FAA Commercial Pilot Airplane (CAX)Aircraft SystemsEasy
An airplane's retractable landing gear system includes a switch actuated by weight on the main gear struts. What is the primary function of this switch?
- ATo disconnect the hydraulic pump when the gear is fully extended
- BTo automatically retract the gear immediately after takeoff
- CTo prevent inadvertent gear retraction while the airplane is on the ground
- DTo illuminate the gear-down indicator only during landing flare
Show answer & explanationAnswer & explanation
Correct answer: C. To prevent inadvertent gear retraction while the airplane is on the ground
The squat (weight-on-wheels) switch senses strut compression from the airplane's weight and interrupts the gear-retraction circuit while on the ground, preventing accidental gear-up selection during ground operations.
Why the other options are wrong
- A. Hydraulic pump shutoff is typically controlled by a separate pressure or limit switch.
- B. Retraction after takeoff is still a pilot action; the switch does not automate it.
- D. The switch is not tied to indicator timing during flare.
Squat Switch (Weight-on-Wheels Switch)
A safety switch actuated by strut compression that prevents landing gear retraction while the airplane's weight is on the wheels.
- Senses strut compression
- Blocks gear-up selection on ground
- Also called a weight-on-wheels (WOW) switch
Memory trick: Squat and stay: weight on wheels keeps the gear grounded.