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 6135-00-009-4100
NSN 4140-01-139-4877
NSN 5950-01-583-8433
NSN 5998-01-157-8824
NSN 5925-00-557-4530
NSN 5920-00-893-4985
NSN 6220-00-248-4483
NSN 5930-00-783-8924
NSN 5895-01-612-3647
NSN 5996-00-337-5158
NSN 5895-00-924-0876
NSN 6150-00-212-3975