Green’s Dictionary of Slang

(orig. RAF) a mechanic.

1918		K. MacLeish letter 22 Feb. in Rossano Price of Honor (1991) 104: The C.O. got fed up on this and sent an American mech out.
1919		in Columbia Press Yank Talk 17: The ‘mech’ expired without a sound.
1931		Post & Gatty Around World 57: His ‘mech’ was giving the Bellanca its last testing.
1943		W. Simmons Joe Foss Flying Marine 47: We watched ‘mechs’ start the planes, check magnetos, props, engine, and tabs.
1950		Popular Science May 142: Senior mech Harry Baker said, ‘Imagine a mechanic that’s never on his back.’ [HDAS].
1953		W. Harrison Army Girl (1962) 13: Is it true the motor machs gave a mosquito a complete overhaul over there before they realized it wasn’t a B-36?
1962		S. Smith Escape from Hell 68: The motor mechs did a job on ’em [HDAS].