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

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.

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.
 
Hair Style?

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
 
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.
 
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
 
New Horz Stab...Install?

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

No cracks.
 
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?
 
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.
 
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.
 
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.
 
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.
 
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
 
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.
 
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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.
 
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.
 
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
 
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.
 
RV 8

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
 
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.
 
Ugh!

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

9FF186A4-B780-42C9-A0B7-DF8B3003A676_zpsxzasxbrx.jpg


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 :/
 
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RV-8
165 hrs TT
IO-375
Whirl Wind 200RV prop (balanced)
Paved runways
Light acro <4 Gs
No notches
No cracks
 
Early RV-6, no cracks

Inspected my early model 6 (kit purchased in 1989, finished in 1999). 980 hrs; 0320, MT fixed pitch, light acro.... no cracks.
 
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.
 
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.
 
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
 
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.
 
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
 
RV8 with 500 hours. Plenty of acro and mountain turbulence. No unimproved fields, but lots of rough asphalt. No notches or cracks.
Chris Hukill
 
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
 
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.
 
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


HS3 by bavafa1, on Flickr
 
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


HS3 by bavafa1, on Flickr
Interesting about the position of this "notch". How would one see any potential cracking behind that rib flange? Tough dilemma.
 
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?"
 
SB's Completed for now

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
 
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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.
 
Tried to order replacement HS parts and got a surprise

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?
 
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