread.

Thanks!

[N316CZ]

450 hours
RV6
180
CS
No cracking:)

[DanH]

Note the inspection instruction: 'Clean the area and remove any paint, overspray or primer that could hide a crack. Cracks may be very small and hard to detect.'

Good question for the group: This is a small area in an awkward location tucked into a nest of separate parts. All factors considered, what is the best way to strip the paint for a really close inspection?

[Walt]

Good question for the group: This is a small area in an awkward location tucked into a nest of separate parts. All factors considered, what is the best way to strip the paint for a really close inspection?

Using some type of chemical stripper would be required as mechanical stripping will tend to fill and hide a crack if present.

[revenson]

7A
360 hrs
no notch
All paved runways
No aerobatics so far
WW200 prop
IO-360 Dual P-Mags

No cracks.

[Bikeman55]

Good question for the group: This is a small area in an awkward location tucked into a nest of separate parts. All factors considered, what is the best way to strip the paint for a really close inspection?

So what strips Jet Glo? And how do you get the residue out of the nooks and crannies? Would not getting it out lead to corrosion issues?

[David-aviator]

Possible new info:

I initially thought I was crack free, having pored over the photos I took of the four corners in great detail. However, I happened to open them up again and noticed something I had missed on first review... The photo below is taken with the camera in the space behind the front spar, and the lens oriented roughly towards the passenger wingtip. So you're looking at the top right stress point in the SB.

Look at the rib at the right of the photo though, specifically the bend in the flange that joins it to the back of the front spar. Right beside that top rivet, is a crack that extends down at least the width of the rivet head. It's very faint to see, but the rivet head is just above the center of the photo, the crack just to the right of it.

I wonder if this is related to the failure in the SB, and if people should check for this as well... Maybe my shear web didn't crack because this part did?

In any case, as the crack in question would be fixed if I did the SB, I'll be ordering the kit.

Rob,

It appears the shear web is not cracked, just the rib flange. Seems like that could be repaired with a doubler along the rib flange down to the second or third rivet. The SB does not address a cracked rib flange.

The front spar bend of 6? is a bucket of worms. Cracks are occurring in the vertical sheer web at or near the bend perhaps because it is not assembled perfectly or the area is under stress because the parts do not match perfectly. The notch may facilitate cracking since there is less material to carry the load through the bend.

How come late RV-8 HS-702's do not have the notch whereas early RV-7's have the notch where cracks are occurring, the data indicating more frequently than without the notch? And now the SB advises to make the notch .25" or greater if it is not present?! This seems inconsistent with the data concerning the occurrence of the problem. The SB doubler probably will prevent cracking of the vertical sheer web though the bend but why make the big notch? It did not prevent cracking from the git-go.

[JonJay]

If I find cracks...I'd prefer to build another horizontal stab...my workmanship was at its lowest on the tail. So...has anyone installed a new stab on an aircraft? The above quote about match drilling it to the fuselage has me questioning whether I should go this route. Any experience is greatly appreciated. PM is fine as I don't want to derail this thread. If I go this route...or get any good info...I'll start another thread.

Thanks!

Match drilling aluminum through aluminum with a hole already drilled to finished size is always going to be a challenge even when you have good access to the work piece. Scott's concern is very legitimate in that you will have much less than perfect access added to a tricky procedure.

While I have not replaced a HS, when I encounter this situation, I fabricate a drill bushing. For one time or very limited use, that bushing can be made from almost any material, however, steel is best. I make my own on the lathe but there are commercially available drill bushings in many OD and ID sizes.

With the bushing to protect the hole, you can drill the pilot hole accurately. Once the pilot hole has been drilled it acts like a guide.

You will need a 90 deg. drill. Without a bushing getting the 90 deg drill straight in a limited access area will be tough. The bushing insures you drill a straight hole.

[Walt]

The question of log entries came up in another tread but I thought it would be useful for folks that may not see it there.

When you notate in the logbook you should state how you complied with the SB.
Example:

C/W SB XXX dated xxxx by inspection, no cracks noted at this time. Re-inspect due at next annual inspection.
or:
C/W SB XXX dated xxxx by installation of doublers HS-XXXX and Rib Flange angles. This repair is considered terminating action.

