FAA Aviation Mechanic Airframe (AMA)Landing Gear SystemsMedium
A technician is troubleshooting a landing gear system in which the gear extends normally but the pilot reports the gear handle requires excessive force to move to the UP position after landing. Inspection reveals the mechanism that mechanically holds the gear in the extended position is not releasing properly. Which component is most likely malfunctioning?
- ASquat switch
- BSequence valve
- CDownlock mechanism
- DShimmy damper
Show answer & explanationAnswer & explanation
Correct answer: C. Downlock mechanism
A downlock mechanically secures the landing gear in the extended position to prevent inadvertent retraction on the ground or in flight; if it fails to release, the gear cannot be retracted, causing binding or excessive resistance at the gear handle.
Why the other options are wrong
- A. A squat switch senses weight-on-wheels for various systems, not gear locking.
- B. A sequence valve controls the order of gear/door actuation, not locking the gear down.
- D. A shimmy damper controls nose wheel oscillation, unrelated to gear retraction.
Downlock Mechanism
A mechanical lock that secures the landing gear in the fully extended (down) position, preventing collapse or inadvertent retraction.
- Must release before gear can retract
- Often spring-loaded or hydraulically actuated to release
- Failure to release prevents gear-up selection
Memory trick: 'Downlock locks it down until told to let go'