Free Airframe Mechanic Assembly and Rigging Questions and Answers

Question 1

A technician is inspecting a properly tensioned turnbuckle in a primary flight control system and observes four threads are exposed between the barrel and the cable end fitting. What is the correct course of action?

Accepted Answer

Replace the turnbuckle with one of a more appropriate length.

Answer

According to standard aircraft maintenance practices (such as those in AC 43.13-1B), no more than three threads should be exposed on either end of a turnbuckle barrel. Exposing four or more threads indicates insufficient thread engagement, which compromises the strength of the connection. The correct action is to use a turnbuckle of the proper length to achieve the correct cable tension while ensuring adequate thread engagement.

Question 2

What is the primary reason that aircraft maintenance manuals provide a temperature/tension chart for rigging flight control cables?

Accepted Answer

To compensate for the different thermal expansion rates of the aluminum airframe and the steel cables.

Answer

Aircraft structures, typically made of aluminum alloys, expand and contract at a different rate than the steel control cables when subjected to temperature changes. A temperature/tension chart allows a technician to set the correct cable tension at a given ambient temperature, ensuring that the tension will remain within the specified limits whether the aircraft is on a hot ramp or at high altitude where temperatures are very low.

Question 3

After an aileron has been repainted, it must be rebalanced. Which of the following is the most critical reason for this procedure?

Accepted Answer

To prevent the onset of high-frequency control surface flutter.

Answer

Adding paint adds weight to the control surface. If this weight is not distributed correctly relative to the hinge line, it can change the surface's center of gravity. An improperly balanced control surface is highly susceptible to flutter, a rapid and destructive oscillation caused by the interaction of aerodynamic, inertial, and elastic forces, which can lead to catastrophic structural failure.

Question 4

Before checking the wing dihedral and incidence angles during a rigging check, what is the most critical preparatory step?

Accepted Answer

Leveling the aircraft both longitudinally and laterally according to the maintenance manual.

Answer

All airframe alignment and rigging measurements must be taken from a specific, known reference plane. The aircraft must first be leveled according to the manufacturer's specific instructions and leveling points (often using a spirit level or plumb bob). Performing these checks on an un-level aircraft will result in inaccurate measurements and improper rigging.

Question 5

During an inspection of a control cable passing over a pulley, a single broken wire is discovered. According to FAA AC 43.13-1B, what action is required?

Accepted Answer

The entire control cable assembly must be replaced.

Answer

According to FAA guidance in AC 43.13-1B, any cable assembly that has even one broken wire strand located in a critical fatigue area must be replaced. A critical fatigue area includes any section where the cable runs over a pulley, through a fairlead, or within one foot of a swaged fitting.

Airframe Mechanic Certification Practice Test

Airframe Mechanic Certification Practice Test

Free Airframe Mechanic Assembly and Rigging Questions and Answers