FAA Aviation Mechanic Airframe (AMA)Landing Gear SystemsHard
During a landing gear retraction functional test, a technician verifies the sequence of switch actuations. In a properly rigged system, which sequence correctly describes normal gear retraction after liftoff?
- AThe squat switch engages and holds the gear down throughout retraction
- BThe gear retracts fully before the downlocks disengage
- CSquat switch releases (weight off wheels), downlocks disengage, gear retracts, uplocks engage and the gear position light goes out
- DUplocks engage before the downlocks disengage, then the gear retracts
Show answer & explanationAnswer & explanation
Correct answer: C. Squat switch releases (weight off wheels), downlocks disengage, gear retracts, uplocks engage and the gear position light goes out
On a properly rigged system, liftoff removes weight from the squat switch, permitting the retraction sequence to begin: downlocks must disengage before the gear can retract, and once fully retracted the uplocks engage, extinguishing the gear position light. Any other order indicates improper rigging or a malfunction.
Why the other options are wrong
- A. An engaged squat switch (weight on wheels) would prevent retraction as a safety interlock.
- B. The gear cannot retract while downlocks remain engaged; they must release first.
- D. Uplocks cannot engage before downlocks release, since the gear is still extended and locked down.
Landing Gear Retraction Sequence
The proper order of switch actuation and mechanical events during gear retraction, verified during a functional/rigging check: weight off wheels, downlock release, gear retraction, and uplock engagement.
- Squat switch must sense weight-off-wheels before retraction
- Downlocks must release before gear can move
- Gear retracts into wheel well after downlock release
- Uplocks secure gear up and extinguish position light
Memory trick: Weight off, lock off, gear goes, lock on.