AMT Aircraft Landing Gear Systems 2 — Questions and Answers
Question 1: A landing gear unsafe (red) position indicator light typically means:
- Gear is fully extended and locked down
- Gear is in transit or not confirmed in a safe position (Correct answer)
- Landing gear hydraulic system pressure is critically low
- All gear doors are open and awaiting gear extension
Correct answer: Gear is in transit or not confirmed in a safe position
A red unsafe light indicates the landing gear is in an intermediate, transitional, or unlocked position — not confirmed fully up and locked or fully down and locked.
Question 2: A squat switch (weight-on-wheels switch) is used primarily to:
- Measure the aircraft's actual gross weight before departure
- Prevent landing gear retraction while the aircraft is on the ground (Correct answer)
- Activate the anti-skid system automatically during the takeoff roll
- Control nose wheel steering authority during high-speed taxi
Correct answer: Prevent landing gear retraction while the aircraft is on the ground
The squat switch senses weight on the landing gear and provides a safety interlock that prevents the gear from being retracted while the aircraft is on the ground.
Question 3: A power-boost brake system uses hydraulic power to:
- Completely replace pilot pedal input with fully automated braking
- Amplify pilot pedal input forces for more effective braking with less effort (Correct answer)
- Operate the brakes only during autoland and rollout operations
- Actuate the parking brake and emergency brake simultaneously
Correct answer: Amplify pilot pedal input forces for more effective braking with less effort
Power-boost brakes use hydraulic pressure to multiply the force the pilot applies through the brake pedals, enabling effective braking of heavy aircraft without excessive pilot effort.
Question 4: Aircraft tires are typically inflated with nitrogen rather than compressed air primarily because:
- Nitrogen provides better coefficient of friction on wet runways
- Nitrogen is dry and inert, resisting moisture accumulation and temperature-driven pressure changes (Correct answer)
- Nitrogen-inflated tires weigh significantly less than air-inflated tires
- FAA Advisory Circulars require nitrogen for all transport category aircraft
Correct answer: Nitrogen is dry and inert, resisting moisture accumulation and temperature-driven pressure changes
Nitrogen is dry (preventing moisture condensation and corrosion inside the wheel) and chemically inert, making tire pressure more stable across extreme temperature changes compared to compressed air.
Question 5: What is the function of a brake debooster valve?
- Increase hydraulic pressure to the brakes during high-speed rejected takeoffs
- Reduce high system hydraulic pressure to the lower pressure required by the brake assemblies (Correct answer)
- Prevent hydraulic fluid from entering the brake assembly during gear retraction
- Equalize brake pressure between left and right main gear automatically
Correct answer: Reduce high system hydraulic pressure to the lower pressure required by the brake assemblies
A debooster (pressure-reducing) valve steps down the aircraft's high hydraulic system pressure to the lower pressure required by brake assemblies, preventing brake component damage and overheating.
Question 6: During landing gear retraction, the typical sequence of gear door operation is:
- Gear doors remain fully open throughout the entire flight
- Doors open before gear retraction begins, then close after the gear is fully retracted (Correct answer)
- Doors close before gear retraction begins to streamline airflow
- Gear doors are operated completely independently of gear position
Correct answer: Doors open before gear retraction begins, then close after the gear is fully retracted
Sequencing valves ensure gear doors open first to clear the path for gear retraction, then the doors close behind the gear once it is fully seated in the wheel well.
Question 7: On large transport aircraft, nose wheel steering is typically accomplished by:
- Differential main wheel braking only, with no dedicated steering system
- A hydraulic actuator on the nose gear controlled by rudder pedals or a dedicated tiller (Correct answer)
- A mechanical cable system connected directly to the rudder control surface
- An electric motor driving a rack and pinion gear on the nose gear strut
Correct answer: A hydraulic actuator on the nose gear controlled by rudder pedals or a dedicated tiller
Large aircraft use a dedicated hydraulic steering actuator on the nose gear for precise ground maneuvering, controllable via rudder pedals at low angles and a nose wheel steering tiller for sharp turns.
AMT Aircraft Landing Gear Systems 2
A landing gear unsafe (red) position indicator light typically means: