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Wing Cracks

K

kklewin

Well Known Member
Just noticed a 5 in horizontal crack along the trailing edge of the right wing perfectly in line w the aft rivet line (basically connects the rivets) on top of aft spar flange, just before the flap. Awaiting a response from vans engineering, but anyone had a similar issue ? Solution? It’s just right of passenger reinforced walk area. We are extremely careful where people walk and really haven’t taken many people up other than wife and adult son that are diligent on walking on walk area, so be very surprised if it’s from that. Flying for 20 yrs, 6A, 750 hrs, no acro, max lifetime Gs has been below 3, no hard landings, incidents, or accidents, quick build wing ( I didn’t rivet that area), one owner and original builder. Thanks in advance.

Cheers!

Kurt
 
Wow.....never heard of that one. Keep us informed, my RV-6 is older and higher mileage than your plane......

Is this just ahead of where the top wing skin overhangs the flap? If so, there may be some flexing occurring in this unsupported area which started the crack.
 
kklewin said:
Just noticed a 5 in horizontal crack along the trailing edge of the right wing perfectly in line w the aft rivet line (basically connects the rivets) on top of aft spar flange, just before the flap. Awaiting a response from vans engineering, but anyone had a similar issue ? Solution? It’s just right of passenger reinforced walk area. We are extremely careful where people walk and really haven’t taken many people up other than wife and adult son that are diligent on walking on walk area, so be very surprised if it’s from that. Flying for 20 yrs, 6A, 750 hrs, no acro, max lifetime Gs has been below 3, no hard landings, incidents, or accidents, quick build wing ( I didn’t rivet that area), one owner and original builder. Thanks in advance.

Cheers!

Kurt
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Photos please! This is new (to me).
 
The current owners of a 7A I sold some 15 years ago found (at approx 1800 hrs) what sounds like an identical crack as you described, linking 5 rivets along the rear spar starting at edge of the wing walk.
Vans Tech said this issue was not common, only a few reported, probable cause was foot steps outside the wing walk area, the fix is replace top inboard wing skin.
A nasty job replacing that skin, but can be done with the wing on the plane, if you have a helper with long skinny arms.
 
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The skin overhang and flap "up" is a 100%contact area, and I could see how this would occur in a mis-rigged flap, as the skin is flexed up by the flap leading edge if the flap skin isn't bent just right or the flaps are sitting higher than they should. I would take a good look at that while operating the flaps.
 
Thought of that but in our case trailing edge skin had no tension on the flap in any position.
Weird crack for sure & as a few others have experienced it, would like to know the actual cause. I always thought the doubled wing walk area should be extended out to the next rib.
 
Could it be the way the prop wash is hitting that panel under some specific engine/prop/rpm combination? Some kind of resonance? Maybe that would explain the extremely rare occurrence.
 
Jjackh10 said:
Could it be the way the prop wash is hitting that panel under some specific engine/prop/rpm combination? Some kind of resonance? Maybe that would explain the extremely rare occurrence.
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I would bet on a flap that is pressing too hard on the upper skin, passenger abuse, or a combination of the two.
 
Kyle Boatright said:
I would bet on a flap that is pressing too hard on the upper skin, passenger abuse, or a combination of the two.
Click to expand...
I could buy that. The OP did state that he's only carried a few passengers and they were disciplined where they stepped. And the plane only has 750hrs. Certainly not enough flap cycles to induce fatigue cracking. So the pressure on the skin from the flap would have to fluctuate and frequently. Hence my thinking about propwash in that area. Just trying to understand it in my head.
 
Vans opined that maybe pax walking on that area (less likely as I mainly fly solo)’ or more likely (flaps putting pressure on top wing skin). It was a quick build wing (2002), and it seems more a plausible there was friction here. We never made any flap movement above 85 KIAS, but could still be fatigue from flap movements over 20 yrs. Solution is either wing skin replacement in this area, or a crack repair (patch) IAW AC 43.13. Leaning to the repair in the short term and replacement in the long term.

Kurt
 
If I, the most computer inept person on the forum can do it you certainly ought to be able to too

Click on the little picture icon I circled in red and click on the picture in your files and that’s all shows up in your post just like this.
51EEF38C-BB70-4C07-9421-78CCADBA57B1.jpeg
 
My 6 is from way back when you had to lay out all the holes, drill and deburr, I have 2000+ hours on it and Manual Flaps (would never change for electrics). I also have full contact with upper skin an no signs of skin cracking. My question is "are all the ones who have this problem pre punch skins?" Electric flaps?
 
Dragon Master said:
My question is "are all the ones who have this problem pre punch skins?" Electric flaps?
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Sorry, can’t supply a picture. On the 7A (my first build) the crack started from the first rivet outboard of the wing walk doubler. It extended between the next 5 rivets along the rear spar.
Prepunched/than match drilled. Electric flaps.
 
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