[QUOTEI do not know about the props for radial engines. For Allison engines however... In the following P-38 training film, the pilots are told to rev the engines prior to take off to make sure that the propeller governors work. If one fails the engine "runs wild".
That advice is at about 7 minutes into the film.
][/QUOTE]
As far as I know, this was SOP for all constant prop engines. When doing the run up to check mags, the pilot would "exercise" the props, pulling the prop lever through its range, to "loosen up" the mechanism, making sure the oil is flowing and everything is working.
The P38's had Curtass electric props, no oil, but still mechanical/electric parts to fail. I have read many P38's sent to England had a problem with runaway props, traced back to corrosion in the prop control switches?