If an aircraft lacks negative torque sensing, what should the propeller be in terms of configuration to affect VMCA?

• A. Feathered
• B. Full forward
• C. Full reverse
• D. Stopped

Answer: (A)

When an engine fails, VMCA is all about keeping control in the presence of the other engine’s effects on the airplane’s yaw and roll. If there’s no negative torque sensing, you can’t rely on automatic adjustments to offset the yaw caused by the windmilling prop on the failed engine. Feathering the failed engine’s propeller aligns the blades with the airstream so they produce minimal drag and negligible windmilling torque. That dramatically reduces the yaw and side-force the operating conditions would otherwise generate, making it easier to maintain control at lower speeds and thus lowering VMCA.

Leaving the prop in full forward would create substantial windmilling drag and a stronger yaw moment, making control harder. Full reverse isn’t used in normal flight for most propellers and would introduce handling complexities. Keeping the prop stopped isn’t a practical or reliable way to achieve controllability in this scenario, whereas feathering provides the needed reduction in drag while the engine is still inoperative.