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 5920-01-027-0660
NSN 5965-01-560-8572
NSN 5965-01-605-1753
NSN 6110-01-472-1963
NSN 5975-00-703-5237
NSN 6135-00-351-8606
NSN 6645-00-300-0401
NSN 6610-01-112-8137
NSN 6685-00-194-9803
NSN 6135-00-563-7711
NSN 6650-01-571-9386
NSN 5835-00-393-1996