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 2925-01-261-0701
NSN 5905-01-616-0549
NSN 6220-01-098-1808
NSN 5945-01-339-5903
NSN 6110-01-454-2595
NSN 5965-01-364-7275
NSN 5910-01-631-4467
NSN 6145-01-534-7170
NSN 6145-00-284-1495
NSN 5915-00-677-0950
NSN 5998-01-520-3922
NSN 5855-01-451-1163