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 5985-00-067-7251
NSN 5960-01-488-5817
NSN 5895-00-056-8573
NSN 5915-00-162-9479
NSN 6320-00-731-6134
NSN 5920-00-755-3235
NSN 6645-00-758-0870
NSN 5960-00-672-3836
NSN 5925-01-094-3659
NSN 6105-00-655-0893
NSN 5835-01-645-2892
NSN 6650-00-207-9639