FAA Aviation Mechanic Airframe (AMA)Airframe Electrical and InstrumentsHard
A technician is troubleshooting the landing gear system on a retractable-gear aircraft. The system is designed to prevent inadvertent gear retraction while the aircraft is on the ground and to disable ground spoiler deployment while airborne. Which component provides the signal used by these interlock systems?
- AProximity sensor mounted on the wing flap
- BTorque link on the nose gear
- CSquat switch mounted on the landing gear strut
- DAnti-skid wheel speed transducer
Show answer & explanationAnswer & explanation
Correct answer: C. Squat switch mounted on the landing gear strut
The squat switch (also called a weight-on-wheels switch) senses strut compression to determine whether the aircraft is on the ground or airborne. This signal is used throughout the aircraft to inhibit systems such as gear retraction on the ground and to enable systems such as spoiler deployment only when the switch confirms ground contact.
Why the other options are wrong
- A. Flap position sensors relate to flap systems, not weight-on-wheels logic.
- B. The torque link transmits steering/torsional loads, it does not provide an electrical ground signal.
- D. Anti-skid transducers measure wheel speed for braking, not ground/air status.
Squat Switch (Weight-on-Wheels Switch)
A switch mounted on the landing gear strut that senses strut compression to signal whether the aircraft is on the ground or in the air, used for gear/spoiler interlock logic.
- Senses strut compression from aircraft weight
- Prevents gear retraction while on ground
- Enables systems like spoilers/reversers only when confirmed on ground
Memory trick: Squat down = strut compresses = switch says 'we're on the ground'