The International Cessna^® 170 Association

I bought a structural stainless screw kit for my wing tank covers ( from D&D ) Thought this would be a great idea after all the trouble I had getting the old ones out.
Should I be using plastic washers to prevent corrosion or might I be OK.

Any ideas/comments ??

thanks.............................Jim

If you have a marine supply place near you. Get some Mercrusier anti- corrosion grease and apply to the threads of any bolt and you will be able to remove them years down the road. I use it for boat, auto, small engine, and aircraft saves a lot of grief next time.

I use plastic washers under all the exterior screws on my 170. I'm not so worried about corrosion, although that can be a factor. What I want is something to keep the heads from tearing up the aluminum when the cowling and inspection plates are removed and replaced.
As was once said, 'we wear out our airplanes more taking them apart and putting the together every year than we do flying them!'
Sturgis Aviation, that painted my 170, uses plastic washers under all the exterior screws to protect the paint. Good enough for me!

I use thin plastic washers under exterior screws for two important reasons: to protect the paint AND these washers seem to help keep the screws from loosening up. I believe the washers compress just enough so that the screw head seats very slightly in the plastic, and the plastic slightly "sticks" to the surface, but not enough to damage paint.

I like the nylon washers also but I have wondered if there are places they should not be used. I have seen these washers split, especially after repeated use, which would automatically loosen the screw. Some screws are considered structural and some aren't but I'm no expert.

Yes, I believe you are correct--plastic washers are not intended for use with structural bolts. I've been told stainless steel doesn't have the strength to be deemed a structural fastener. Structural fasteners are alloy steel or better. That's why I understand you shouldn't substitute a stainless fastener for an alloy steel one, unless it's in a nonstructural application.