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 5998-01-071-9113
NSN 5895-01-183-5333
NSN 5965-00-303-9701
NSN 6145-00-811-0986
NSN 6150-01-487-4920
NSN 5920-01-157-9471
NSN 6645-00-988-4427
NSN 5855-00-320-4116
NSN 5855-01-457-3608
NSN 5855-01-417-3250
NSN 5990-01-353-3691
NSN 5990-00-321-8459