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 5965-01-619-5520
NSN 5935-00-952-8642
NSN 7035-00-483-8630
NSN 5915-01-633-9845
NSN 5895-00-476-0515
NSN 4140-00-045-8117
NSN 6650-01-380-1394
NSN 5960-01-141-7584
NSN 6105-01-487-7484
NSN 5855-01-538-3743
NSN 5960-01-328-8248
NSN 6150-01-380-2223