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 5990-01-320-1412
NSN 6130-01-168-7199
NSN 6110-01-415-0589
NSN 5930-00-184-7994
NSN 5990-00-288-1820
NSN 6145-00-482-1724
NSN 5895-01-269-0724
NSN 5835-00-033-0294
NSN 5915-01-336-8465
NSN 5935-01-550-3270
NSN 5920-01-412-1080
NSN 5855-01-464-5084