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 7035-01-435-4009
NSN 5920-01-351-7936
NSN 5960-01-624-1170
NSN 6150-01-631-7604
NSN 6135-01-574-6185
NSN 5855-01-331-7482
NSN 5998-00-400-8386
NSN 6110-00-133-2429
NSN 6240-01-055-5193
NSN 6130-01-168-8001
NSN 6645-00-089-8842
NSN 5990-01-236-8399