Small rudder cracks near front edge

[IslandAV8R]

I’m a new owner of 16 year old RV 7A with a little over 800 hours, and noticed small cracks near the front edge of the rudder. Picture attached. They are only on the right side, and are all near the first rivet. Only one is by a hinge. Is it safe to fly the airplane? Is this typical? Any repair recommendations? Thanks.

 

[Taltruda]

That’s pretty typical.. Probably caused by the builder not folding the trailing edge enough and instead they riveted the spar in place with the internal stresses of the skin not fully folded. (I realize -7s now have a three piece rudder now, but I believe originally they had a folded trailing edge rudder off the -8, that’s what I’m assuming this is?) it’ll probably never grow, you could stop drill and make little triangle patches connecting the spar to the skin and internal stiffener.. and eventually build a replacement rudder, but I would think its still ok to fly. When in doubt, email Vans and don’t take the free advice of a stranger on the internet though.

 

[Richard Connell]

That’s pretty typical.. Probably caused by the builder not folding the trailing edge enough and instead they riveted the spar in place with the internal stresses of the skin not fully folded. (I realize -7s now have a three piece rudder now, but I believe originally they had a folded trailing edge rudder off the -8, that’s what I’m assuming this is?) it’ll probably never grow, you could stop drill and make little triangle patches connecting the spar to the skin and internal stiffener.. and eventually build a replacement rudder, but I would think its still ok to fly. When in doubt, email Vans and don’t take the free advice of a stranger on the internet though.

It’s not unheard of. I’d say these are because the leading edge wasn’t rolled enough though. A 7 of this vintage should have a riveted TE. It may not though. What’s the SN?

Under formed TEs tend to result in cracks at the rear of the stiffener first.
If it was one, maybe I’d stop drill it. But 4 in the same plane is another issue.
I’d defer to the factory for advice.

My favorite quote from the builders manual:

“The problem with small cracks is that they soon become large cracks, one piece of aluminum becomes two pieces, etc. Obviously, we do not want this happening in our airframe, particularly when separated from solid earth by a lot of very thin air.”

 

[plehrke]

If you search for “rudder cracks” you will find many threads. Mostly, I think, they involve RV-6/6As as they had 0.016 thick skins. Here is one on the RV-7 as well. Many just stop drill the cracks but post #7 in following link shows a repair.

Cracks in Rudder Skin

2014 RV7- 537 hours, cracks in .016 skin of rudder at stiffener to spar. Looking for possible avenues to repair these cracks. 1. Clear packing tape & stop drill-observation (gleaned from searching forum) 2. Click bond patch (gleaned from searching forum) 3. Patch over skin after stop drilling...

www.vansairforce.net

Those cracks are due to not putting enough curl on the leading edge and force fitting the skins to overlap. The crack is due to the design does not tie skin stiffeners to the spar and the skin is too thin and flexible to transfer the load.

 

[scrollF4]

Question: Have these cracks appeared in RV-8 rudders? Those have folded trailing edges, and the skin sheet is thicker.

 

[bjdecker]

Question: Have these cracks appeared in RV-8 rudders? Those have folded trailing edges, and the skin sheet is thicker.

Sid -

Yes; 200 hours on my 0.020” skinned, RV-8. Rudder I under-rolled the leading edge and had a less-than-good-break on the front edge of one stiffener.

-Brian
“Showplane”

 

[robertahegy]

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My 2002 Vintage 7A tail had the riveted trailing edge. I think it was around 2000 or 2001 that they switched to this rudder. Proper rolling was important.