FAA Aviation Mechanic General (AMG) flashcards

14 CFR 91.409 requires annual and 100-hour inspections to be performed in accordance with the scope and detail specified in 14 CFR Part 43, Appendix D.

• Appendix D lists items like fuselage/hull, cabin/cockpit, engine, landing gear, wing/center section, and more
• Annual inspection required every 12 calendar months for most Part 91 aircraft
• 100-hour inspection required for aircraft used for hire or flight instruction

Memory trick: 'Appendix D = Detail' for what must be checked.

The frequency of an AC generator's output depends on the number of magnetic poles and rotational speed: f = (P x RPM)/120.

• f = (Poles x RPM) / 120
• More poles or higher RPM increases frequency
• Aircraft AC systems standardize on 400 Hz

Memory trick: 'Poles times speed, divided by 120' gives the Hertz.

The sequence of steps used to safely connect and disconnect external ground power to an aircraft.

• Verify voltage/frequency compatibility first
• Output switch OFF before connecting cable
• Monitor gauges continuously during use
• Output switch OFF before disconnecting cable

Memory trick: Plug first, power second — never the reverse.

CG location is found by dividing total moment (sum of each scale weight times its arm) by total aircraft weight.

• Moment = weight × arm (distance from datum)
• Total weight = sum of all scale readings
• CG = total moment ÷ total weight

Memory trick: Moment over weight tells you where the balance sits.

Total resistance in a parallel circuit is always less than the smallest individual resistor because current has multiple paths.

• Formula for two resistors: Rt=(R1×R2)/(R1+R2)
• Rt is always less than smallest branch resistance
• Voltage is same across each branch
• Current divides among branches

Memory trick: Parallel paths make it easier for current, so total resistance drops.

A nondestructive testing method using penetrating radiation to reveal internal flaws such as porosity, cracks, or inclusions inside metal parts.

• Detects internal/subsurface defects invisible to other methods
• Commonly used on castings and welds
• Requires radiation safety precautions and shielding
• Produces a film or digital image showing density variations

Memory trick: "X-rays see through metal like a flashlight through fog."

Fluids used to remove and prevent ice accumulation on aircraft surfaces before flight, categorized by type and holdover time.

• Type I: heated, unthickened, removes ice
• Type IV: thickened, unheated, longest holdover time
• Two-step process common in severe icing conditions

Memory trick: Type IV = Four extra hours of frost-free protection.

A drawing view created by an imaginary cutting plane through an object to reveal internal details not visible from the outside.

• Uses hatching/cross-hatch lines to show cut material
• Common for complex internal components like actuators, valves
• Different from schematic, which is symbolic not physical

Memory trick: Section = 'slice' it open to see the guts

CG is found by dividing the total moment (sum of weight × arm for all items) by the total weight of the aircraft.

• Moment = Weight × Arm
• CG = Total Moment ÷ Total Weight
• Arm is measured from a fixed reference datum

Memory trick: CG = 'Center of Gravity' — total moment split by total weight

Standard atmospheric pressure can be expressed in multiple units: 14.7 psi, 29.92 inHg, or 760 mmHg, all representing the same sea-level condition.

• 1 psi ≈ 2.036 inHg
• Standard sea-level pressure = 14.7 psi = 29.92 inHg = 760 mmHg
• Altimeters and barometers are calibrated using inHg in the US

Memory trick: 'Fourteen-seven gives twenty-nine-ninety-two' — the aviator's pressure pair.

A drawing that shows how detail parts are put together to form a complete unit, typically with item/part numbers and quantities keyed to an accompanying parts list.

• Shows relative position of multiple parts
• References part numbers/quantities, not full dimensions
• Often paired with a bill of materials

Memory trick: Assembly = 'Assemble the puzzle' — see how pieces go together.

Unwritten rules or informal practices that develop in a workplace, often deviating from official procedures, and are perpetuated as 'the way things are done.'

• Passed on informally to new employees
• Often develop because 'nothing bad has happened yet'
• Can undermine formal safety procedures
• Corrected through strong safety culture and supervision

Memory trick: 'This is how we've always done it' — Norms are shortcuts baked into shop culture.

The relationship between voltage, current, and resistance in a DC circuit: E = I × R.

• E = voltage in volts
• I = current in amperes
• R = resistance in ohms
• Rearranged forms: I=E/R and R=E/I

Memory trick: E is up top, I and R hold hands below — cover E to get I×R.