[Walt]

Match drilling aluminum through aluminum with a hole already drilled to finished size is always going to be a challenge even when you have good access to the work piece. Scott's concern is very legitimate in that you will have much less than perfect access added to a tricky procedure.

While I have not replaced a HS, when I encounter this situation, I fabricate a drill bushing. For one time or very limited use, that bushing can be made from almost any material, however, steel is best. I make my own on the lathe but there are commercially available drill bushings in many OD and ID sizes.

With the bushing to protect the hole, you can drill the pilot hole accurately. Once the pilot hole has been drilled it acts like a guide.

You will need a 90 deg. drill. Without a bushing getting the 90 deg drill straight in a limited access area will be tough. The bushing insures you drill a straight hole.

I agree with the above, it will be very difficult to do this accurately with the limited access and back drilling with a 90 deg drill. This is the main reason I will probably do the repair vs building a new HS.

[selhardt]

Inspected mine yesterday.

Most of the time spent removing paint - had gotten clear coat in this area - really just the top and it had to be sanded slightly before I could get any traction with a Q tip and PPG reducer. Didn't sand to metal of course - just enough to get going with the Q tip.

Finally got everything to shiny aluminum and touched it up with NAPA 7220 and a Q tip when done.

RV8, 82960
IO360,
CS Wirlwind RV200
90 hrs. total
Mostly Asphalt, but grass ops too
Acro
No Notches
No Cracks

[walkman]

I'm still trying to figure what hair style has to do with cracks!

Skylor

Apple speling autokerrect. Decided to leave it as is for the laffs

[Bavafa]

Inspected mine yesterday.

Most of the time spent removing paint - had gotten clear coat in this area - really just the top and it had to be sanded slightly before I could get any traction with a Q tip and PPG reducer. Didn't sand to metal of course - just enough to get going with the Q tip.

Would a dye penetrant work over this kind of paint and if so which kit works best?

All this conversation is creating enough doubt in me to go back and do the same.
I examined mine with a 2x magnifying visor (I could not get closer with stronger magnifying glass to be focused) and the pic that I took, could zoom it in for real close up. There is certainly no crack shown in the pic but I might go and remove the paint though that would not be an easy task with the clear coat and all.

[az_gila]

I agree with the above, it will be very difficult to do this accurately with the limited access and back drilling with a 90 deg drill. This is the main reason I will probably do the repair vs building a new HS.

If I had to do it, I think I would fabricate a stiff metal template that referenced the rear spar to the mounting holes on the main HS spar.

The template could be easily pilot drilled with the old HS off the plane, and then used to drill the new HS while it is inverted on the workbench.

IMHO trying to backdrill the forward spar mounting holes would be a recipe for disaster - just getting the drill and your hands inside the fuselage would be difficult.

[Lars]

Good question for the group: This is a small area in an awkward location tucked into a nest of separate parts. All factors considered, what is the best way to strip the paint for a really close inspection?

MEK and a whole lot of cotton swabs in my case.

[wera710]

2006 RV-8 (Slow Build)
488 TT
O-360
Hartzell CS Prop
Pavement and Grass
Light Acro
Tons of formation
No Notches
No Cracks

[ernestn]

RV-6
Kit started in 1991 finished in 1997
1035 hrs
O360
Warnke & then Catto prop
light acro in the last 100 hrs (4.7g max)
mostly pavement but occasional grass (<5%)
notches
No cracks

[JonJay]

Match drilling aluminum through aluminum with a hole already drilled to finished size is always going to be a challenge even when you have good access to the work piece. Scott's concern is very legitimate in that you will have much less than perfect access added to a tricky procedure.

While I have not replaced a HS, when I encounter this situation, I fabricate a drill bushing. For one time or very limited use, that bushing can be made from almost any material, however, steel is best. I make my own on the lathe but there are commercially available drill bushings in many OD and ID sizes.

With the bushing to protect the hole, you can drill the pilot hole accurately. Once the pilot hole has been drilled it acts like a guide.

You will need a 90 deg. drill. Without a bushing getting the 90 deg drill straight in a limited access area will be tough. The bushing insures you drill a straight hole.

An excellent point was brought up to me off line. We are assuming the original holes where drilled square. This is a big assumption.

[APACHE 56]

2012 RV-8
179.1 HRS TT
IO-390
MT CS Prop
Pavement
Light Acro
Radius (but not nearly as dramatic as shown in SB)
No Cracks

[johnfurey]

Just a dab of paint stripper on each location, wait 15 minutes and wipe clean. Cut right thru clear coat-paint-primer. Stripper needs to be about 70 degrees to work well. Fumes are bad.

[bjdecker]

2007 RV-7
450.4 HRS TT
IO-360-A1B6, 200HP, Dual LS ignition
Hartzell C/S Prop -- Balanced
99.9% Pavement
Light Acro
Radius - per plans
Two Cracks, upper corners - radius to rivet hole

http://i1060.photobucket.com/albums/t459/N374BD/9FF186A4-B780-42C9-A0B7-DF8B3003A676_zpsxzasxbrx.jpg

http://i1060.photobucket.com/albums/t459/N374BD/58BC474B-CE3D-4735-9DFF-CD2718BAE3B0_zps4jcjbxlv.jpg

Crack happened sometime between July 2008 and now -- who knows...
SB Kit ordered; should be a nice weekend project :/

[GLPalinkas]

MEK and a whole lot of cotton swabs in my case.

+1 on the MEK and cotton Q-Tips. Worked for me.

[Mike S]

Just a dab of paint stripper on each location, wait 15 minutes and wipe clean. ---

---Fumes are bad.

Please read the instructions on any stripper---------some of them do not play well with aluminum.

[Gash]

RV-8
165 hrs TT
IO-375
Whirl Wind 200RV prop (balanced)
Paved runways
Light acro <4 Gs
No notches
No cracks

[jpallist]

Inspected my early model 6 (kit purchased in 1989, finished in 1999). 980 hrs; 0320, MT fixed pitch, light acro.... no cracks.

[KTM520guy]

Just a dab of paint stripper on each location, wait 15 minutes and wipe clean. Cut right thru clear coat-paint-primer. Stripper needs to be about 70 degrees to work well. Fumes are bad.

15 minutes? Ain't nobody got time for that. I'm thinking more like 1 minute. Got to use the good stuff.

[Nomadicram]

RV-7 Tipup
Serial #70-426
Completed 2005
O-360 CS
980 TT
Light Acro
Paved Runways primarily
No Notches
No Cracks

[Ironflight]

Got to use the good stuff.

Do we even dare ask what that might be?!:rolleyes:

[hudgin]

2008 RV 7
431.6 Hrs TT
IO-360-A3B6D converted to a IO-360-A1B6D converted to a single Bendix 1200 mag and a ElectroAir ignition.
Hartzell CS Semitar balanced cchecked OK by Walt
90% paved stripes
Light + G's acro (no spins)
Radius per plans
1 crack on the right side
Past Crack History: alternator heat shield 2 times, cyl 1 & 3 exhaust 3 times, tail pipe mount 6 times. All on the right side.

[hockeypilot]

No cracks
no notches
light acro
pavement
0360
Wood
Rv8

[RV7AZ]

No Cracks
2005 RV-7A
510 TT
No acro or heavy Gs
Only a few dirt landings, no grass
Notch
IO-360-B1B
Hartzell Blended Airfoil

[KTM520guy]

Do we even dare ask what that might be?!:rolleyes:
I'll give you your first taste for free. After that it will cost ya. Everybody always pays in the end. lol

[DanH]

I'll give you your first taste for free. After that it will cost ya. Everybody always pays in the end. lol

Paul, I think he is talking about the stuff the Carolina bunch brings to Triple Tree in fruit jars.

[Robski]

Good afternoon from the UK.

Just checked the RV6.
Built 1994. Not changed significantly since.
600 hours.
O-320.
Warnke wooden prop.
Operated of every kind of surface.
No aeros to speak of.
No notches.
No cracks.

