MS21224C, MILITARY STANDARD: NUT, SELF-LOCKING, CASTELLATED, HEXAGON, COUNTERBORED, ASSEMBLED WASHER, 250 DEG. F, NON-METALLIC INSERT (FOR SELF-RETAINING BOLTS) (30 NOV 1988) [SUPERSEDED BY NASM21224]

MS21224C, MILITARY STANDARD: NUT, SELF-LOCKING, CASTELLATED, HEXAGON, COUNTERBORED, ASSEMBLED WASHER, 250 DEG. F, NON-METALLIC INSERT (FOR SELF-RETAINING BOLTS) (30 NOV 1988) [SUPERSEDED BY NASM21224].