CORROSION
Which of these materials is most anodic? Magnesium, Zinc, Cadmium, 7075 Aluminum alloy, 2024 Aluminum alloy, Mild Steel, Copper, Stainless Steel, Chromium, Gold.
Magnesium
Rationale: Magnesium is the most anodic of these materials. Some of the common metals in the order of their electrochemical activity are: Magnesium, Zinc, Cadmium, 7075 Aluminum alloy, 2024 Aluminum alloy, Mild Steel, Copper, Stainless Steel, Chromium, Gold.
Why are exploded views helpful for AMTs?
They show parts separated to see how they fit together.
Rationale: Exploded views visually show how parts relate to each other and how they fit together, helping AMTs put them together accurately. This helps AMTs understand part relationships during assembly.
You are tasked with measuring the outside diameter of a shaft that must fit within a specific tolerance. You have a steel ruler, a caliper, and a micrometer available. Which tool should you select, and why?
Use the micrometer because it provides the highest level of precision needed for tight tolerance measurements.
Rationale: Micrometers provide thousandths of an inch precision, critical for tight tolerance components.
Where is an AN clevis bolt used in an airplane?
Only in shear load applications
Rationale: A clevis bolt should be used only where the load to which the bolt is applied is a shear load. A clevis bolt is not designed to take any type of tensile load. The threaded portion of a clevis bolt is short and there is a groove between the threads and the shank. The head of a clevis bolt has a screwdriver slot rather than flats for the use of a wrench.
What is Alclad aluminum?
Pure aluminum layered over an aluminum alloy core for corrosion resistance.
Rationale: Alclad consists of a pure aluminum layer bonded to an aluminum alloy for corrosion resistance and strength.
What is a “fisheye” defect in aircraft paint?
Small round spots where paint pulls away, exposing the surface
Rationale: This is the standard description of a “fisheye” defect, often caused by surface contamination like oil or silicone.
What is the most significant reason for using Alclad instead of pure aluminum when forming aircraft skins?
It provides a corrosion-resistant layer while maintaining the strength of the aluminum alloy core.
Rationale: Alclad uses a thin, pure aluminum layer to resist corrosion while maintaining the alloy’s strength inside.
What type of diagram would a mechanic use for troubleshooting?
Schematic Diagram
As electrons pass from the Anode to the Cathode, which one corrodes?
Anode
Rationale: As electrons are passed from the anode to the cathode, the anode deteriorates as its electrons are diminished.
Which type of diagram shows a simplified system overview?
Block diagram
Rationale: Block diagrams give a simplified overview of a system. They help you understand the basic functions of connected parts.
What is the purpose of the vernier scale on calipers and micrometers?
To allow for more precise readings
Rationale: The vernier scale provides fine measurement subdivisions, allowing readings to be taken with greater accuracy than the main scale alone.
Why is it important for an AMT to inspect O-rings on hydraulic lines for cracks and hardening during routine maintenance?
It can allow hydraulic fluid leaks, leading to system failures or loss of control.
Rationale: Cracked or hardened O-rings can leak, causing hydraulic system failures,which can lead to serious safety issues.
Which letter designates a metal is in its annealed condition?
-O
Rationale: In the temper designations used with aluminum alloy, “O” means the metal has been annealed.
After cleaning a metal surface on the aircraft, what should the AMT do next to ensure proper paint adhesion and corrosion protection?
Clean the surface well and check for dust, oil, or water before painting.
Rationale: Proper cleaning removes contaminants that prevent paint from bonding effectively and protects against corrosion.
The side clearances of piston rings are measured with a:
Thickness gauge
Rationale: A thickness gauge is used to measure gaps/clearances/distances between surfaces
A hydraulic system schematic drawing typically indicates the what?
The direction of fluid flow through the system.
While cleaning corrosion from an aluminum component, you observe localized pitting after removing the surface corrosion. What is the appropriate next step before applying alodine?
Ensure all corrosion is removed and inspect the area for remaining pitting.
Rationale: Before applying alodine, the surface must be free of corrosion and cleaned thoroughly. Pitting indicates deeper corrosion, which must be fully removed to prevent structural degradation and ensure proper bonding of chemical treatments.
Why are the notes included on maintenance drawings important to a technician?
They provide additional instructions not easily shown graphically.
Rationale: Notes give instructions, tolerances, and references critical for safe, compliant work.
Why is it important for an AMT to use the ratchet feature on a micrometer instead of turning the thimble directly when measuring engine components?
The ratchet allows consistent measuring pressure, ensuring repeatable and accurate measurements.