[Charlie B]

RV-6A Quickbuild (1999 kit) Empennage built by factory.
Flying since mid-2007
160 HP 0-320 with electronic ignition
Whirlwind 151 Prop (3 blade, constant speed)
All hard surface ops
300 hours
LOTS of acro
No towbar, but no push on HS.
Notches
No cracks

[cjhukill]

RV8 with 500 hours. Plenty of acro and mountain turbulence. No unimproved fields, but lots of rough asphalt. No notches or cracks.
Chris Hukill

[az_gila]

Do we even dare ask what that might be?!:rolleyes:

This one works well, but if you get a drop in your skin, it burns...:eek:

http://www.aircraftspruce.com/catalog/cspages/ptipaintr.php

[KleensRV6]

1995 RV 6
1010 Hrs TT
IO-360-A1A converted to a single Slick mag and a ElectroAir ignition.
Hartzell CS
98% paved stripes
Very Light + G's acro (no spins)
1 crack on the left side

[LettersFromFlyoverCountry]

Just via anecdotal evidence, I'm intrigued by the number of no cracks/no notches conclusions. Do we have that broken down further yet?

[kiwipete]

Rv-7 2007
350 hours
Superior IO-360
Hartzell Blended Aerofoil
Notches well radiused
Lives on grass which can be quite bumpy
Occasional aero's +G normally no more than 4
spun a couple of times per year.
No cracks

However I have had engine mount cracks on the gear legs as per most of the UK fleet that operate off grass.

[Bavafa]

Just via anecdotal evidence, I'm intrigued by the number of no cracks/no notches conclusions. Do we have that broken down further yet?

The idea of ?notches? might be a bit subjective here. I have seen some of the pix posted here that they say notched and to my eye and based on the pix provided, it look hardly any notches there.

Here is one with a clear notch

http://farm3.staticflickr.com/2884/12287309054_690f4d983b.jpg (http://www.flickr.com/photos/61260420@N07/12287309054/)
HS3 (http://www.flickr.com/photos/61260420@N07/12287309054/) by bavafa1 (http://www.flickr.com/people/61260420@N07/), on Flickr

[Low Pass]

The idea of ?notches? might be a bit subjective here. I have seen some of the pix posted here that they say notched and to my eye and based on the pix provided, it look hardly any notches there.

Here is one with a clear notch

http://farm3.staticflickr.com/2884/12287309054_690f4d983b.jpg (http://www.flickr.com/photos/61260420@N07/12287309054/)
HS3 (http://www.flickr.com/photos/61260420@N07/12287309054/) by bavafa1 (http://www.flickr.com/people/61260420@N07/), on Flickr
Interesting about the position of this "notch". How would one see any potential cracking behind that rib flange? Tough dilemma.

[jbDC9]

Interesting about the position of this "notch". How would one see any potential cracking behind that rib flange? Tough dilemma.

That was my exact thought when I saw that pic; the rib flange covers where the crack is in most of the other crack pics.

BTW, love the new avatar pic...
"Well, I've been to one world fair, a picnic, and a rodeo, and that's the stupidest thing I ever heard come over a set of earphones. You sure you got today's codes?"

[glider4]

RV-8A N880AT inspected today for both SBs. Time to remove H/S+V/S fairing, inspect and re-install fairing was 1.4 hours. No cracking found in any of the locations specified by the two SBs.

My RV-8A has 10.3 hours airtime and has a IO-360 with a FPP. I fly off paved runways at S03 (Ashland, OR).

I do have a "new" never installed H/S and right elevator available. These were built 10 years ago but never used. No cracks in these! I acquired them at an estate sale back in mid-2004. Worksmanship on these is about a B- or so. Will sell for cost of materials if anyone out there needs a H/S or right elevator quick. $400 for the H/S and $200 for the right elevator. Local pick up in Ashland, OR area or can deliver up to 400 miles round trip for gas $s. These are way too expensive to ship!

Albert Thomas
303-241-0789

[Bavafa]

Interesting about the position of this "notch". How would one see any potential cracking behind that rib flange? Tough dilemma.

Very good point has been brought up. I have pictures of both side and only one side is being covered like this. I will make an attempt of trying to bend the rib flange and check for crack. I am also contemplating of doing the SB regardless for a piece of mind.

[Gonzo24]

I called Van's and spoke with Bruce on the Parts order line. Said I wanted to order all HS parts and SB kit except the rear spar components (I intend to re-use my rear spar in the new assembly as I have elected to rebuild the HS while it's in the shop). Was told that he could not take my order since, "The engineers were in a brain trust working it out". I inquired what that meant exactly. Was told that a fix is coming. Asked another question about leadtime...

