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 6620-01-659-1256
NSN 5950-01-469-8054
NSN 6320-00-937-5625
NSN 5985-01-309-9268
NSN 5965-01-577-8503
NSN 6135-00-377-9165
NSN 6240-01-176-2409
NSN 5935-01-590-6752
NSN 5990-01-236-8399
NSN 6320-00-343-1798
NSN 5920-00-529-0618
NSN 5975-01-307-1716