FAA Commercial Pilot Airplane (CAX)Aircraft SystemsMedium
Some retractable-gear airplanes incorporate a mechanical pin or lock on the landing gear control lever that must be manually released before the lever can be moved to the 'up' position. What is the purpose of this device?
- ATo prevent gear extension above the maximum landing gear operating speed
- BTo indicate that the landing gear doors have closed and sealed properly
- CTo provide a mechanical backup preventing inadvertent gear retraction while the airplane is on the ground
- DTo allow manual gear extension in case of a hydraulic system failure
Show answer & explanationAnswer & explanation
Correct answer: C. To provide a mechanical backup preventing inadvertent gear retraction while the airplane is on the ground
The mechanical downlock pin on the gear control lever provides a physical backup to the squat (weight-on-wheels) switch, preventing an inadvertent gear-up selection while the airplane is on the ground. It is not related to emergency extension, door indication, or airspeed limitations.
Why the other options are wrong
- A. Gear operating speed limits are procedural/airspeed-based, not enforced by this lever lock.
- B. Gear door position is shown by cockpit indicators, not this lever lock.
- D. Emergency manual extension uses a separate system (often a free-fall handle or pump).
Gear Lever Downlock Pin
A mechanical pin/lock on the landing gear control lever that must be released before the lever can be moved up, backing up the squat switch against inadvertent ground retraction.
- Mechanical backup to the electrical squat switch
- Must be manually released to select gear up
- Prevents accidental gear retraction while airplane is on the ground
Memory trick: Pin locks the lever so ground crews can't accidentally fold the legs.