Cracking on rear engine cowling.....

edasmus · #1 01-10-12, 06:53 PM

Hey Ernie (or anyone else),

Do you ever have any issues with cracks on your rear engine cowling of your 73 G model? I have been battling this ever since I purchased the airplane almost 10 years ago. Countless repairs have not held up and my IA thinks it's time to find an entire replacement assembly of the upper and lower.

1552200-200 Upper Tail Cap Assembly

1552123-9 Lower Tail Cap Assembly

The names are slightly misleading. These are the top and bottom of the engine cowl for the rear engine. See page 188 in the parts catalog, Figure 72 for the diagram. I need item number 26 (lower) as seen in the diagram and item number 36 (upper) as seen in the diagram.

I am on the hunt but curious if you have had any of these issues.

Thanks,

Ed

Roger · #2 01-10-12, 07:46 PM

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 · #3 01-10-12, 08:00 PM

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 · #4 01-10-12, 08:02 PM

Roger,

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

Ed

Roger · #5 01-10-12, 08:09 PM

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 · #6 01-10-12, 08:10 PM

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