Posted at the request of barit1. The graph explaining why the props rotate in the direction they do.
As an aside, it may be of interest that most, but not all, P-38s only had one generator, that being mounted on the left engine. Remembering that the props were electrically operated, the CSU had to be turned off (to conserve the battery), so that you were then left with a fixed pitch prop.
The FAA defines "Critical engine" as " the engine whose failure would most adversely affect the performance or handling qualities of an aircraft." I guess the left engine could be deemed to be the critical engine, if one were to nit pick, on the 38 on that basis.