AN Standards question...

[Cvairwerks]

Anyone have a copy of AN940, or know where one is without me having to mortgage a vehicle to get a copy? The 940 is known as a Burr Washer and was cancelled in 1960. The only other reference I've found says use an AN960 as replacement. I need to see the actual dimensions chart to see if that's a valid call for some locations on the Fairchild, or if I should be using AN970's instead.

[lucky52]

I'm not sure if this will help or even if it what you are looking for, but my 1952/1958 copy of the Standard Aircraft Handbook lists the AC 940 WASHER,BURR made out of tinned steel, brass, copper, aluminum, or aluminum alloy. It lists 12 different sizes. It also lists the AN970 WASHER,FLAT- FOR WOOD.

[EW439]

PM me an email address I will send it to you. By the way, fairchild used a washer on wood parts that was smaller than a AN970 but bigger than a AN940. I can provide both the American print that was steel and the Fleet version was Aluminum.

[ZRX61]

https://www.univair.com/hardware/washer ... rr-washer/

[Cvairwerks]

https://www.univair.com/hardware/washers/an940-burr-washers/an940-8-burr-washer/

Knew about them having the two sizes. I needed a full copy of the spec to find the data that they omitted from the catalog....actual diameter, hole diameter, material and thickness, all of which are non standard compared to other washers.

In the case of the -4, it's actually an AN940-416, made of tinned steel, has an OD of .625", an ID of .265" and a thickness of .065". Add a material code and you also have pure aluminum, aluminum alloy, brass and copper versions.

It's a weird spec, in that all the dimensions are listed in fractions with the exception of the thickness, which is decimal. The spec also states that for design work after Aug 1948, to use AN960's instead. It also states that the 940's are off the shelf commercial items with all the dimensions taken directly from the United Screw and Bolt Co. catalog.

Chasing some of this stuff down leads to silently asking "Why".......