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 5925-01-230-6513
NSN 5960-01-285-2152
NSN 6610-00-437-5681
NSN 6620-00-635-7347
NSN 5945-01-383-9453
NSN 5855-01-020-3777
NSN 6145-01-386-3976
NSN 5925-00-806-7493
NSN 6130-01-534-0572
NSN 5998-01-172-6237
NSN 4140-01-529-6811
NSN 2925-00-419-5868