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 6650-01-432-5461
NSN 6620-00-713-2701
NSN 2925-00-749-8893
NSN 6620-01-254-3609
NSN 5950-01-583-9877
NSN 5990-00-903-8672
NSN 6135-00-422-3967
NSN 5915-01-196-6016
NSN 6620-00-017-8098
NSN 5950-01-091-3191
NSN 6130-01-067-9383
NSN 5920-00-035-4846