Cracking on rear engine cowling.....

[Roger]

Just a shot in the dark here, but how are your rear motor mounts? If they are getting worn it is possible that your rear exhaust pipes are vibrating against the cowl where they exit, and or just excess vibration.

[edasmus]

Thanks Roger,

Several of the engine mounts have been replaced over the years. In fact I have one on the front that will be replaced this annual. The cracks keep occurring on the lower "ring" portion of the cowling underneath the prop spinner. It has been repaired several times but the underlying issue seems to be that the entire assembly cannot be reassembled after the repair without having that piece under some stress. The repairs last about 100 hours and then the cracks reappear. The entire cowling has many patches on it so my IA's thought is to attempt to just replace the entire two assemblies hopefully from the same airplane.

We'll see!

Ed

[edasmus]

Roger,

I'm assuming you have not had this issue with your airplane??? I believe our airplanes are identical back there.

Ed

[Roger]

Yes my motor mounts were soft and it allowed the engine to drop enough that the exhausts had actually slightly deformed the bottom of the holes where they exit the cowl. I didn't have any cracks but I did have a bunch of loose rivets which I think were caused by the issue

[edasmus]

Interesting. I have not experienced that sort of issue with my airplane.

[Roger]

Also as I think back about 15 years ago I hare a 70 skymaster that had a screen on the top half and disc on the bottom and the bottom kept cracking. My 80 h doesn't have the screen on top and I haven't had the cracks, just the vibrated out rivets.

[edasmus]

No screen on my 73 G either. I'm searching as we speak for the two assemblies. Sending emails to every salvage yard Ernie has listed on his web-site. Hopefully I get lucky. The thought of wasting more time and money trying to repair my existing one again does not sound too appealing.