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 5975-00-822-2889
NSN 6220-01-634-0660
NSN 6220-01-237-2488
NSN 5998-01-476-0592
NSN 5990-01-458-6411
NSN 5945-00-838-2443
NSN 5905-01-046-3458
NSN 6620-01-621-0719
NSN 6650-01-376-1692
NSN 6645-00-451-6462
NSN 6110-00-075-5660
NSN 7035-01-460-2261