SB 00036 (cracked horiz stab spar) Installation Notes

[Sam Buchanan]

As the service bulletin kits are arriving in the field and installations occur there may be information that is useful for those contemplating or planning the repair. Please post any details you encounter with the installation that need to be shared.

[Sam Buchanan]

As is customary for Vans, all the rivets for the SB00036 kit are shipped in one little bag. Included are the driven rivets for reattaching the skin.....and TWO sizes of Cherry Max rivets.

A...uhh....friend was installing the kit on his non-cracked pre-punched RV-6 stab and failed to take note of the two sizes of pulled rivets (even though this detail is in the documentation....). A quick check with the borescope after riveting the hinges on one side of the stab revealed a major uh-oh. Three of the pulled ends looked good but five were atrocious.

It then dawned on my sometimes dense friend that the longer rivets intended for use with the doubler on the forward side of cracked spars had been used with the non-cracked and undoubled spar. So I, uh, my friend got to drill out the Cherrys with a #40 bit so the heads could be knocked off.

Separate the Cherry Max rivets when you receive your kit and put the ones you don't need in an unsafe place......

[PCHunt]

Thank you, ......ummm "friend", for your report!

[Traash]

That's a huge heads up. Wondered why I got 32 cherry max.

[Sam Buchanan]

Originally Posted by Traash

That's a huge heads up. Wondered why I got 32 cherry max.

Yep, the rivets are only one dash number apart, anything less than a very close look and they all appear the same. Cherry Max's need to be the exact correct length to set properly and provide rated strength.

[srbooher]

After borescoping my horiz spar bracket repair I found that half of my Cherry Rivets had the mandrel recessed into the rivet head, and sticking out of the spread rivet (see attached photo). The Vans engineers say this is unacceptable because if the mandrel should vibrate out there is little strength to the rivet. This problem apparently exists with the RV-12 Cherry Max rivets as well. There is a Vans YouTube video on dealing with the problem, and the engineers recommend heating the rivet while soaking in lubricant to “prep” it for installation. This means I need to remove the elevators again, drill out the bad rivets, and reinstall.

[Taltruda]

Are you guys doing the repair on the plane? Or is everyone pulling the HS to work on the bench?

[PaulvS]

Originally Posted by Taltruda

Are you guys doing the repair on the plane? Or is everyone pulling the HS to work on the bench?

I'm planning to do it on the plane, with a sawhorse supporting the tail cone. The height is convenient and everything is just as easy to get to as if it was done on the bench (where it would also need to be held steady somehow).

[PaulvS]

Originally Posted by srbooher

After borescoping my horiz spar bracket repair I found that half of my Cherry Rivets had the mandrel recessed into the rivet head, and sticking out of the spread rivet (see attached photo). The Vans engineers say this is unacceptable because if the mandrel should vibrate out there is little strength to the rivet. This problem apparently exists with the RV-12 Cherry Max rivets as well. There is a Vans YouTube video on dealing with the problem, and the engineers recommend heating the rivet while soaking in lubricant to “prep” it for installation. This means I need to remove the elevators again, drill out the bad rivets, and reinstall.

Bit of a pain in the butt that. I guess we should order extra rivets just in case.

[Sam Buchanan]

Originally Posted by srbooher

After borescoping my horiz spar bracket repair I found that half of my Cherry Rivets had the mandrel recessed into the rivet head, and sticking out of the spread rivet (see attached photo). The Vans engineers say this is unacceptable because if the mandrel should vibrate out there is little strength to the rivet. This problem apparently exists with the RV-12 Cherry Max rivets as well. There is a Vans YouTube video on dealing with the problem, and the engineers recommend heating the rivet while soaking in lubricant to “prep” it for installation. This means I need to remove the elevators again, drill out the bad rivets, and reinstall.

That looks familiar.......

I decided to forget the Cherry Max rivets and drilled out the rivets on the bottom skin so I could access the front of the spar. It only took a few minutes, wish I had done that first instead of messing with the Cherry's. Driving the hinge rivets went well and now I know the hinges are secure.

My A&P friend told me the Cherry's can't be drilled out but I was able to use a #40 drill to remove enough of the mandrel so the heads could be popped off with a flat drift and hammer without damaging the hinges.