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 5920-01-305-7258
NSN 6685-01-306-1218
NSN 7035-00-155-9513
NSN 6130-01-515-4100
NSN 5996-00-999-8692
NSN 6220-01-230-0872
NSN 5920-01-162-0750
NSN 5950-01-502-8219
NSN 5945-00-499-7237
NSN 5998-00-275-2145
NSN 5930-01-198-8864
NSN 5910-01-556-8008