The Cessna 120-140 Association Forum

Would any members please share a photo of their safety wiring for wing fuel sumps? The anchoring hole is punched far enough away to confuse me about how to wire this with some tension but also without damaging the aluminum. 0.020 metalized wings in my case. Seems fabric makes this even more tricky?

F-5N from today for your enjoyment.

You don't really need any tension. An IA I once worked with told me safety wire is there to keep the fastener/part from falling off. If it unscrews 1/6 of a turn it won't cause a catastrophic failure.

If the tank has a tapered thread for the valve then it originally didn't come with any safety wire.

Thank you John, as always

Never wired from when I bought this airplane. Makes me wonder if they are tapered thread. Im certainly not going to pull them out just to check.

Look at it from the side, between the wrench flats and the tank. If you see threads, it's tapered thread. If you see a gasket or o-ring or there's no gap, it's not. I recall the tapered thread valves are not drilled for safety wire, so, if it's drilled it probably should (read "must") be safetied.

No gap - mystery solved. Safety wire it is!

Thank you John

FWIW mine is wired to an area washer with a peripheral hole under one of the wing root fairing screws.