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 6620-00-470-3219
NSN 5999-01-540-5257
NSN 7035-00-270-5519
NSN 5996-01-054-4954
NSN 5985-01-173-0974
NSN 5835-00-289-9080
NSN 6145-00-801-4621
NSN 4140-01-512-0744
NSN 5950-01-106-2417
NSN 5920-01-118-9492
NSN 5960-01-219-5504
NSN 5910-00-456-9511