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-   -   SB 18-02-02 Potential cracking in the horizontal stabilator front spar (https://vansairforce.net/community/showthread.php?t=157839)

DeltaRomeo 02-15-2018 04:42 PM

SB 18-02-02 Potential cracking in the horizontal stabilator front spar
 
Issued today:

RV-12. Before further flight.

http://www.vansaircraft.com/pdf/sb18-02-02.pdf

"Inspect stabilator front spar for cracks. If cracks are not present the aircraft may be returned to service until the next 100 hour or annual inspection, when this service bulletin should be performed before further flight. If cracks are found, complete this SB immediately. Kits under construction should perform this SB prior to stabilator attachment or first flight."
v/r,
dr

moosepileit 02-15-2018 05:01 PM

RV-12
 
Model RV-12

MrSparkle 02-15-2018 08:21 PM

Inspection for cracks
 
I assume that the only way to inspect the stabilator's front spar for cracks is to remove the stabilator and the hinge brackets. Agree/disagree?

Ian Heritch
RV-12 N417E

alexe 02-15-2018 09:21 PM

Agree. At that point you might as well do the fix rather than waiting to do it at the next conditional inspection. This is not going to be fun!
Alex

E. D. Eliot 02-15-2018 09:26 PM

Want to comply!!
 
I do appreciate this SB and all of the work that the technical staff at Van's must have put into it. Would have liked to order tonight but can't because I'm not sure which new parts need to be ordered. I'll call tomorrow along with many of you.

Recommendation to Van's --- please add a short note that lists the parts need in order to comply. If Van's did that this time then I apologize profusely.

Thanks again for the SB.

rgmwa 02-15-2018 11:08 PM

Quote:

Originally Posted by MrSparkle (Post 1239856)
I assume that the only way to inspect the stabilator's front spar for cracks is to remove the stabilator and the hinge brackets. Agree/disagree?

Ian Heritch
RV-12 N417E

That's if you can actually see any cracks. They would be very easy to miss judging by the photos in the SB. I wonder what prompted Vans to look there, although I guess it's an obvious potential trouble spot when you think about it. This won't be a fun job, but if you have to pull everything apart to check you might as well bite the bullet and do the fix at the same time.

Harvey rv12 02-15-2018 11:33 PM

Vans SB?s usually have a ?synopsis? detailing what prompted the bulletin.
This SB doesn?t say much. Would be interesting to learn how this was discovered.

skydiverlv 02-16-2018 07:21 AM

I like the 6hr labor estimate. That indicates how old and slow I am.:D

Piper J3 02-16-2018 08:25 AM

I wonder if Van's will supply parts free-of-charge for this SB like they did for fuel tank and landing gear?

TomVal 02-16-2018 09:16 AM

Since the stabilizer has to be pulled, if you haven't already done so, might as well complete SB 16-08-01 - Stabilizer Bearing Inspection.

rvbuilder2002 02-16-2018 09:56 AM

Answers to some of the questions.....
 
The first discovered instance of cracks was by maintainers of an S-LSA operated by a flight school.

Follow-on investigation found cracks in two of Van's Aircraft's demonstrator RV-12's.

The stabilator must be removed from the airplane and the hinge brackets removed from the stabilator to gain visual access to the area potential to crack (the fwd web of the box spar under the hinge brackets) .

The option was given to delay the installation of the updated parts if no cracks are discovered, to allow owners some flexibility if they can't do the parts installation immediately because of lack of skills (weren't the aircraft's builder), haven't yet obtained the needed parts, etc.
In most cases, it would make sense to just install the new parts while the stabilator is removed for the inspection.

It may be difficult to detect cracks depending on the level of crack development (how big they are) and surface condition (primer or paint coatings, etc.). This is another reason it might make sense to just install the parts regardless of what the inspection results are.

I don't know how the cost of parts is being handled. You will have to ask about that when ordering the kit.

There is a variability in the size of cracks that have been discovered so far.
The red prototype (N412RV) with well north of 2000 flying hrs had very small cracks that were at first difficult to detect. The photos in the S.B. are from that aircraft. Another aircraft with only 1/3rd as many hrs had larger cracks.

It is only speculation, but it is thought that an RV-12 that has sat outside in wind a lot with unrestrained controls (I.E., stabilator banging against the up and down stops because of wind movement) could be more susceptible to cracks.

BTW
An evaluation of the problem after initial report, do an FEA model analysis, design of a modification, production of prototype parts, beta installation of the new parts on two different stabilators and writing of the install instructions and SB document and publishing it, were all done in less than 3 weeks.

JwWright57 02-16-2018 12:00 PM

for once procrastination paid off, I'm at the point in my build where this is not a big deal. Also, the hinge brackets did seem a little light, so i'm glad to see they are being beefed up!

