The International Cessna^® 170 Association

Just changed oil for first time on my plane. Did a search here and got good info, and things went smoothly. Question though, I noticed that I have a 1" nut in front of the big square nut which holds oil screen with the AN900-28 copper crush washer. The 1" nut also had a copper crushwasher on it, but much smaller. Anyone know offhand the size of this washer? Should I change it at every oil change also?

It's an AN900-10. I change it if that nut turns on the oil screen. Sometimes get thru the oil change without that one turning and don't have to replace the crush gasket. As a side note, SNAP-ON tools has a thin open end wrench that works really well on the oil screen.

Tom- Thanks for the info. I'll check out Snap-On tools.