FAA Mechanic General (AMG) Knowledge Test, Practice Exams

A repair is classified as a MAJOR repair when, if improperly done, it

1. might appreciably affect weight, balance, structural strength, performance, powerplant operation, or flight characteristics. ✓
2. requires more than 100 labor-hours to complete, regardless of the nature, location, or complexity of the work involved.
3. requires the use of calibrated power tools or precision measuring equipment at any point during the task.

Why: 14 CFR 1.1: a major repair is one that, if improperly done, might appreciably affect airworthiness qualities, or that is not done according to accepted practices or cannot be done by elementary operations.

On a micrometer equipped with a vernier scale, the vernier divides 0.001 inch into how many parts?

1. Ten parts, each equal to 0.0001 inch ✓
2. Four parts, each equal to 0.00025 inch
3. Twenty-five parts, each equal to 0.00004 inch

Why: The vernier graduations divide the 0.001 inch thimble division into 10 equal parts, each equal to 0.0001 inch, allowing measurement to ten-thousandths. FAA-H-8083-30B ch.11.

On a micrometer, which parts are the fixed parts and which are the movable parts?

1. Fixed: frame, barrel, and anvil; movable: thimble and spindle ✓
2. Fixed: thimble and spindle; movable: frame, barrel, and anvil
3. Fixed: frame, thimble, and spindle; movable: barrel and anvil

Why: The fixed parts of a micrometer are the frame, barrel, and anvil; the movable parts are the thimble and spindle. Turning the thimble rotates the spindle. FAA-H-8083-30B ch.11.

What is the main source of corrosion in aircraft?

1. Water or water vapor containing salt combining with oxygen in the atmosphere ✓
2. Direct sunlight and ultraviolet exposure breaking down the metal's oxide film
3. Vibration and cyclic mechanical stress fracturing the protective surface coating

Why: Water or water vapor containing salt combines with oxygen in the atmosphere to produce the main source of corrosion in aircraft. FAA-H-8083-30B ch.8.

Flexible hose stock should be stored

1. in a cool, dark, dry area, protected from ozone and sunlight. ✓
2. hanging in direct sunlight so moisture cannot accumulate.
3. pressurized with dry nitrogen at all times.

Why: Rubber hose deteriorates with heat, light, and ozone, so stock is stored cool, dark, and dry per AC 43.13-1B and hose manufacturer data. (PTFE hose, by contrast, has practically unlimited storage life per FAA-H-8083-30B ch.9.)

What is the likely result, if any, of servicing and charging nickel-cadmium and lead acid batteries together in the same service area?

1. The electrolytes in each battery are the same, so there are no significant differences.
2. The nickel-cadmium would not be affected, but the lead acid battery could become contaminated.
3. Contamination of both types of batteries would occur. ✓

Why: Servicing nickel-cadmium (alkaline) and lead-acid (acid) batteries in the same area cross-contaminates the electrolytes of both types. FAA-H-8083-30B ch.12.

When tightening the B-nut on a hose or line fitting, the mechanic should

1. use two wrenches - one to hold the fitting hex, one to turn the nut. ✓
2. turn the entire hose to run the nut down evenly.
3. tighten until the lay line begins to spiral, then back off slightly.

Why: Holding the fitting with a second wrench prevents twisting the line or hose while the B-nut is torqued. FAA-H-8083-30B ch.9.

Safety wire must be installed so that

1. tension in the wire pulls the fastener toward the tightening direction. ✓
2. the wire is slack enough to allow the fastener one full turn.
3. it passes over the head of the fastener in the loosening direction.

Why: Correctly routed safety wire tightens if the fastener tries to rotate loose - the wire always pulls toward tightening. FAA-H-8083-30B ch.7.

On large aircraft, center of gravity position is commonly expressed as

1. a percentage of the mean aerodynamic chord (MAC). ✓
2. a fraction of the fuselage station numbering.
3. inches forward of the main gear axle.

