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 6150-00-055-7601
NSN 6220-00-964-1042
NSN 5960-01-207-6232
NSN 5930-01-096-4472
NSN 5960-01-263-6781
NSN 6150-01-087-8467
NSN 5975-01-050-8114
NSN 5930-01-412-6919
NSN 5975-00-081-2171
NSN 4140-00-942-4783
NSN 5935-01-124-9679
NSN 5990-00-230-8981