Rationale: The ratchet applies consistent pressure to prevent overtightening, avoiding part deformation and ensuring measurement accuracy across users.
Aircraft bolt threads are what fit?
Class 3
Rationale: Aircraft bolt threads are a class 3 fit (medium fit).
Which property of metals describes how much a material expands when heated?
Thermal expansion
Rationale: Thermal expansion describes size changes with temperature.
What is plastic media blasting (PMB) used for during surface preparation?
To gently remove paint and rust without damaging surfaces.
Rationale: PMB uses soft plastic particles to safely strip paint and light corrosion from aircraft skins and delicate surfaces without damaging underlying material
(especially aluminum).
The letter “A” appearing at the end of a part number for a bolt indicates?
Undrilled shank
Rationale: The letter “A” after the dash number in a bolt part number indicates “no hole in the shank”
Working drawings may be divided into three classes. They are:
Detail drawings, assembly drawings, and installation drawings.
How is corrosion commonly described in aviation?
Metal returning to its natural state.
Rationale: Aluminum oxide does not evaporate, and iron oxide does not remain protective.
Which type of pictorial drawing shows a 3D object with combined views?
Isometric
Rationale: Isometric drawings show multiple sides of an object tilted at equal angles, giving a 3D-like view without perspective distortion.
Convert 480 inch-lbs. to foot-lbs.
40 ft-lbs
Rationale: Divide 480 inch-lbs. by 12 to convert to foot-lbs. = 40 ft. lbs.
A rivet with a dimple on the head is made of:
2117
Rationale: A rivet made of 2117 is identified by a dimple or recessed dot head marking.
What is the property, which enables a metal to carry heat or electricity?
Conductivity
Rationale: Conductivity is the property that enables a metal to carry heat or electricity.
An AMT has just finished painting a wing panel and observes an orange peel texture on the surface. What should the AMT do before attempting to repaint the panel to ensure a smooth finish?
Check and adjust the paint viscosity, thinner ratio, and spray technique according to specifications.
Rationale: These are the appropriate procedural adjustments to address and prevent orange peel after identifying a surface defect.
If it is necessary to accurately measure the diameter of a hole approximately ¼ inch in diameter, the mechanic should use a:
Small-hole gauge and determine the size of the hole by taking a micrometer reading of the ball end of the gauge
Rationale: A small hole gauge is a precision measuring tool used with an outside micrometer to find the internal diameter of small holes (up to ¼”), acting as a transfer gauge by expanding to fit snugly inside the bore and then being measured externally for an indirect reading, ideal for parts like valve guides where standard inside micrometers or telescoping gauges won't fit.
What is the class of working drawing that describes or depicts a single part?
Detail Drawing
What type of corrosion is typically indicated by white/gray powder deposits on aluminum surfaces?
Aluminum corrosion
Rationale: Corrosion of aluminum often produces white, powdery or puffy deposits which are a known visual indicator specific to this metal.
A solid line with one arrowhead is called a:
Leader line
Rationale: Leader lines are solid lines with one arrowhead.
Find the torque wrench indication required to torque a bolt to 700 foot-pounds with a torque wrench 66.5 inches long and an extension of 7 inches long. Use the formula (T x L / L + E)
633.3 in-lbs
Rationale: Substitute the values in the formula: 700 in-lbs x 66.5 inches / 66.5 inches + 7 inches = 633.33 in. lbs
What does the “H” signify in the following part number? AN6H34
The head is drilled for safety wire
Rationale: The letter “H” between the diameter and length indicates a hole in the head, used for safety wire.
Why is annealing used on aluminum alloys before forming complex aircraft components?
To soften the aluminum, restoring ductility and reducing cracking during forming.
Rationale: Annealing relieves internal stresses, restores ductility, and allows aluminum to be formed into complex shapes without cracking.
What is the primary purpose of using sandwich panels in aircraft construction?
To increase strength while minimizing weight
Rationale: These panels consist of two strong outer layers (face sheets) and a lightweight core, providing excellent strength-to-weight performance, which is ideal for aircraft structures.
You are tasked with priming a bare, aluminum part on an aircraft before painting. Which primer should you use to ensure corrosion resistance and proper topcoat adhesion?
Epoxy Primer
Rationale: Epoxy primers are widely used on aircraft aluminum due to their strong adhesion, corrosion resistance, and chemical durability. They are ideal under most topcoats.
Objects of uniform thickness, gaskets, shims, and plates might be represented by what type of drawing?
One-View Drawings