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 6685-01-556-3449
NSN 5910-00-751-9581
NSN 5950-01-029-3613
NSN 5905-00-513-9946
NSN 5920-01-652-1179
NSN 5996-00-653-4280
NSN 6145-00-674-1807
NSN 6220-01-189-6147
NSN 5975-01-346-9696
NSN 5985-01-234-2342
NSN 5985-01-510-2573
NSN 6645-00-117-9839