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 5950-01-597-6137
NSN 5985-01-501-8526
NSN 6145-00-437-0025
NSN 5935-01-507-0084
NSN 5999-00-001-2607
NSN 5835-01-632-6627
NSN 5910-01-475-5478
NSN 5910-01-299-0816
NSN 5895-01-421-1767
NSN 5945-01-302-3300
NSN 6150-01-611-1210
NSN 5910-00-864-0723