On rotor brake equipped helicopters, operating an engine against gust lock is prohibited.

• A. Allowed
• B. Prohibited
• C. Not recommended
• D. Optional

Answer: (B)

Operating an engine against gust lock places a large, unyielding load on the drivetrain. Gust locks are there to prevent rotor movement from gusts when the helicopter is parked, not to absorb engine torque. When power is applied, the engine tries to turn the rotor, but the gust lock holds it in place, causing excessive stress on the lock mechanism, rotor head, driveshafts, and the gear train. That overloading can damage the gust lock, gearbox, or other components, and can lead to costly repairs or a safety hazard if the lock gives way. For rotor brake equipped helicopters, the safe procedure is to avoid applying power with the gust lock engaged altogether, so the engine isn’t fighting a locked rotor. The other options would imply some degree of permission or practicality, which isn’t acceptable given the risk of damage and a potential safety incident.