Cracked engine mount

[sdemeyer]

While preparing for installation of new motor mounts, I couldn't help but notice some cracked powder coating. Further investigation revealed a crack going 80% around the engine mount tube.

What is a standard repair procedure for this?

Thanks, Scott

[akarmy]

What is a standard repair procedure for this

Well, the only solution is to remove the mount and get it welded, then repaint. Here's a set of pictures of the process on an RV mount. It would be best to follow the same procedure.

http://www.vansairforce.net/_WWWTP/3.htm

[Av8r3400]

Motor mount cracking has been a problem with the 912 on these planes. Kitfox does have a replacement mount that is gusseted and stronger, now.

Maybe worth a look?

[SWeidemann]

I recently bought a Kitfox Vixen with the pretty high time 912 ULS (1600 hours +). It has a definite crack about 2/3 of the way around on one of the top engine mount tubes. I have a new powder coated engine mount standing by for replacement (bought new from the McBean's Kitfox). I'm wondering if the old mount will be salvagable or is it wall decor? Also, does anyone have advice on whether to replace the engine mount isolator rubbers now or can they be returned to service?

Skot
Kitfox 5 Tri Gear, 912 ULS
N24V


Motor mount cracking has been a problem with the 912 on these planes. Kitfox does have a replacement mount that is gusseted and stronger, now.

Maybe worth a look?

[SkyPirate]

Most cracks can be fixed, and either gusseted or capped with 4130 but always on a cap bring it to a point and back weld over the points once its 100% welded, the cap brought to a point still allows for minimal flex but it also distributes the stress more evenly across the patch <> and the reason for back welding at the points, if its going to crack again it will most likely crack at the " dimple" of the last weld, so always back weld to fill the dimple

[n85ae]

That mount looks like it was Mig welded, which is typical on Kitfoxes. Looking
at where it cracked it looks like it may have been embrittled by the mig welding
process. That's my guess anyway, I'd get it rewelded, and keep checking
often. I wish they didn't use mig, I've never been happy with it on my plane,
although I've never had any breaks so far ...

Regards,
Jeff

[Slyfox]

back in the old days when I had the ul engine and the older mount, I would get a crack and I would take my line feed out to the airport. grind off the area and weld it right on the airplane. worked for me. now I have the uls and the new mount, no more issues, thicker tubing.