A shortcut formula for calculating total resistance of exactly two parallel resistors: Rt = (R1 x R2)/(R1 + R2).

• Only valid for exactly two resistors at a time
• Result is always less than the smallest resistor
• For more resistors, use the reciprocal formula instead

Memory trick: Product over sum — multiply then divide, and the answer always shrinks below the smallest value.

RMS (root-mean-square) voltage represents the effective DC-equivalent value of an AC waveform and equals 0.707 times the peak voltage.

• Vrms = 0.707 x Vpeak
• Vpeak = Vrms / 0.707 = 1.414 x Vrms
• Standard AC meters display RMS values by default

Memory trick: 'Peak is Prouder' - peak voltage is always larger (1.414x) than RMS.

Prohibits fraudulent or intentionally false entries in maintenance records, applications, or other required documents; violations can lead to certificate action.

• Applies to any required maintenance record or entry.
• Distinct from simple recordkeeping errors under 43.9.
• Can result in suspension or revocation of certificate.

Memory trick: 'Fake sign, lose your wings' — falsification costs your certificate.

A material property describing how much a material's length changes per unit length per degree of temperature change.

• ΔL = L × coefficient × ΔT
• Length must be in consistent units (often inches)
• Different metals have different expansion coefficients

Memory trick: Hot metal stretches — length times rate times rise.

Practices used to identify and remove foreign objects from ramp and taxiway areas to prevent aircraft or engine damage.

• FOD walks are the primary prevention method
• Tool control accountability reduces dropped hardware
• FOD collection containers should be placed on the ramp

Memory trick: A clean ramp is a safe ramp — sweep before you fly.

The fully annealed condition of aluminum alloy, providing maximum ductility for forming operations before subsequent heat treatment.

• O = annealed, softest condition
• Used for severe forming before heat treatment
• T-tempers (T3, T4, T6) are stronger but less ductile

Memory trick: 'O' is Open and soft — bend it before you bake it hard

The weight of the airframe, engines, all fixed equipment, unusable fuel, and full operating fluids (such as engine oil), excluding usable fuel, crew, passengers, and payload.

• Includes unusable fuel and full oil for many aircraft types
• Excludes usable fuel and all payload items
• Useful load = usable fuel + crew + passengers + baggage/cargo

Memory trick: Basic empty = the bare bird plus its 'stuck-in' fluids, nothing removable

At constant temperature, the pressure and volume of a gas are inversely proportional.

• P1V1 = P2V2
• Applies only at constant temperature
• Used for compressed gas systems like oxygen or nitrogen bottles

Memory trick: Squeeze the balloon, pressure grows.

Lenz's Law states that an induced current always flows in a direction that opposes the change in magnetic flux that created it, consistent with conservation of energy.

• Induced current opposes the change causing it
• Based on conservation of energy
• Complements Faraday's Law which gives magnitude of induced EMF

Memory trick: 'Lenz Resists the Change' - nature opposes what disturbs it.

AN bolt heads carry raised or recessed symbols identifying material and grade, allowing technicians to verify correct bolt use without disassembly.

• No marking = commercial-grade bolt, not for aircraft primary structure
• One raised dash = AN standard steel bolt
• Two raised dashes = AN aluminum-alloy bolt

Memory trick: 'Double dash = light aluminum flash'

The time constant (T=RC) determines how quickly a capacitor charges or discharges through a resistor in a series circuit.

• One time constant = 63.2% of full charge
• Capacitor is considered fully charged after about 5 time constants
• T=R×C, measured in seconds
• Larger R or C values result in slower charging

Memory trick: RC is like filling a bathtub — bigger resistance/capacitance means slower fill.

The difference between an aircraft's maximum certificated gross weight and its basic empty weight, representing the weight available for crew, passengers, fuel, and cargo.

• Useful Load = Max Gross Weight − Basic Empty Weight
• Includes usable fuel, oil (if not in BEW), crew, passengers, cargo
• Found on the aircraft's weight and balance report

Memory trick: Useful load = what's left in your suitcase after the plane's own weight.

A hardness test that measures the depth of penetration of an indenter into a material under a fixed major load after a minor preload, with shallower penetration indicating greater hardness.

• Uses a diamond cone or hardened steel ball indenter
• Applies a minor load first, then a major load
• Hardness value is derived from the difference in penetration depth

Memory trick: 'Rockwell digs deep to measure hard' - depth of dent tells the story

Guidelines for selecting cleaning agents that will not chemically attack aircraft metals such as magnesium and aluminum.