JwWright57 02-16-2018 12:01 PM

Kudos to Vans for getting this out so quick

Jshepherd 02-16-2018 12:16 PM

Parts are on the web store $20 plus shipping

Phantom30 02-16-2018 12:50 PM

I kind of wonder if “over-tighting” of control cables might have something to do with this problem....just my trouble shooting mind @ work!

When adjusting and stretching stab cables; I tighten till cable slap stopped which was not as tight as gauge pressure was suppose to be... My concern being the fiber rollers the cables ran over.

Scott....you can jump in here to slap my hand anytime��

Phantom30 02-16-2018 12:59 PM

Quote:

Originally Posted by TomVal (Post 1239969)
Since the stabilizer has to be pulled, if you haven't already done so, might as well complete SB 16-08-01 - Stabilizer Bearing Inspection.

Ditto on that....going to replace bearings and install Stab fix parts all at one time to satisfy annual tail end inspection...

rvbuilder2002 02-16-2018 01:04 PM

Quote:

Originally Posted by Phantom30 (Post 1240020)
I kind of wonder if ?over-tighting? of control cables might have something to do with this problem....just my trouble shooting mind @ work!

When adjusting and stretching stab cables; I tighten till cable slap stopped which was not as tight as gauge pressure was suppose to be... My concern being the fiber rollers the cables ran over.

Scott....you can jump in here to slap my hand anytime��

Not intended as a hand slap, but I don't think that has anything to do with it.

The load cycle that will cause the most flex in the structure and have an influence on causing the fatigue cracks to occur is the load induced when the stabilator bumps the up or down travel stop.

BTW, the fiber pulleys used are standard aircraft components.... same as used in Cessna, etc.
The cable tensions specified for the RV-12 are very similar to what is used in many other aircraft that use the same pulleys.

TLKRV12 02-16-2018 01:51 PM

cost of parts for SB 18-02-02
 
Cost of the parts for SB 18-02-02 $20 USD + shipping

epaslick 02-16-2018 10:20 PM

Quote:

Originally Posted by JwWright57 (Post 1240003)
for once procrastination paid off, I'm at the point in my build where this is not a big deal. Also, the hinge brackets did seem a little light, so i'm glad to see they are being beefed up!

I'm right there with you. My stabilator is build but not installed on the tailcone. Counting my blessings.

Top Cat 02-17-2018 07:11 AM

I’m a bit confused ( fairly common these days).

I ordered the 18-02-03 kit. See the home page on Vans website for SB details plus click on to order kit ($20 plus shipping).

However, reading the SB 18-02-02 at the end it says to order the 18-02-02 kit which i can’t find on the Vans site.
My RV-12 is 2014 SLSA.

What am I missing?

Top Cat 02-17-2018 07:21 AM

Quote:

Originally Posted by Phantom30 (Post 1240022)
Ditto on that....going to replace bearings and install Stab fix parts all at one time to satisfy annual tail end inspection...

Is there an ?SB kit? forSB 16-08-01 ? I didn?t see it on Vans site and i was thinking if the stab has to come off might as well get all this done at one time.
Thanks for any help.

Jamesey 02-17-2018 08:04 AM

It?s There
 
Quote:

Originally Posted by Top Cat (Post 1240144)
I?m a bit confused ( fairly common these days).

I ordered the 18-02-03 kit. See the home page on Vans website for SB details plus click on to order kit ($20 plus shipping).

However, reading the SB 18-02-02 at the end it says to order the 18-02-02 kit which i can?t find on the Vans site.
My RV-12 is 2014 SLSA.

What am I missing?

$10.00 plus shipping. It?s on the website. However I can?t find F-1204M as referred to in Notification January 24 2018.

Piper J3 02-17-2018 08:06 AM

Quote:

Originally Posted by Top Cat (Post 1240144)
I?m a bit confused ( fairly common these days).

I ordered the 18-02-03 kit. See the home page on Vans website for SB details plus click on to order kit ($20 plus shipping).

However, reading the SB 18-02-02 at the end it says to order the 18-02-02 kit which i can?t find on the Vans site.
My RV-12 is 2014 SLSA.

What am I missing?

I ordered both this morning from Van's Aircraft Web Store...

Part Number: SB 18-02-02
Quantity: 1
Unit Price: 20.00

Part Number: SB 18-02-03
Quantity: 1
Unit Price: 10.00

redbaron 02-17-2018 02:39 PM

SB 18-02-02 and SB18-02-03
 
Part Number Sb 18-02-02 is for Ser Bul 18-02-02 $ 20.00
Part Number Sb 18-02-03 is for Ser Bul 18-02-03 $10.00
this from the last page of the ser Bul's

alexe 02-17-2018 03:03 PM

Just a quick data point....

I removed the stabilator this morning and did the required inspection. Cleaned things up and did a dye penetrant test. No cracks were detected in the spar. I also inspected the AST, no cracks there either. I have 240 hours on the plane, always hangered.

I ordered both part kits (Stabilator and AST) yesterday. Hopefully they will arrive next week and I can start getting the plane back together.

Alex

gblwy 02-18-2018 05:42 AM

Tools
 
Hoping the bits get to the UK without too much delay. Please...

Having read the instructions I made a list of tools I plan to have to hand:

camera (to take pics)
screwdriver
socket set
tape
wire (eg locking, but string would do)
ruler
sharpie (sharp!)
center punch
primer etc (if you use that)
#30, 40 drill bits and drill
something to deburr holes
countersink tool and bits
rivet squeezer and maybe the wedge
inspection light, magnifying glass (maybe dye penetrant kit)
1/16 punch or old #40 drill bit!
pop riveter
hacksaw/dremel for separating parts
file/grinder for hinge angle prep
superglue for washers

coffee, lunch, hopefully not supper too!

I'll have to remember how to use the various tools. It's been 7 years...

Cheers...Keith

rgmwa 02-18-2018 06:05 AM

Quote:

Originally Posted by gblwy (Post 1240325)
Hoping the bits get to the UK without too much delay. Please...

Having read the instructions I made a list of tools I plan to have to hand:

camera (to take pics)
screwdriver
socket set
tape
wire (eg locking, but string would do)
ruler
sharpie (sharp!)
center punch
primer etc (if you use that)
#30, 40 drill bits and drill
something to deburr holes
countersink tool and bits
rivet squeezer and maybe the wedge
inspection light, magnifying glass (maybe dye penetrant kit)
1/16 punch or old #40 drill bit!
pop riveter
hacksaw/dremel for separating parts
file/grinder for hinge angle prep
superglue for washers

coffee, lunch, hopefully not supper too!

I'll have to remember how to use the various tools. It's been 7 years...

Cheers...Keith

... and maybe a wee dram to celebrate a successful operation?. ;)

gblwy 02-18-2018 06:55 AM

A year or so ago I sold a half share in my RV12 to a flying partner. I asked him whether he wanted to buy the front half or the back half. He elected to take the back half. Result!!! I'll have the dram now ;-)

I saw the feedback from the related AST mod. I, too, am happy that a potential problem has been spotted and a fix made available. $30 for both fixes and maybe two days effort to implement. And a few more bucks for consumables and couple more days to do an annual inspection. A very reasonable outlay of cash and labour for a year of flying.

Cheers...Keith

ExErcoupeGuy 02-18-2018 12:52 PM

Quote:

Originally Posted by alexe (Post 1240248)
Just a quick data point....

I removed the stabilator this morning and did the required inspection. Cleaned things up and did a dye penetrant test. No cracks were detected in the spar. I also inspected the AST, no cracks there either. I have 240 hours on the plane, always hangered.

I ordered both part kits (Stabilator and AST) yesterday. Hopefully they will arrive next week and I can start getting the plane back together.

Alex

My RV 12 is here at Marco Island from Marysville, Ohio for the month and I find myself grounded by these SB, especially the stabilator spar issue. Fortunately, a very kind and experience A & P is ready to assist in doing the inspection once the kits (in case cracks are found) and my build book arrive. The text of the SB 18-02-02 is lacking in clarity (at least for me) but the folks at Van?s build assist confirmed my reading that step one is removal of the stabilator and conducting an inspection (my folks here at Marco can do a magnaflux) and if no cracks are found re-install the stabilator and then do the kit at next annual/100 hrs. Since my shop in Delaware Ohio is well versed in the RV 12 if all is well I?ll have them do it there. My aircraft, first flown the end of 2013 now has 200 hours and has always been hangared. So I am hoping for the best. Was the inspection fairly easy to perform once the stabilator was removed? Thank you for any input, words of encouragement.

alexe 02-18-2018 04:53 PM

ExErcoupeGuy,

Yes, the inspection itself is fairly easy to do. Once the stabilator is off the airplane, remove the the hinge brackets located on the front side of the stabilator spar. The service bulletin has good pictures of what to look for in that area, however, you will probably have to remove paint in the area with some fine sandpaper before you can really make a thorough inspection. Hope you don?t find any cracks so you can get your plane back home in a timely manner.

It take it that your airplane is a S-LSA, not an E-LSA?

Alex

alexe 02-18-2018 05:02 PM

ExErcoupeGuy,
I just sent you a PM.
Alex

ExErcoupeGuy 02-19-2018 06:11 AM

Quote:

Originally Posted by alexe (Post 1240461)
ExErcoupeGuy,

Yes, the inspection itself is fairly easy to do. Once the stabilator is off the airplane, remove the the hinge brackets located on the front side of the stabilator spar. The service bulletin has good pictures of what to look for in that area, however, you will probably have to remove paint in the area with some fine sandpaper before you can really make a thorough inspection. Hope you don?t find any cracks so you can get your plane back home in a timely manner.

