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 6130-01-057-5586
NSN 5930-01-414-2620
NSN 6110-00-061-9239
NSN 5920-00-835-6013
NSN 5960-00-736-8568
NSN 5905-01-106-6143
NSN 5985-00-636-8689
NSN 5920-01-378-5470
NSN 6685-01-568-9814
NSN 6130-01-436-3611
NSN 6150-01-351-9618
NSN 4140-01-624-3989