Why: Large-aircraft CG limits are typically stated in percent MAC; %MAC = (CG - LEMAC) / MAC x 100. FAA-H-8083-30B ch.6.

What is used to indicate that a surface must be machine finished?

1. Text.
2. Leader lines.
3. Finished marks. ✓

Why: Finish marks indicate that a surface must be machine finished. FAA-H-8083-30B ch.4.

An aircraft must not be fueled within what distance of operating ground radar?

1. Within 500 feet of operating ground radar ✓
2. Within 100 feet of operating ground radar
3. Within 50 feet of operating ground radar

Why: Do not fuel an aircraft within 500 feet of operating ground radar. FAA-H-8083-30B ch.1.

When a partially completed job is transferred at a shift change, what communication is required?

1. Both oral and written communication between the technician who started the job and the one continuing it ✓
2. Written communication only, since a properly completed job card fully documents every single step that has been performed
3. Oral communication only, since a thorough face-to-face briefing conveys far more useful detail than any written paperwork

Why: It is vital that work not be continued without both oral and written communication between the technician who started the job and the technician continuing it; absence of either serves as a warning that an error could occur. FAA-H-8083-30B ch.14.

Before use, which NDI methods require properly calibrated equipment and a controlling reference standard?

1. Eddy current, x-ray, and ultrasonic inspection ✓
2. Visual inspection and dye-penetrant inspection
3. Magnetic particle and borescope inspection

Why: The eddy current, x-ray, and ultrasonic inspection methods require properly calibrated equipment (calibrated each time used) and a controlling reference standard to obtain reliable results. FAA-H-8083-30B ch.8 (corrosion inspection NDI discussion); ch.10 General Techniques adds that calibration must be current before NDI.

Rivets in a properly designed sheet metal joint are loaded primarily in

1. shear. ✓
2. tension.
3. torsion.

Why: Riveted joints transfer load across the rivet shank in shear; rivets are weak in tension and are not designed to carry it. FAA-H-8083-30B ch.7.

Following the order of operations, 4 + 6 x 3^2 equals

1. 58 ✓
2. 90
3. 40

Why: Exponents first (3^2 = 9), then multiplication (6 x 9 = 54), then addition: 4 + 54 = 58. FAA-H-8083-30B ch.3 (order of operations).

A fastener requires 240 inch-pounds of torque. Using a 10-inch torque wrench with a 2-inch drive-end extension in line with the wrench, the wrench should be set to

1. 200 inch-pounds. ✓
2. 240 inch-pounds.
3. 288 inch-pounds.

Why: Wrench setting = desired torque x wrench length / (wrench length + extension) = 240 x 10 / 12 = 200 in-lb; using a drive-end extension makes the formula mandatory. FAA-H-8083-30B ch.7.

Which of the following is Newtons First Law of Motion, generally termed the Law of Inertia?

1. To every action there is an equal and opposite reaction, if a force is applied to an object, the object will supply a resistive force exactly equal to and in the opposite direction of the force applied.
2. Force is proportional to the product of mass and acceleration, when a force acts upon a body, the momentum of that body is changed.
3. Objects at rest tend to remain at rest and objects in motion tend to remain in motion at the same speed and in the same direction, unless acted on by an external force. ✓

Why: Newton's First Law (Law of Inertia): objects at rest remain at rest and objects in motion remain in motion at the same speed and direction unless acted on by an external force. FAA-H-8083-30B ch.5.

While torquing a flare nut, a mechanic feels the joint suddenly loosen as the flare gives way. The correct action is to

1. remove the line, cut off the damaged flare, and form a new flare before reinstalling. ✓
2. continue tightening the nut in small increments until the leak-check passes.
3. wrap the damaged flare with PTFE tape, re-torque the nut, and leak-check.

Why: A sheared or cracked flare cannot seal; the damaged flare is cut away and re-flared (or the tube replaced). Tape or extra torque never repairs a failed flare. FAA-H-8083-30B ch.9.

