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 5996-01-112-2731
NSN 7035-01-290-9770
NSN 6220-01-176-9139
NSN 5960-01-406-0299
NSN 6135-01-564-8390
NSN 5945-01-502-5961
NSN 6320-00-242-3300
NSN 6130-01-507-7918
NSN 5855-00-106-1640
NSN 5925-01-385-4605
NSN 5965-01-429-9777
NSN 5855-01-234-5346