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 5945-00-673-3964
NSN 6610-01-254-4196
NSN 6240-01-303-3171
NSN 6220-00-364-1605
NSN 5855-00-151-3853
NSN 5999-01-207-1263
NSN 6220-00-920-8225
NSN 5930-01-596-4596
NSN 6650-01-633-9147
NSN 5996-01-127-5431
NSN 4140-00-504-1829
NSN 5910-01-486-9478