Which NDI methods require properly calibrated equipment and a controlling reference standard for reliable results?

1. Eddy current, x-ray, and ultrasonic inspection ✓
2. Visual inspection and the sense of touch
3. Liquid penetrant and simple magnifier inspection

Why: Eddy current, x-ray, and ultrasonic inspection methods require properly calibrated equipment (calibrated each time used) and a controlling reference standard to obtain reliable results. FAA-H-8083-30B ch.8.

Before starting a radial engine that has been shut down for more than 30 minutes, what must be done?

1. Turn the propeller three or four complete revolutions by hand to detect a hydraulic lock ✓
2. Motor the engine with the starter for one full minute to clear any pooled fuel
3. Prime the engine with several strokes to ensure the lower cylinders are charged with fuel

Why: Before starting a radial engine shut down for more than 30 minutes, check the ignition switch off and turn the propeller three or four complete revolutions by hand to detect a hydraulic lock. FAA-H-8083-30B ch.1.

An inoperative instrument on a part 91 aircraft without a minimum equipment list may be deferred if it is not required equipment and it is

1. removed or deactivated, and placarded 'inoperative'. ✓
2. reported to the FAA within 48 hours of discovery.
3. scheduled for repair at the next annual inspection, with no other action.

Why: 14 CFR 91.213(d)(3): the inoperative item must be removed (with record entry) or deactivated, and placarded 'inoperative'.

The downwash of air leaving the trailing edge of a wing produces lift as an example of which of Newton's laws?

1. Newton's third law (for every action there is an equal and opposite reaction) ✓
2. Newton's first law (a body at rest tends to stay at rest)
3. Newton's law of universal gravitation (particles attract one another)

Why: The downward deflection of the airstream (downwash) creates lift as the reaction to an action, illustrating Newton's third law. FAA-H-8083-30B ch.5.

Who identified the twelve human factors known as the 'Dirty Dozen'?

1. Transport Canada, in response to maintenance-related accidents of the late 1980s and early 1990s ✓
2. The U.S. Federal Aviation Administration, following the first human factors conference in 1988
3. Boeing, as part of developing the Maintenance Error Decision Aid investigation process

Why: Transport Canada identified the twelve human factors known as the 'dirty dozen' after a number of maintenance-related accidents in the late 1980s and early 1990s; the industry adopted them to discuss maintenance human error. FAA-H-8083-30B ch.14.

How does complacency typically develop in an aviation maintenance technician?

1. Over time, as the technician gains experience and a sense of self-satisfaction and false confidence develops ✓
2. Suddenly, as the result of a single overwhelming workload encountered during a compressed inspection cycle near a deadline
3. Immediately, when a newly hired technician simply lacks the training and experience needed to recognize a developing fault

Why: Complacency typically develops over time; as a technician gains knowledge and experience, self-satisfaction and false confidence may cause a repetitive task or inspection item to be overlooked. FAA-H-8083-30B ch.14.

Pascal's law states that pressure set up in a confined fluid acts how?

1. Equally in all directions, at right angles to the containing surfaces ✓
2. Only in the direction of the applied force, along the axis of the piston
3. Downward toward the bottom of the container in proportion to depth only

Why: Pascal's law: pressure set up in a confined fluid acts equally in all directions and at right angles to the containing surfaces; this is the foundation of hydraulics. FAA-H-8083-30B ch.5.

Low-pressure hose connections made with beads and hose clamps are appropriate for

1. low- or medium-pressure systems such as vacuum, instrument air, or coolant lines. ✓
2. hydraulic system pressure lines operating at working pressures up to 3,000 psi
3. oxygen system plumbing of any operating pressure or diameter.

Why: Bead-and-clamp connections suit low- or medium-pressure uses such as vacuum, instrument air, and coolant lines; pressure systems require flare, flareless, or swaged fittings. FAA-H-8083-30B ch.9.

