Mixed Deck — All AMT Topics Flashcards

When inspecting a wood propeller, small cracks running parallel to the grain are typically treated by:

Answer: Rejecting the propeller from service

Cracks parallel to the grain in a wood propeller are cause for rejection because they can rapidly propagate and lead to structural failure.

A technician is fabricating a bracket from a sheet of 0.040-inch thick aluminum alloy. The plans call for a single 90-degree bend with an inside bend radius of 0.125 inches. What is the correct setback for this bend?

Answer: 0.165 inches

For a 90-degree bend, the setback is calculated using the formula: Setback (SB) = Bend Radius (BR) + Material Thickness (MT). In this case, SB = 0.125" (BR) + 0.040" (MT), which equals 0.165 inches. The setback value is used to determine the location of the bend tangent line on the flat layout.

What is the primary reason for using a dual ignition system on a certified aircraft reciprocating engine?

Answer: To provide redundancy for safety and improve combustion efficiency for better performance.

A dual ignition system uses two separate magnetos, harnesses, and spark plugs for each cylinder. This provides redundancy, meaning if one entire system fails, the engine can still operate on the other. Additionally, having two spark plugs ignites the fuel-air mixture from two points, leading to a faster, more complete combustion process, which improves engine performance and power output.

What is the purpose of safety wiring in aviation maintenance?

Answer: To prevent fastener loosening

Safety wiring is a mechanical locking device used to secure fasteners, such as nuts, bolts, and turnbuckles, in critical aircraft applications. It ensures that these components remain tight and do not vibrate loose during operation, thereby preventing potential system failures and maintaining structural integrity. This simple yet effective method is a cornerstone of aviation safety.

The station at which propeller blade angle is typically measured and adjusted is located:

Answer: At 75% of the blade radius from the center

Blade angle is measured and specified at 75% of the propeller radius because this station best represents the average aerodynamic performance of the blade.

According to 14 CFR Part 91.409, large airplanes operated under Part 91 must have a progressive inspection program or comply with which inspection requirement?

Answer: An annual inspection and 100-hour inspection if used for hire

Under Part 91.409, large aircraft not operated under a Part 121 or 135 program must undergo an annual inspection and, if used for hire, a 100-hour inspection.

Which of the following is NOT included in the aircraft's basic empty weight?

Answer: Usable fuel

Basic empty weight includes the airframe, engines, fixed equipment, unusable fuel, and full oil, but NOT usable fuel which is part of useful load.

When weighing an aircraft, tare weight refers to:

Answer: The weight of chocks, jacks, or equipment placed on the scales that must be subtracted

Tare weight is the weight of any equipment (chocks, blocks, etc.) placed on the scales during weighing that must be subtracted to get the actual aircraft weight.

What effect does elevated temperature have on hydraulic fluid viscosity?

Answer: Viscosity decreases, potentially causing increased leakage and wear

Higher temperatures reduce hydraulic fluid viscosity, which can increase internal leakage past seals and accelerate component wear.

A technician installs a new GPS/NAV/COMM system that was not part of the aircraft's original type design. This installation is determined to be a major alteration. Which form is required to be completed and submitted to the FAA to document this work?

Answer: FAA Form 337

According to 14 CFR Part 43, a major alteration requires the completion of FAA Form 337, Major Repair and Alteration. This form provides a detailed record of the work performed and the data used to approve the aircraft for return to service. A copy is given to the owner and another is sent to the FAA to become part of the aircraft's permanent records.

During an inspection of a high-time aircraft's wing structure, a technician discovers evidence of corrosion that appears to be attacking the metal along the grain boundaries. This has led to a lifting or flaking of the metal surface. This describes which form of corrosion?

Answer: Exfoliation corrosion

Exfoliation corrosion is an advanced form of intergranular corrosion where the corrosive attack along the grain boundaries causes the surface layers of the metal to lift up and flake off. This type of damage is particularly severe as it delaminates the material, compromising its structural integrity.

Which propeller type uses aerodynamic twisting moment as the primary force to increase blade pitch?

Answer: Hydromatic (Hamilton Standard) propeller

The Hydromatic propeller design relies on aerodynamic twisting moment combined with counterweights to move blades toward high pitch, with oil pressure moving blades toward low pitch.

A propeller is equipped with electrically heated de-ice boots on the leading edges of the blades. How does this system typically operate to remove ice?

Answer: The boots are heated in a repeating cycle, melting the layer of ice closest to the blade so it can be thrown off by centrifugal force.

Propeller de-ice systems work by cyclically heating the elements in the boots. This heating is not meant to evaporate all the ice, but rather to melt the thin layer adhering to the blade surface. Once this bond is broken, the centrifugal force of the rotating propeller slings the remaining ice off the blades.

What does a negative dihedral (anhedral) wing configuration primarily provide?

Answer: Decreased lateral stability for improved maneuverability

Anhedral reduces the natural lateral stability (dihedral effect), which is desirable in highly maneuverable or swept-wing high-speed aircraft.

Which of the following best describes a 'phantom load' in an aircraft electrical system?

Answer: A continuous small current drain from devices left energized when the master switch is off

Phantom (or parasitic) loads are small but continuous drains from clocks, memory circuits, or improperly wired equipment that can discharge the battery over time.

When cutting a repair patch from aluminum sheet stock, the corners of rectangular patches should be:

Answer: Clipped or radiused to reduce stress concentration

Square corners on repair patches create stress concentrations that can initiate cracks, so corners must be radiused or clipped.

During turbine engine ground run-up, a 'hung start' is characterized by:

Answer: RPM stabilizing below idle with exhaust temperature continuing to rise

A hung start occurs when the engine lights off but RPM stabilizes at a sub-idle value while EGT continues to rise, risking a hot start.

According to 14 CFR Part 43.9, which of the following is required to be included in a maintenance record entry after performing a repair?

Answer: The signature, certificate number, and kind of certificate held by the person approving the work.

14 CFR 43.9 explicitly requires that a maintenance record entry contain: a description of the work, the date of completion, and if the work was performed satisfactorily, the signature, certificate number, and kind of certificate held by the person approving the work for return to service. Total time-in-service is required for inspection entries under 43.11, not general maintenance entries under 43.9.

In aircraft structural terminology, what is a 'joggle'?

Answer: A small offset in a structural member allowing parts to overlap flush

A joggle is a small step or offset formed into a structural member so that overlapping parts lie flush with each other.

When selecting replacement rivets for a sheet metal repair, you find the original rivets are 2117-T4. What is the primary advantage of this rivet material?

Answer: It can be driven in the as-received condition without heat treatment

2117-T4 (AD) rivets are field-ready because they do not require refrigeration or re-heat treatment before driving.