I thought the SB kit was the fix. I'll wait a few weeks and see what shakes out. Very interesting.... Anyone else run into this?

[BillSchlatterer]

Interesting about the position of this "notch". How would one see any potential cracking behind that rib flange? Tough dilemma.

So maybe that is some of it. In this picture (as in my 7a) the notch is further outboard and appears to be more centered over the bend line which I think is on the edge of the flange. If the notch is more inboard of that, which many seem to be based on the relationship to the rib flange. It may be that the notch isn't working well in some cases because it is a half inch too far inboard.

Just saying that it seems to me like the notch should be centered on the bend line and many are inboard of that. I think you can see that in many pictures by looking at the location relative to the rib flange. I think this is the way it is supposed to be ..... slightly under the flange.

Of course many are flying fine with no notches at all.

Just thinking out loud ....

[Gonzo24]

My intention is not to rag on Van's. I think they are doing a good job with this SB business. Just curious if anyone else has been placed in the holding pattern trying to order parts? The hang up could have been an accident... it happens

[LifeofReiley]

My intention is not to rag on Van's. I think they are doing a good job with this SB business. Just curious if anyone else has been placed in the holding pattern trying to order parts? The hang up could have been an accident... it happens

I don't think anybody wants to rag on Van's, people are just shook up a little and are looking for answers.

[Sam Buchanan]

snip.... I know the heat is turned up a little at Van's ...snip.

snip dr

Personal vendettas will not be tolerated. We have much more important matters that need to be attended to. Please don't encourage us mods to push the button.....

[Tedtheflyer]

I inspected our RV-7A N569TC today. The stabilizer and elevator were inspected for cracks per both service bulletins. Our HS spar is relieved (notched) per plans. No cracks were found.
TTAF 360 Hr's
IO360 M1B
Hartzell Blended Airfoil CS Prop
Fly from paved fields only
No Acro
Tedtheflyer

[Tedtheflyer]

Sorry, our RV-7A first flight was 5-09

[Mike S]

No, it wasn't rude...Scott exercised great restraint to avoid being drawn into a childish shoving match.

Personal vendettas will not be tolerated. We have much more important matters that need to be attended to. Please don't encourage us mods to push the button.....

Right on Sam.

[lernez]

RV-6A, N207A
Built: 1993
4th owner
TT: 1490
Lyc 0-320 E2D
Sensenich FP prop
No acro
No grass field ops
No notches
No cracks r.e. both SB's

[JAVIER]

Van's SB's
RV-8 ECXJG
spain
Built: 2012
TT: 70
Lyc IO360M1B
Sensenich FP prop
acro <4gs
No notches
No cracks r.e. both SB's

[rstisser]

RV-6A
TT 988
Lyc 0360
Sensenich FP Metal Prop
Gentleman Acro
Notches
mostly paved
1 Crack top starboard front spar radiating from notch
1 Crack outboard elevator below jam nut

[NYTOM]

My intention is not to rag on Van's. I think they are doing a good job with this SB business. Just curious if anyone else has been placed in the holding pattern trying to order parts? The hang up could have been an accident... it happens

After reading everything I could on the SB I ordered one up online three days ago figuring it would be weeks with all the interest. :(
Really surprised to find a big shipping envelope in my mailbox today from Vans. :eek: Three days... Normally I can't get things I need ASAP that fast.:)

[jsharkey]

RV-6
TT ~120
YO360-A1A
Sensenich 72/85 metal
Grass strip
A few aileron rolls
Tend to push with tail
HS-602 Fwd Spar - small notches
No cracks

Jim Sharkey

[gerrychuck]

RV6A circa 2003
375 TT
0-360 A1A
Sensi FP prop
No acro or grass in past 75 hrs (aircraft bought flying at 300 hrs)
Small notches
No cracks


Needed hi res pics with a lot of magnification to reassure myself that the bottom starboard notch didn't have a crack. Probably should have cleaned overspray off better, but I'm confident I'm okay for this year. I would absolutely not trust the naked eye alone on this; I got so much more detail from the pics.

[n816kc]

2010 RV-6
326 hours TT
O-360, Sensenich metal
Light acro, minimal grass
Small notches

[ok3wire]

1993 RV-6
4th owner
700 TT
Lyc 0-360
Sensenich FP
light/moderate maneuvering/acro (<5G's) since i've owned it (80hrs)
no grass since i've owned it
no notches that i could discern
no cracks on either SB :)

[rvbuilder2002]

I posted earlier in the thread that I would link to the rivet removal procedure when it published. Since it has not yet, and some people are starting to do work on their stabilizers, I decided to to ahead and write up a description of the procedure(s) that I use.

If interested, you can find it in THIS THREAD (http://www.vansairforce.com/community/showpost.php?p=852120&postcount=17)

[bret]

I have successively removed the HS 404 and 405 ribs today:D the hardest part was drilling from the rear towards the front to remove the rivets that hold the 404 and 405 together. I used a 12 in 40 drill, flex with a rag holding the bit perpendicular to the flange 3/4 the way through, drilled the manufactured head slightly with a 30, took a sharp wood chisel to remove the head, took a 16 nail turned down to fit in the 40 hole, taped to the rivet gun on 20 psi, taped a nut on my tungsten bucking bar for the back stop dolly and pulled the trigger ever so slightly. Clean holes! I got the procedure idea from Walt's post but had to come up with an idea to do this single handed.

[n8433w]

RV-8
Built 2001
3rd owner
TMX 0-360
Hartzel Blended Airfoil
805 hours on airframe
Acro limited to <4g
1 crack on RH spar
No cracks on elevator
Planning on installing ALL reinforcements while it is disassembled

[jdiehl]

2012 RV-7A
105 hrs T.T.
Lyc o-360-A1A
Sensenich FP Metal 72/85
No Acro
No Grass
Notches
No cracks either S.B.

Often run @2200 rpm @about 130K in cruise.
Seldom run @2400+ rpm. (in cruise)

[ILikePike]

Pictures Bret?

[bret]

Pictures Bret?

well, kinda getto, but it worked.
http://i895.photobucket.com/albums/ac158/bret496/DSC04413_zps0af627a5.jpg

[bret]

So if you did the HS like me, the manifactured heads are facing rear, and HS 405 is installed so that it is dificult to drill, I had to bend the 12inch 40 drill while drilling to get a straight shot in the MH of the rivet. These are the tools I used. Kinda back yardish but it worked.

http://i895.photobucket.com/albums/ac158/bret496/DSC04414_zpsdc0b2845.jpg

[lostpilot28]

Quick question before my stats. Before I went out and complied with the SB, I thought it was only for the "top" left & right of the forward spar. I didn't even think about the lower left & right sides. I ended up checking all 4 corners, anyway, because I'm assuming that's what the SB calls for.

1. Are you folks checking all 4 corners?
2. Are you all removing paint before checking? Hope that's not a bad question, but the picture on the SB makes it look like you should be able to easily see a crack, but the text tells you to remove the paint before checking.

2009 RV-7A
220 hrs T.T.
ECI 0-360-A1A
Catto 3 blade
very little acro
almost always operated on paved runways
Does have notches
No cracks

[Kyle Boatright]

2001 RV-6
900 hrs
Wood Prop, O-320
Mild Acro - loops, rolls, rarely >4 G's.
Some (few) grass op's.
No notches.

No cracks.

[cdmiller]

RV-8 completed in 2006
IO-360 M1 with 9.2 to one and LS ignition
WW200 RV prop
1350 hours TT
Lots of acro; all <4 G's
Often push back on HS
No grass
No notches
No cracks; either SB

[Neal@F14]

1. Are you folks checking all 4 corners?
2. Are you all removing paint before checking? Hope that's not a bad question, but the picture on the SB makes it look like you should be able to easily see a crack, but the text tells you to remove the paint before checking.

I checked all 4 corners...

Two of my corners were blatantly obvious that there's no sign of even the remotest possibility of a crack, but two corners (upper starboard and lower port) had enough paint on them that I couldn't be absolutely certain... so I spent the time with a box of q-tips and various solvents to remove the paint and in the end there were no cracks to be found. I discovered that fully-cured, ten-year-old polyurethane paint and epoxy primer is awfully tough to remove with typical hardware store solvents... a mixture of non-chlorinated brake cleaner and MEK worked better than any other solvent alone, and it still took a long time and a lot of rubbing with q-tips. I wasn't about to use any harsh chemical paint stripper for fear of inducing corrosion.

