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 6135-00-170-8819
NSN 6135-00-405-1989
NSN 5930-01-289-2118
NSN 6685-00-469-0474
NSN 5985-00-808-3051
NSN 5930-01-605-5449
NSN 6110-00-218-0967
NSN 6150-00-247-4733
NSN 7035-00-631-3782
NSN 6620-01-025-3401
NSN 5920-01-087-6073
NSN 5920-01-172-8509