900 Series AN Flat Washers (Air Force-Navy Aeronautical Standard)

What are 900 series AN washers used for?

AN washers in the 900 series, most commonly the AN960, do three jobs in aircraft hardware: they give a smooth bearing surface under a hex or castle nut, they act as shims to obtain the correct grip length on a bolt and nut assembly, and they adjust the position of castle nuts so the cotter pin holes line up. AN960 comes in a regular thickness and a thinner "L" light variant for fine grip adjustment. Made from 18-8 stainless, these washers resist corrosion for airframe and outdoor exposure. Where a drawing calls for a 900 series AN part number, use the certified AN washer rather than a commercial equivalent.

Why choose 900 series AN flat washers

• Aeronautical standard: manufactured to 900-series Air Force-Navy AN specifications.
• Grip adjustment: used as shims and to set castle nut position.
• Corrosion resistant: 18-8 stainless resists rust and oxidation.
• Certified: called out by AN part number for conformance.

Common applications for 900 series AN flat washers

• Aircraft and airframe assemblies
• Shimming for correct bolt grip length
• Castle nut and cotter pin alignment
• Any drawing specifying a 900 series AN part number

For related standards, see NAS aerospace flat washers and 800 series MS military standard flat washers, and browse every option on the main flat washers category.

900 Series AN Flat Washers FAQ

What does AN stand for?

Air Force-Navy Aeronautical Standard, a family of standards for aircraft hardware. AN960, in the 900 series, is the most widely used AN flat washer.

What is the difference between AN960 and AN960L?

AN960 is the standard thickness. AN960L is a lighter, thinner version, roughly half the thickness, used for fine grip-length and castle nut adjustment.

What are 900 series AN washers used for?

A smooth bearing surface under nuts, shims to set correct bolt grip length, and adjusting castle nut position so cotter pin holes align.