The item is a flight safety critical aircraft part (fscap)
A nut having 6 flat sides and an integral washer which extends beyond the flats or periphery. An integral feature is incorporated for locking on the threads of a mating member.
Classification: Nuts of iron or steel
NSN 5965-01-429-9777
NSN 5925-00-636-5683
NSN 2925-01-255-4875
NSN 6645-01-128-6932
NSN 5930-01-474-2698
NSN 5910-01-317-3865
NSN 5999-00-579-9513
NSN 6135-01-204-3882
NSN 6145-01-501-6548
NSN 5985-00-189-7138
NSN 5930-00-905-2551
NSN 6620-00-585-5443