ACS Landing Gear & Brake Systems 2 — Questions and Answers
Question 1: Nose wheel shimmy on an aircraft is most commonly caused by:
- Overinflated nose gear tires
- Worn or defective shimmy damper, loose torque links, or improper tire balance (Correct answer)
- Incorrect toe-in alignment
- High-speed crosswind landings only
Correct answer: Worn or defective shimmy damper, loose torque links, or improper tire balance
Nose wheel shimmy is most commonly caused by a defective or depleted shimmy damper, loose torque link bearings, or an out-of-balance tire/wheel assembly.
Question 2: When bleeding aircraft brakes, the correct procedure is to bleed from:
- The master cylinder downward to the wheel cylinders
- The wheel cylinder bleeder valve upward to the master cylinder reservoir (Correct answer)
- Either direction, as long as all air is removed
- The highest point in the system only
Correct answer: The wheel cylinder bleeder valve upward to the master cylinder reservoir
Aircraft brakes are bled from the bottom (wheel cylinder bleeder) upward so that air bubbles, being lighter than fluid, travel upward and out through the reservoir.
Question 3: What does a landing gear squat switch (weight-on-wheels switch) do?
- Arms the gear retraction system when airborne
- Prevents gear retraction on the ground and enables ground-only functions (Correct answer)
- Activates the landing lights on touchdown
- Controls nosewheel steering authority
Correct answer: Prevents gear retraction on the ground and enables ground-only functions
The squat switch prevents inadvertent gear retraction while the aircraft is on the ground and may also enable ground spoilers, thrust reversers, or other ground-only systems.
Question 4: The correct nitrogen pressure for servicing an aircraft oleo strut is found in the:
- FAR Part 91
- Aircraft Maintenance Manual for the specific aircraft (Correct answer)
- AC 43.13-1B Table 1
- Tire manufacturer's data plate
Correct answer: Aircraft Maintenance Manual for the specific aircraft
Nitrogen servicing pressure for an oleo strut is specified in the Aircraft Maintenance Manual and varies by aircraft type, strut position, and aircraft gross weight.
Question 5: What is the purpose of wheel well doors on a retractable landing gear aircraft?
- To reduce aerodynamic drag by closing the gear cavity when retracted (Correct answer)
- To prevent ice accumulation on the gear mechanism
- To provide access for in-flight inspection
- To direct cooling air to the brake assembly
Correct answer: To reduce aerodynamic drag by closing the gear cavity when retracted
Wheel well doors close over the landing gear bay after retraction to create a smooth aerodynamic surface and reduce drag.
Question 6: Which condition requires immediate replacement of a landing gear actuating cylinder?
- Minor corrosion on the exterior barrel
- Internal bypass causing the gear to drift from locked position under load (Correct answer)
- Slight discoloration of the cylinder finish
- Accumulation of dust around the rod seal
Correct answer: Internal bypass causing the gear to drift from locked position under load
Internal bypass (fluid passing the piston seals) causes the actuator to drift from its locked position under load, which is a safety-critical failure requiring immediate replacement.
ACS Landing Gear & Brake Systems 2
Nose wheel shimmy on an aircraft is most commonly caused by: