Men attending to a large propeller on an aircraft assembly line, ca.1940

Photograph of a man by a large propeller on an aircraft assembly line, ca.1940. A man stands on a wooden ladder, and works right of a large propeller. Beneath him, another person dressed in light sanitation gear stands with tools in hand. Part of the wing(?) of the plane can be seen in the foreground, at right. The windows of the opposite side of the factory wall can be seen at left. Photoprint reads: "Horsepower on wings! Installing one of twin motors on a huge plane being built for national defense in a factory near Los Angeles. Probably North American B-25".