[jrm7997]

I was just thinking about this very topic. What should you use to remove the corrosion resistant materials or paint to be able to do this inspection?

I've heard of using MEk but also biodegradable paint removers or aircraft type paint removers.

Not trying to hijack this thread but maybe make it part of it???????

Or is there another thread asking this question?

Thanks

[AHaury]

RV-6A
Built 2/21/2005
Third owner
512 hrs TT
Lycoming 0-320-01A
Hartzell HC-C2YL-1BF prop
No known acro
Typically hard surface use.
No notches
No cracks on either S.B.

[Rotorheadrob]

RV-8A
O-360 A1A
Hartzel CS
Finished 1999
+1100 hrs
Multiple Owners
Yes-Acro
Yes-grass
Yes-dirt
Yes-pavement
Yes-VFR
Yes-IFR
Yes-Formation Flying
Yes-long X-C trips
Yes-Hot Wx ops
Yes-Cold Wx ops

No Cracks. 😎👍🍺

[Danger Will Robinson]

RV-6
1230 Hrs TT
Built 1993
3rd owner for past 200 hrs
Slider
O-360 A1A
Hartzell C/S
Light acro
No towbar [that's going to change]
occasional rough turf runways
Notches
No Cracks

[tracy]

I wonder what the relation would be to those who are operating at gross weight a lot of the time? If the heavier weights are an issue, could the GW be reduced to do away with SB.

[Mark Burns]

RV-8A
O-360 A1A
Hartzel CS
Finished 1999
+1100 hrs
Multiple Owners
Yes-Acro
Yes-grass
Yes-dirt
Yes-pavement
Yes-VFR
Yes-IFR
Yes-Formation Flying
Yes-long X-C trips
Yes-Hot Wx ops
Yes-Cold Wx ops

No Cracks. 😎👍🍺

Notches??
I'm guessing "No"

Mark

[GaryK]

RV7A
2005
1135 hours
O 360
Hartzell BA CS Prop
95% pavement
Relief notches in all 4 corners
No cracks on either SB.

Gary
N715AB

[lostpilot28]

I checked all 4 corners...

Two of my corners were blatantly obvious that there's no sign of even the remotest possibility of a crack, but two corners (upper starboard and lower port) had enough paint on them that I couldn't be absolutely certain... so I spent the time with a box of q-tips and various solvents to remove the paint and in the end there were no cracks to be found. I discovered that fully-cured, ten-year-old polyurethane paint and epoxy primer is awfully tough to remove with typical hardware store solvents... a mixture of non-chlorinated brake cleaner and MEK worked better than any other solvent alone, and it still took a long time and a lot of rubbing with q-tips. I wasn't about to use any harsh chemical paint stripper for fear of inducing corrosion.

Thanks, Neal. I ended up using a lot of Q-tips and some lacquer thinner. Most of my empennage was primed with rattle-can primer, so it came off pretty easily.

I think my motive for asking the question about upper vs. lower cracks would be to see if anyone is seeing cracks on the bottom corners. Seems like the upper corners are getting all the attention...

[Terry Lutz]

RV-8
s/n 80462
200 TT
Completed 6/06
O-360-A1D
WW200RV - balanced
some grass
some acro
towbar
no notches
no cracks

[Mark Burns]

When I removed the top angle I was surprised to see fretting.
See photos below. The metal was flexing a good bit to cause this.
Its not deep and can be cleaned up with Scotch Brite.
I checked the botttom, both sides with dye penetrant and no cracks on the bottom.
In the photo the elevator is turned upside down.

I've cut two of the spar flanges back at an angle so far.
Surprisingly, this may be the most difficult part of the SB.

Mark



http://i1133.photobucket.com/albums/m599/mabbmbcb/Mobile%20Uploads/20140207_202950.jpg

http://i1133.photobucket.com/albums/m599/mabbmbcb/Mobile%20Uploads/20140207_202801.jpg

[bret]

I finished taking mine apart this morning, if you really look at it, this mod is going to add a great deal of strength to the forward spar. I can see where the flimsy sheet metal spar could flex easily during non SAL flight, stalls, spins ect.

