Small weird cracks, lower-rear of gear tubes

born2fly · #1 03-15-2009, 01:01 PM

Does anyone have experience with cracks in engine/gear mount?

RV6, 920 hours, no hard landings or anything:

Small hairline cracks (1/2") at BOTTOM REAR of gear leg attach tube welds.
The weird thing is that this area is under compression-load (gear legs slant aft and outward), and is under tension only when the gear is hanging while airborne. No apparent way for a stress to create a crack.

The cracks are in the center of the welds, about 2" above the end of the gear-leg tube on the firewall side and slightly outboard. They look a lot like they could be fabrication-based due to weld shrinkage. There is a lot of welding and metal and beads in that area.

These cracks are not in any engine-stressed area, they're at the back of the bottom of the gear leg tube.

Any information or thoughts?

John Courte · #2 03-15-2009, 09:46 PM

Are you sure those cracks go all the way through the metal or is it just the powder coating that's cracked?

JoeBlank · #3 03-15-2009, 10:07 PM

Does your engine mount have small triangular gussets between the leg socket, vertical tube, and horizontal tube? Some of the very early mounts were not manufactured without those gussets and there was issues with cracking. The gussets solved the problem and all mounts now have them. Send pics to Vans for confirmation. They can also get you the parts. They can be welded in the field, but necessitates engine mount removal to do it.

born2fly · #4 03-15-2009, 11:45 PM

The mount is of ~1999-2000 vintage, and it has several bracing tubes and filler gussets in the area. I'll try to get some pix.

Sure seems like a rarity, and I haven't beat it up to speak of, just a few rough strips this past year. There's guys out there that run off of grass and gravel all the time, haven't heard them talk about this kind of problem.

Yes, the cracks are in the metal, the paint has been removed. (A somber note to all hopefuls: powder coat is more flexible than metal and will crack last. If you see a crack, it's there.)

born2fly · #5 03-16-2009, 03:42 PM

Talked to Van's today, and was told cracks in this area are "very common".

Apparently, my engine mount was made prior to the addition of the reinforcing gussets in the gear-leg socket area.

Does anyone have any pictures of a late-model mount (after 2002), showing the gussets at the gear leg sockets? I'd like to understand how the fix works and what I'll need to do.

JonJay · #6 03-16-2009, 05:58 PM

not sure if it will help or not but this mount appears to have the gussets.http://www.vansairforce.com/communit...ad.php?t=28400

JoeBlank · #7 03-19-2009, 09:53 AM

Greg,

Sent you a PM.....