The answer/solution is worse than the original problem. Manual actuation gives you "Feel" so the linkage doesn't get destroyed by something getting misaligned etc. The controls on a DC-9 are manual by servo tabs. Ona DC 4 they are just manual Max wt 72,000 Lbs. You are talking about a single cowl flap on a very LIGHT plane. Introducing risks where none needs to be. Weight Costs Complexity and unreliability. BAD design and design philosophy. Nev