Addressing Engine Sag

[lr172]

I left my Spinner about an 1/8" higher than the centered position on the cowl. After 150 hours, I am now about an 1/8" lower than the centered position. It is enough that I am getting bugs deposited on the upper radius of the cowl at the spinner interface, so getting a small drag penalty. I also notice that the clearance between the cowl and spinner has shrunk on the bottom, indicating that it is tipping downward/forward and not just straight down.

I am wondering what the best or recommended fix is. It would seem that adding a large washer under the lower rubber mounts would be best, but could also add washers at the lower engine / firewall mounts. I just don't know if that creates any structural issues. If I put washers under the rubber mounts, can I get away with slots in them to ease the installation?

How have others successfully addressed this issue?

Thanks for your input.

Larry

[Carl Froehlich]

That is a lot of sag for such few hours. I did about the same bias up on my first RV and at 900 hours the engine is still in the same place.

Two things:
- consider new mounts.
- if you do put in washers on the bottom it is not that hard to just lift the engine and get the washers in after you pull the bolts, so don't slot the washers.

Carl

[Auburntsts]

Originally Posted by lr172

I left my Spinner about an 1/8" higher than the centered position on the cowl. After 150 hours, I am now about an 1/8" lower than the centered position. It is enough that I am getting bugs deposited on the upper radius of the cowl at the spinner interface, so getting a small drag penalty. I also notice that the clearance between the cowl and spinner has shrunk on the bottom, indicating that it is tipping downward/forward and not just straight down.

I am wondering what the best or recommended fix is. It would seem that adding a large washer under the lower rubber mounts would be best, but could also add washers at the lower engine / firewall mounts. I just don't know if that creates any structural issues. If I put washers under the rubber mounts, can I get away with slots in them to ease the installation?

How have others successfully addressed this issue?

Thanks for your input.

Larry

I added a washer (no slots) to to the lower rubber mounts, but that was for an RV10 as that's the easiest, and really only practical solution due to how the 10's engine mount attaches to the firewall. YMMV on a 6........

[noelf]

I see you have a -6A. If you put washers between the 4 lower engine mount points and the firewall, you will also change the geometry of the nose gear leg-to-nose gear intersection fairing that is attached to the bottom of the lower cowling. Just something to consider.