Free Airframe Mechanic Aircraft Landing Gear Systems Questions and Answers

Question 1

A technician observes paint lines on an aircraft's tire and wheel rim that are no longer aligned. What is the primary purpose of these 'creep marks'?

Accepted Answer

To show if the tire has slipped on the wheel rim.

Answer

Creep marks, or slippage marks, are painted lines that extend from the wheel rim to the tire sidewall. Their purpose is to provide a visual indication of whether the tire has rotated or 'slipped' on the wheel rim. This is especially critical for tubed tires, as significant slippage can shear the valve stem off the inner tube, leading to a rapid loss of tire pressure.

Question 2

What is the primary function of a centering cam in a retractable nose landing gear system?

Accepted Answer

To align the nose wheel in the fore-and-aft direction before retraction.

Answer

A centering cam is a mechanical device within the nose gear shock strut that ensures the nose wheel is aligned straight (fore-and-aft) before it is retracted into the wheel well. As the strut extends fully after takeoff (when the aircraft's weight is off the wheels), two cams, one upper and one lower, engage to lock the wheel in the centered position, preventing damage to the aircraft structure during retraction.

Question 3

During a ground maintenance check on a retractable-gear aircraft, a technician attempts to raise the landing gear using the cockpit selector switch, but the gear does not retract. Which safety device is most likely preventing the gear retraction?

Accepted Answer

The squat switch (or weight-on-wheels switch).

Answer

A squat switch, also known as a weight-on-wheels switch, is a safety device that prevents accidental retraction of the landing gear when the aircraft is on the ground. It senses when the aircraft's weight is compressing the landing gear struts and opens an electrical circuit to the retraction mechanism, making it impossible to raise the gear.

Question 4

A pilot reports a violent, uncontrolled, side-to-side oscillation of the nose wheel during takeoff and landing rolls. Which of the following conditions is the most likely cause?

Accepted Answer

Nose wheel shimmy.

Answer

The condition described is a classic symptom of nose wheel shimmy. This is a rapid, uncontrolled side-to-side oscillation that can be caused by several factors, including worn torque link bushings, an improperly serviced or failing shimmy damper, incorrect tire pressure, or an out-of-balance wheel/tire assembly.

Question 5

When performing a landing gear retraction test, the aircraft should be placed on jacks in a specific configuration. What is a critical reason for this procedure?

Accepted Answer

To ensure the squat switches are in the 'in-flight' or 'unloaded' position.

Answer

Placing an aircraft on jacks allows the landing gear struts to fully extend, releasing the compression on the squat switches (weight-on-wheels switches). This moves the switches into their 'in-flight' configuration, which closes the electrical circuit and allows the landing gear retraction system to be operated from the cockpit for testing purposes.

Airframe Mechanic Certification Practice Test

Airframe Mechanic Certification Practice Test

Free Airframe Mechanic Aircraft Landing Gear Systems Questions and Answers