O ring?

[AOP]

I recently changed the oil in my C-90-12F and yesterday when I went to fly, I noticed a broken O ring laying on the floor under the nose. It's 1 1/8" diameter, reasonably thin. I can't think of what it could be. Does anybody have any ideas?

I know it's probably something obvious, but nothing comes to mind.

 

[huston marlowe]

 

[AOP]

 

[huston marlowe]

 

[Fifinella]

 

[cubdriver2]

 

[AOP]