Used on v-22 lrip 1 e-nsn isil. 3b thread class 32 thread quantity per inch nut, self-locking, castellated, hexagon counterbored, assembled washer, 250 deg f, non-metallic insert ( for self-retaining bolts) MS21224 has been replaced by NASM21224 dated NOVEMBER1999
Used on v22 aircraft. 3b thread class 24 thread quantity per inch nut, self-locking, castellated, hexagon counterbored, assembled washer, 2 50 deg f, non-metallic insert (for self-retaining bolts) MS21224 has been replaced by NASM21224 dated NOVEMBER1999