A relay is best described as

1. a switch operated electrically by a small control current to switch a larger current. ✓
2. a variable resistor used to limit current flow in high-load power distribution circuits.
3. a protective device that automatically opens the circuit whenever it senses an overcurrent.

Why: A relay uses a small coil current to close or open contacts carrying a much larger load current, allowing remote control. FAA-H-8083-30B ch.12.

What is the product of (-6) x (+4)?

1. -24 ✓
2. 24
3. -10

Why: A negative number multiplied by a positive number gives a negative product: (-6) x (+4) = -24. FAA-H-8083-30B ch.3 (signed numbers).

What is the most effective barrier between metal surfaces and corrosive media?

1. A good, intact paint finish, such as catalyzed polyurethane enamel or two-part epoxy ✓
2. A film of viscous preservative oil applied liberally to all exposed surfaces
3. A layer of grease packed into every seam, joint, and fastener recess

Why: A good, intact paint finish is the most effective barrier between metal surfaces and corrosive media; common finishes include catalyzed polyurethane enamel, waterborne polyurethane enamel, and two-part epoxy paint. FAA-H-8083-30B ch.8.

The 'Environment' element of the PEAR model addresses which two environments in aviation maintenance?

1. The physical workplace and the organizational environment within the company ✓
2. The indoor hangar environment and the outdoor flight-line weather environment
3. The regulatory environment and the economic environment of the airline industry

Why: A human factors program must address at least two environments: the physical workplace (ramp, hangar, shop) and the organizational environment that exists within the company. FAA-H-8083-30B ch.14.

A fastener diameter of 0.25 inch expressed in millimeters is

1. 6.35 mm. ✓
2. 2.54 mm.
3. 25.4 mm.

Why: One inch = 25.4 mm, so 0.25 x 25.4 = 6.35 mm. FAA-H-8083-30B ch.3 (metric conversion).

An item located forward of the datum produces

1. a negative moment. ✓
2. a positive moment.
3. no moment, regardless of weight.

Why: Locations forward of the datum carry negative arms, so their moments are negative in the CG calculation. FAA-H-8083-30B ch.6.

A block diagram is most useful for

1. understanding and troubleshooting the operation of a complex system at a functional level. ✓
2. fabricating a replacement part to exact dimensions with all required tolerances applied.
3. determining the rivet spacing and edge distance for a sheet metal structural repair.

Why: Block diagrams represent units as simple blocks to show functional relationships - a troubleshooting aid, not a fabrication document. FAA-H-8083-30B ch.4.

How is the specific gravity of a substance defined?

1. The ratio of the density of the substance to the density of water, expressed as a pure number with no units ✓
2. The weight of the substance divided by its total volume, expressed in pounds per cubic foot of the sample
3. The ratio of the substance mass to its acceleration under gravity, expressed in slugs per cubic inch

Why: Specific gravity is the ratio of the density of a substance to the density of water; because it is a ratio it is a pure number with no units. FAA-H-8083-30B ch.5.

As defined in 14 CFR part 1, 'time in service' for maintenance records is the time from

1. the moment the aircraft leaves the surface of the earth until it touches it at the next point of landing. ✓
2. engine start before takeoff until complete engine shutdown after landing and taxi-in
3. the moment the aircraft first moves under its own power for the purpose of flight until it comes to rest after landing

Why: 14 CFR 1.1: time in service is counted from wheels-off to touchdown - not block-to-block or engine start to shutdown.

A torque indication of 840 inch-pounds is known to read 5 percent high. What is the actual torque being applied?

1. 800 inch-pounds ✓
2. 798 inch-pounds
3. 882 inch-pounds

Why: Indicated = actual x 1.05, so actual = 840 / 1.05 = 800 inch-pounds. Subtracting 5% of the indication (840 x 0.95 = 798) is the common error. FAA-H-8083-30B ch.3 (percentage).

If a mechanic wants to comply with an airworthiness directive using a different method than the AD specifies, the alternative method of compliance (AMOC) must be

1. approved by the FAA office identified in the AD before it is used. ✓
2. documented in the aircraft records and used at the mechanic's discretion.
3. signed off by any mechanic holding an Inspection Authorization.