[bret]

I wanted a little more room so this is how I did mine.
http://i895.photobucket.com/albums/ac158/bret496/DSC04417_zpsb3634672.jpg

[floridawing]

Thank you for the pictures and post! It is very much appreciated!

[gerrychuck]

I was just thinking about this very topic. What should you use to remove the corrosion resistant materials or paint to be able to do this inspection?

I've heard of using MEk but also biodegradable paint removers or aircraft type paint removers.

Not trying to hijack this thread but maybe make it part of it???????

Or is there another thread asking this question?

Thanks


I did my initial inspection yesterday, but had a tiny niggling doubt about one corner. Went back today with a can of lacquer thinner from Canadian Tire (MEK and toluene). Cleaned the 10 year old overspray and primer very easily; only had to use 2 Q-tips to get down to shiny metal around the notch. Glad I did; my hi-res photos after cleaning leave no doubt that there is no crack, and the cleaning process only took me about 5 minutes.

[David-aviator]

I did my initial inspection yesterday, but had a tiny niggling doubt about one corner. Went back today with a can of lacquer thinner from Canadian Tire (MEK and toluene). Cleaned the 10 year old overspray and primer very easily; only had to use 2 Q-tips to get down to shiny metal around the notch. Glad I did; my hi-res photos after cleaning leave no doubt that there is no crack, and the cleaning process only took me about 5 minutes.

Ten year old airplane and no cracks....some 15-20 years old and no cracks....newer machines are not passing muster. Maybe the aluminum is being imported like so many other inferior products.
Something has changed.

[Jaypratt]

The Borrowed Horse has no cracks! Well the pilot is a "Butt Crack" but that is another story,:rolleyes:

RV8 2007

550 hours since new,
No acro,
A few scary landings,,,, :eek:
Lots of grass operations.
No EFIS, No Glass panel, :cool:
No notches in HS spar.
No cracks in H/S spar web
No cracks in rudder or elevator doublers :D

[scottg]

RV-6A completed 1997, 1993 tail kit
Original owner/builder
1,100+ hrs (tach)
O-320, Hartzell C/S
Mild Acro for the first 5 yrs- loops, rolls
First 14 years on grass, last 2+ on pavement
No notches
No cracks on both SBs

[Rotorheadrob]

Notches??
I'm guessing "No"

Mark

Correct, No Notches.

No Cracks.

Older kit.

Dispite this SB, total confidence in these stout planes.

An outstanding use of VAF community. Pulling together to determine cause and assist one another sort this and other issues. 😉👍

[gerrychuck]

Ten year old airplane and no cracks....some 15-20 years old and no cracks....newer machines are not passing muster. Maybe the aluminum is being imported like so many other inferior products.
Something has changed.

Perhaps, but my plane only has 375 TT despite being 10 years old; not a high hour bird at all.

[jbDC9]

Finally got around to checking mine today; no cracks.
RV-8
2003 vintage tail kit
1090 hrs
No notches.
Some grass, easy acro.
O-360 180hp, CS prop.

[John RV8]

Finally Did my inspection

No Notches - No Cracks
Tail section built circa 2003, plane not finished until 2011
Total time 175 hours
some acro
some grass
lives on rough paved strip (52F)
rarely push on tail, (has retractable handles) so no need
Composite constant speed prop (MT)
180 HP

[Tom Schad]

Inspected me RV-8 yesterday. No cracks. Superior O-360 A1A Hartzell. No acrobatics mostly flown off of grass. Not a prepunched kit. About 500 TT. Also, checked son's RV 6. About 150 hours TT. Lycoming O-320 E2D no acro. Old slow built kit. Also flown off of grass. Jay dropped in while I had both airplanes apart and confirmed my findings. Guess, we dodged the bullet for now...

[nzrv8]

I guess I'm lucky, I built a second HS as I wasn't happy with the first.. And as of last month it is ready for priming and final assembly. I will be incorporating the SB fix now.

[Bob Gordon]

At 694.1 hours time in service I found no cracks in either the horizontal stabilizer or elevator as mentioned in their SBs. No aerobatics, hard surface runways. No notches on this 1997 tail kit.