Michael,

I make a living making aerospace parts….Boeing is my largest customer….so I think my advice is sound.

4000 series steels like 4130, 4330 and 4340 are susceptible to cracking after weld if they are not preheated and post heated during the weld process.  I do not know what material your engine mount is made of but the 4000 series steels (chrome moly) are quite popular for this kind of application.  I would be very leery of welding or re-welding steel tube and not knowing what kind of steel it is.  Additionally, the quality of weld on your engine mount is not very good.  I would suggest replacing the mount unless you can confirm what material the mount was made from.  If you choose to repair the mount, Lancair should have specified the material and the fab house should have material certs from the original build.  Whether or not that information is still available….I don’t know.  Finding a good welder at an airport may be challenging.  Another thought…losing the nose gear due to mount failure would be very expensive.

Craig Berland

IV-P N7VG

<<The two attached images show a crack in the engine mount on my Lancair IV-P. #4637 shows context and #4641 details. The opposite side cracked in a similar fashion two years ago. (I have not had nose wheel shimmy.)

I would like advice on appropriate repair. My mechanic is suggesting some form of gusset which could improve the overall strength and prevent a future occurrence.

I wonder if this might not be asking for trouble. Without doing some serious engineering you could create point loads that might be worse.

Rather than remove the mount I would like to fly the plane to a highly skilled welder to make this repair. Any references for someone in the Northeast.

Other comments anyone?