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 5960-01-261-5143
NSN 5920-01-410-7343
NSN 5895-01-346-0739
NSN 6240-01-463-3132
NSN 5920-00-470-2903
NSN 6645-01-363-9028
NSN 5999-00-006-3170
NSN 5855-01-020-7982
NSN 5835-01-408-7576
NSN 5965-00-201-7479
NSN 6130-01-316-4279
NSN 5999-01-213-9292