Crack in engine mount gusset

[kmach]

Hi all,

while doing my annual I found a 5/8" crack in a gusset on the engine mount of my model 5 outback.

I believe this mount is made of 4130 chrome moly, can anyone confirm this.

I think this should be weldable with out removing the mount.

Any thoughts, tips appreciated. 14175

[rv9ralph]

If the mount is powder coated, see if it will chip away from the crack. Sometimes a crack like that can just be the powder coating. If is more, the powder coating will have to be removed from the area to repair anyway.

Ralph

[PapuaPilot]

If no one is certain that it is 4130 it would be best to contact the factory. Find out what type of metal it is and have it professionally welded. It looks like you will have to remove your engine and mount from the plane. Then you need to remove the coating and have it welded. After that clean the mount up (bead blasting or similar) and prep it for primer/paint or powder coating.

Don't cut corners on an engine mount, they are too critical. If you talk to to factory ask them for advice too. Maybe this gusset isn't that critical and the crack could be stop drilled and monitored, but I wouldn't make that decision without their input.

There is also the possibility the crack could be welded without removing the engine and mount. That would depend on access for the welder and the ability to clean up the area well enough to get a coat of primer & paint on it after it is welded.

After the repairs are done it would be advisable to have a dynamic balance done to your prop; vibrations from the engine/prop are the leading cause of cracks on aircraft.