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 5835-01-602-0311
NSN 6145-01-397-6210
NSN 5915-01-531-8726
NSN 5915-01-578-3343
NSN 6135-01-396-4900
NSN 5945-01-598-8388
NSN 4140-00-001-1536
NSN 5996-01-549-6387
NSN 5950-01-417-1500
NSN 5990-01-425-2175
NSN 6105-01-489-5498
NSN 5920-01-475-7715