Why: 14 CFR 39.19: anyone may propose an AMOC, but it must be approved by the FAA (the office specified in the AD) before being used.

Fluid line fitting nuts should be tightened with a torque wrench primarily because

1. overtightening can damage the flare or fitting and undertightening allows leaks. ✓
2. hand-tight connections are acceptable on fuel and oil lines below 40 psi operating pressure
3. the torque value determines the fluid flow rate through the line.

Why: Correct torque protects the sealing surfaces: too tight damages the flare/sleeve, too loose leaks. FAA-H-8083-30B ch.9.

If a part to be inspected for surface defects is made of a magnetic material, which inspection method is generally recommended?

1. Magnetic particle inspection ✓
2. Liquid penetrant inspection
3. Ultrasonic inspection

Why: If the part in question is made of a magnetic material, magnetic particle inspection is generally recommended over penetrant inspection. FAA-H-8083-30B ch.10.

Why must oxygen servicing not be performed during fueling or defueling of the aircraft?

1. Those operations could provide a source of ignition for the oxygen-enriched environment ✓
2. The fuel vapors would contaminate the breathing oxygen and make the crew sick
3. The aircraft cannot be grounded for two separate servicing operations at the same time

Why: Do not service aircraft with oxygen during fueling, defueling, or other maintenance that could provide a source of ignition; combustible materials ignite more rapidly in an oxygen-rich atmosphere. FAA-H-8083-30B ch.1.

Which class of fire involves energized electrical wiring and equipment?

1. Class C ✓
2. Class B
3. Class A

Why: Class C fires involve energized electrical wiring and equipment. Class A is ordinary combustibles, Class B is flammable liquids, Class D is flammable metal. FAA-H-8083-30B ch.1.

The list on a drawing that specifies the materials and parts required to fabricate an assembly is the

1. bill of materials. ✓
2. revision block.
3. application block.

Why: The bill of materials is a ruled list of the materials, parts, and quantities needed to make the assembly. FAA-H-8083-30B ch.4.

A mechanic checks a de-energized circuit with an ohmmeter and reads infinite resistance between the two ends of a wire. This indicates

1. an open in the wire. ✓
2. a short circuit to ground.
3. normal continuity.

Why: Infinite resistance means no continuous path - an open conductor. Continuity shows near-zero resistance. FAA-H-8083-30B ch.12.

An aircraft has a total weight of 2,000 pounds and a total moment of 170,000 inch-pounds. Its center of gravity is

1. 85 inches aft of the datum. ✓
2. 117.6 inches aft of the datum.
3. 34 inches aft of the datum.

Why: CG = total moment / total weight = 170,000 / 2,000 = 85 inches aft of the datum. FAA-H-8083-30B ch.6.

Which high-strength aluminum alloys are especially susceptible to intergranular corrosion when improperly heat-treated?

1. 2014 and 7075 ✓
2. 1100 and 3003
3. 2024 and 6061

Why: High-strength aluminum alloys such as 2014 and 7075 are more susceptible to intergranular corrosion if improperly heat-treated and then exposed to a corrosive environment. FAA-H-8083-30B ch.8.

The human factor 'lack of awareness' is defined as what?

1. A failure to recognize all the consequences of an action, or a lack of foresight ✓
2. A failure to express one's concerns to management in a positive, productive manner
3. A failure to obtain the latest technical data before beginning a maintenance task

Why: Lack of awareness is defined as a failure to recognize all the consequences of an action or a lack of foresight; it is common when the same task is performed repeatedly. FAA-H-8083-30B ch.14.

Using the law of exponents, 2^3 x 2^2 equals

1. 32 ✓
2. 64
3. 16

Why: When multiplying powers of the same base, add the exponents: 2^(3+2) = 2^5 = 32. FAA-H-8083-30B ch.3 (law of exponents).

