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 5998-01-065-3697
NSN 5935-01-413-4414
NSN 5910-01-142-5815
NSN 5855-00-586-6255
NSN 5835-01-597-4820
NSN 5998-00-661-0380
NSN 6145-01-364-0346
NSN 6620-00-888-3179
NSN 5950-00-065-5221
NSN 5895-00-903-3458
NSN 5925-01-037-1629
NSN 7035-01-145-5059