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 6685-01-439-9039
NSN 2925-01-146-0278
NSN 6135-00-416-2898
NSN 6145-01-249-4329
NSN 6320-01-578-6006
NSN 5975-01-314-2231
NSN 4140-01-486-6582
NSN 6650-01-608-6349
NSN 5965-00-170-5254
NSN 5920-01-596-4454
NSN 5950-01-070-0879
NSN 5925-01-268-7711