David Levy:
How can I find the correct part number for the copper-asbestos crush gaskets (AN900?), which are used on most of the straight-thread engine plugs and oil screen holders?
Editor:
Have you obtained your toolbox hardware quick-reference book yet, from Genuine Aircraft Hardware? Free with any hardware order, though they
do have a minimum order. This book will tell you at least 90% of everything
you need to know about aircraft hardware. Page 98 shows the reference for
MS35769 crush gaskets; the MS35769 specification supersedes the old AN900 specification. The reference includes the cross-reference from the AN900 number to the new MS35769 number.
All you need to know, to select a gasket size, is the inner diameter of the gasket. You can measure the ID of the old one, or you can measure the OD of the part it is being used on (like a plug or screen holder).
If you don’t need to place a minimum order with GAH, Aircraft Spruce still lists the gaskets under their AN900 number, and shows the ID so you can select the correct one. Note that the dash numbers are not the same, for a given size. For example, an AN900-16 crosses to an MS35769-21.