An acceptable completed weld is characterized by

1. a smooth bead of uniform width with regular ripples and no burn-through or porosity. ✓
2. a bead that has been ground flush and polished to remove the ripple pattern.
3. a heavy built-up bead with occasional small pinholes to relieve stresses.

Why: A good weld is uniform in width with even ripples well feathered into the base metal, and free of gas pockets, porosity, and inclusions. FAA-H-8083-30B ch.10 (inspection of welds).

The line on a drawing that shows where a sectional view is taken is the

1. cutting plane line. ✓
2. phantom line.
3. dimension line.

Why: A cutting plane line indicates the plane along which the object is imagined to be cut to produce the sectional view. FAA-H-8083-30B ch.4.

What are the three methods of cleaning the exterior of an aircraft?

1. Wet wash, dry wash, and polishing ✓
2. Solvent wipe, steam clean, and abrasive blast
3. Emulsion soak, alkaline dip, and hand buffing

Why: There are three methods of cleaning the aircraft exterior: wet wash, dry wash, and polishing (polishing further broken into hand and mechanical polishing). FAA-H-8083-30B ch.8.

By how much may the 100-hour inspection time be exceeded, and how is the overflown time handled?

1. Up to 10 hours, only to reach a place for inspection; the excess is counted against the next 100 hours ✓
2. Up to 25 hours, for any reason; the excess resets the next inspection interval to a full 100 hours
3. Up to 50 hours, only if the aircraft is ferried empty; the excess is disregarded

Why: An aircraft may be flown up to 10 hours beyond the 100-hour limit if necessary to reach a place for inspection, but the excess time is counted against the next 100-hour interval. FAA-H-8083-30B ch.10.

A 6-ohm resistor is connected in series with two 10-ohm resistors that are in parallel with each other. The total circuit resistance is

1. 11 ohms. ✓
2. 26 ohms.
3. 8 ohms.

Why: The parallel pair: 10 x 10 / 20 = 5 ohms; adding the series 6 ohms gives 11 ohms total. FAA-H-8083-30B ch.12.

The binary number 110 equals what decimal number?

1. 6 ✓
2. 3
3. 12

Why: 110 binary = (1x4) + (1x2) + (0x1) = 6. FAA-H-8083-30B ch.3 (the binary number system).

After completing a major repair, the mechanic gives a signed copy of FAA Form 337 to the aircraft owner and forwards the other copy to the FAA within

1. 48 hours after the aircraft is approved for return to service. ✓
2. 10 days after the work is completed.
3. 30 days after the entry is made in the aircraft records.

Why: 14 CFR part 43 Appendix B: a signed copy of Form 337 goes to the aircraft owner, and a copy is forwarded to the FAA Aircraft Registration Branch within 48 hours after the aircraft is approved for return to service.

Which set of measures is used to control foreign object damage (FOD)?

1. Keep ramp and operation areas clean, maintain a tool control program, and provide receptacles for used hardware ✓
2. Inspect all fasteners with a magnifier, torque them to spec, and lockwire every accessible bolt
3. Cover all engine inlets with tape, cordon the ramp, and prohibit any hand tools on the flight line

Why: To control FOD, keep ramp and operation areas clean, have a tool control program, and provide convenient receptacles for used hardware, shop towels, and other consumables. FAA-H-8083-30B ch.1.

A sectional view of a part is used on a drawing to show

1. the interior construction that cannot be shown by outside views. ✓
2. the finished surface texture required by the specification.
3. the sequence in which the part is assembled.

Why: Sectional views expose interior features by showing the part as if cut open along the cutting plane. FAA-H-8083-30B ch.4.

Self-locking nuts may be used on aircraft provided that

1. the head of the bolt is safety wired.
2. it is installed with a lock washer.
3. the bolt or nut is not subject to rotation. ✓

Why: Self-locking nuts may be used on aircraft provided the bolt or nut is not subject to rotation. FAA-H-8083-30B ch.7.