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 4140-00-023-5949
NSN 6685-01-267-0616
NSN 5990-01-226-2653
NSN 2925-01-394-5650
NSN 6110-00-663-4054
NSN 5990-01-334-8634
NSN 6650-00-963-1692
NSN 5925-01-449-2188
NSN 5985-01-079-2859
NSN 5999-00-801-3394
NSN 2925-00-432-3410
NSN 6135-01-659-3426