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 5999-01-035-9817
NSN 5910-01-556-0538
NSN 5945-01-453-9675
NSN 5925-00-144-0482
NSN 5998-00-957-1795
NSN 5985-01-061-8828
NSN 6240-01-437-9313
NSN 6105-00-626-0205
NSN 6135-01-226-4071
NSN 6650-01-568-0299
NSN 5985-00-901-3895
NSN 6645-00-514-4017