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 6620-00-578-5851
NSN 5975-00-189-0857
NSN 5905-01-119-3584
NSN 2925-00-928-5931
NSN 5835-00-280-8494
NSN 6320-01-450-7513
NSN 6135-01-519-7879
NSN 5960-01-441-7047
NSN 5960-01-190-2996
NSN 5835-00-953-0962
NSN 6145-00-480-6194
NSN 5920-01-625-5734