FAA Commercial Pilot Airplane (CAX)Aircraft SystemsMedium
During a preflight briefing, a pilot reviews the emergency landing gear extension procedure for a retractable-gear airplane equipped with a hydraulic gear system. Which method is most commonly used to lower the gear if primary hydraulic power fails?
- AIncreasing engine RPM to boost hydraulic pump output
- BActivating the autopilot's altitude hold function to trigger extension automatically
- CA manual release that allows the gear to free-fall and lock into position, assisted by gravity and airflow
- DReversing electrical polarity to the gear motor
Show answer & explanationAnswer & explanation
Correct answer: C. A manual release that allows the gear to free-fall and lock into position, assisted by gravity and airflow
Most hydraulic retractable-gear systems include an emergency mechanical release that disconnects the gear from the hydraulic system, allowing it to free-fall (or be assisted by a hand pump) into the down-and-locked position using gravity and airflow.
Why the other options are wrong
- A. Engine RPM changes do not restore a failed hydraulic system.
- B. Autopilot systems have no function related to landing gear extension.
- D. Reversing polarity applies to some electrically actuated gear systems, not hydraulic free-fall systems.
Emergency Gear Extension
A backup method, typically a mechanical release or hand pump, that allows the landing gear to free-fall and lock down if the primary hydraulic system fails.
- Mechanical release disconnects hydraulic lock
- Gravity and airflow help gear extend
- Some systems use a hand pump to build backup pressure
Memory trick: When hydraulics quit, gravity does the work.