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 5895-01-123-9669
NSN 5935-00-867-5667
NSN 2925-01-534-5389
NSN 6145-01-617-5789
NSN 6150-00-335-7189
NSN 6130-00-886-9480
NSN 6645-00-023-8386
NSN 6610-00-725-3906
NSN 6135-00-284-1406
NSN 6320-01-415-0953
NSN 5920-01-623-1726
NSN 5925-00-175-9349