It take it that your airplane is a S-LSA, not an E-LSA?

Alex

N32SB is E-LSA. Has about 200 hours on it. Always hangared. Built in 2013 but didn?t fly much until my seller, a great Ret. AF General, bought it from the builder. The Gen. is beyond meticulous with his aircraft; e.g., all SB?s applicable were complied with by installation of Van kits obviating further inspection. This is exactly what I will do ? but since I?m in the field in Marco Island FL away from my Ohio shop (Rotax Certified and experienced in LSA, esp. RV 12?s Shamrock Aviation Services, Shane Young, in Delaware, OH) ? I will defer kit installs if inspection passes. I am very careful to cage the yoke and install rudder gust locks when it?s on a ramp and not hangared back home. Thank you so much for your advice and help.

joedallas 02-19-2018 11:15 AM

Before further flight ??
 
Before further flight ??

If you have less than 100 hours why would you need to check before further flight if it is OK to fly it for 100 hours after you check it ?

Unless Vans thinks that the crack may be associated with the bending process of the HS-1202 Spars ?

I think this is possible ?

If there is no cracks I wonder if the patch on top of the skin is necessary?
This will look like a Patch in my View.
Joe Dallas

rvbuilder2002 02-19-2018 12:12 PM

Quote:

Originally Posted by joedallas (Post 1240625)
Before further flight ??

If you have less than 100 hours why would you need to check before further flight if it is OK to fly it for 100 hours after you check it ?

Unless Vans thinks that the crack may be associated with the bending process of the HS-1202 Spars ?

I think this is possible ?

If there is no cracks I wonder if the patch on top of the skin is necessary?
This will look like a Patch in my View.
Joe Dallas

There are a lot of different things that could induce the repetitive loads that could cause cracking (a toddler sitting for hours banging the stick against the stops :rolleyes:, etc.) Since Van's has no way of knowing how the airplane has been treated regardless of the # of hours, it is specified that all be checked.
The premise is that if no cracking was induced during the first 100 hours, then it is likely that nothing serious would happen after another 100 hrs.

The patch on the top of the AST skin has nothing to do with the S.B. for the stabilator spar. They just happened to be published at about the same time.

I am pretty sure the AST S.B. is clear in saying that the skin doubler is only required if pre-existing cracks are found at inspection. Otherwise just the change in ribs is required.

alexe 02-19-2018 12:37 PM

Scott,

Regarding the stabilator SB, does the HS-01231C gusset (figure 4) fit beneath the skin or on top?

Thanks,
Alex

DonFromTX 02-19-2018 02:49 PM

I too am having some difficulty visualizing all this from the drawings.
Photos from the first people will be valuable.
Quote:

Originally Posted by alexe (Post 1240662)
Scott,

Regarding the stabilator SB, does the HS-01231C gusset (figure 4) fit beneath the skin or on top?

Thanks,
Alex


joedallas 02-19-2018 03:00 PM

Scott

Figure shows the patch on the top adding as shear connection to the hinge bracket , in my view

Joe Dallas






Quote:

Originally Posted by alexe (Post 1240662)
Scott,

Regarding the stabilator SB, does the HS-01231C gusset (figure 4) fit beneath the skin or on top?

Thanks,
Alex


Mel 02-19-2018 03:01 PM

Quote:

Originally Posted by alexe (Post 1240662)
Scott,
Regarding the stabilator SB, does the HS-01231C gusset (figure 4) fit beneath the skin or on top?
Thanks,
Alex

My interpretation is that both figure 4 and figure 8 clearly show the gusset to be on top of the skin. Also Step 27 states that no spacer is needed under the 2 inboard, aft rivets. If the gusset were to be under the skin, that statement would not be necessary.

rvbuilder2002 02-19-2018 03:32 PM

Quote:

Originally Posted by Mel (Post 1240691)
My interpretation is that both figure 4 and figure 8 clearly show the gusset to be on top of the skin. Also Step 27 states that no spacer is needed under the 2 inboard, aft rivets. If the gusset were to be under the skin, that statement would not be necessary.

Mel is correct.

rvbuilder2002 02-19-2018 03:37 PM

Quote:

Originally Posted by joedallas (Post 1240690)
Scott

Figure shows the patch on the top adding as shear connection to the hinge bracket , in my view

Joe Dallas

Since you weren't using part numbers I assumed you were talking about the doubler (patch) that goes over cracks on the antiservo tab (a different S.B.)

The doubler on the top and bottom of the stabilator is an important component for longevity and crack avoidance.

Call it a patch if you want, but it is a doubler.... just like all of the triangular doublers that are on the exterior of the fuselage belly.


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