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 4140-01-350-3277
NSN 5950-01-068-3144
NSN 6620-01-391-7331
NSN 6105-01-423-9451
NSN 5855-01-323-5394
NSN 6135-00-474-1397
NSN 6220-00-548-1999
NSN 7035-01-179-5667
NSN 5996-01-417-7634
NSN 5930-01-422-1195
NSN 6645-00-116-1409
NSN 6220-01-505-3356