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Engine Mounts

Chuckne

Active Member
Owner of 2002 RV 9a (bought not built)… when I purchased two years ago it had a significant droop of the engine. Spinner was 3/4” below cowling. I have multiple photographs when the plane was first completed and there was no droop. I installed new berry mounts this summer and not much change. Added a second washer between the bottom mount and the engine…the spinner now sits a half inch below the cowl. Engine mount and firewall don’t have any obvious damage or bent parts. Looking for any thoughts, input or magic as to what could have changed. Are there alternative mounts that are thicker/thinner that could have changed the orientation of the engine to the cowl. Thanks in advance.
 
Are you sure the Berry mounts are oriented correctly? I'm not sure about the RV9A but on my RV8 the plans called for the top and bottom mounts to be oriented opposite of each other.
 
Yes they are oriented correctly. Hard durometer against the lower case and top towards firewall. Thus hard side in compression. With as far off as the cowl is…I almost wonder if they were put in wrong when the cowl was fit as the hard side is not as thick in height as the soft side.
 
I have experienced drooping in the area of 3/16, maybe 1/4" over time and use. The amount of droop seems to vary a bit, but I would never expect an engine to droop 3/4". The fact that new mounts brought it back to 1/2" is somewhat in line with normal behavior. I suspect the plane when new had a 1/2" droop and was due to builder error with the initial cowl installation. Not sure shimming will fix it, as it could create an angle problem between the cowl and spinner.

Larry
 
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That does sound a bit excessive. I just passed 900 hours on my airplane and I've accumulated about 5/16" of engine sag on the mounts, enough that I will put a washer on the bottom mounts this spring during annual to level it.
 
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