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 6650-01-455-6028
NSN 6320-01-090-8296
NSN 2925-01-424-0235
NSN 6145-01-152-5083
NSN 6220-01-065-8544
NSN 6645-01-296-0882
NSN 5915-01-329-3669
NSN 6145-00-482-1724
NSN 6150-00-549-2427
NSN 5930-01-171-9166
NSN 5920-01-378-3869
NSN 6105-01-446-6527