• Avoid alkaline/caustic cleaners on Mg/Al alloys
• Use mild pH-neutral soap for general washing
• Apply corrosion inhibitor after drying bare metal areas

Memory trick: Alkaline + Magnesium = angry metal that corrodes fast.

An FAA approval under 14 CFR part 21, Subpart K, authorizing a manufacturer to produce replacement or modification parts for installation on type-certificated products.

• Combines design and production approval in one authorization
• Distinct from TSO, which authorizes standardized appliances/materials
• PMA parts are legally installable without a separate field approval

Memory trick: 'PMA = Pre-approved Manufacturing Authority.'

A change to an aircraft not listed in the manufacturer's specifications that could appreciably affect weight, balance, structural strength, performance, or other qualities affecting airworthiness.

• Requires FAA-approved data.
• Documented on FAA Form 337.
• Contrasts with minor alterations, which don't need such approval.

Memory trick: 'Major moves the needle' — big impact = major alteration.

A location reference measuring lateral distance, in inches, to the left or right of the aircraft's centerline (BL 0), used with FS and WL to locate a point in three dimensions.

• Centerline is BL 0
• Left/Right designations distinguish sides
• Used together with FS and WL for precise 3-D location

Memory trick: BL = 'Beside the Line' — how far sideways from centerline.

A human factor in which real or perceived demands (schedules, customers, management) push a technician to rush or take shortcuts.

• Often driven by schedules, customers, or management
• Can lead to skipped steps or incomplete inspections
• Mitigated by realistic scheduling and empowering technicians to say 'not yet ready'

Memory trick: 'Pressure pushes shortcuts' — deadlines squeeze out safety steps.

After solution heat treatment and quenching, aluminum alloys harden over time (naturally at room temperature or artificially at elevated temperature) as alloying elements precipitate within the grain structure.

• Solution treatment dissolves alloying elements at high temp
• Quenching locks elements in solid solution
• Aging (natural or artificial) precipitates hardening compounds

Memory trick: 'Heat, quench, then quietly harden'

Recurring Airworthiness Directives require documentation of the method of compliance plus the next due date/time.

• 91.417(a)(2)(v) governs AD status recordkeeping
• One-time ADs need only method and date of compliance
• Recurring ADs must show next compliance time to prevent overflight

Memory trick: 'Recurring AD = set the next alarm clock.'

A conductor's resistance depends on its length, cross-sectional area, material type, and temperature.

• Resistance increases with length
• Resistance decreases with larger cross-sectional area
• Different materials have different resistivity
• Most conductors' resistance increases with temperature

Memory trick: LAMT: Length, Area, Material, Temperature — think of a garden hose.

Safe lifting of heavy components requires slings rated above the load weight, attached at approved lift points, with the load kept balanced and centered.

• Sling/hoist rated capacity must exceed actual load weight with safety margin
• Attach only at manufacturer-designated lift points
• Keep load centered and balanced under the hoist to avoid swinging or dropping

Memory trick: Rate it high, hook it right, keep it centered and tight.

Fiber-insert self-locking nuts are limited to lower temperatures (below about 250°F) because the nylon insert degrades, while all-metal self-locking nuts can be used in high-temperature areas such as exhaust systems.

• Fiber insert locknuts: limited to ~250°F max
• All-metal locknuts: suitable for high-temperature areas (engine, exhaust)
• Locking action in all-metal nuts comes from distorted threads, not an insert

Memory trick: 'Nylon melts, metal survives the heat' - choose all-metal near hot exhausts

A view projected onto a plane parallel to an inclined surface to show that surface's true size and shape, which is distorted in standard orthographic views.

• Used for inclined/slanted surfaces
• Plane of projection is parallel to the inclined feature
• Prevents foreshortening error in dimensioning

Memory trick: Auxiliary = 'aux-help' view for slanted surfaces.

Standard torque tables assume a specific thread friction condition; changing lubrication (wet vs. dry) alters the relationship between applied torque and actual bolt preload.

• Torque tables typically assume dry, unlubricated threads
• Lubrication reduces friction, increasing preload for a given torque
• Using the wrong friction assumption can overstress or understress a fastener

Memory trick: Oil the threads, and the bolt squeezes tighter than the chart intended

A method of weighing large aircraft using calibrated jacks and load cells at each designated jack point when platform scales cannot be used under the gear.

• Aircraft is raised until wheels clear the ground
• Aircraft must be leveled at manufacturer's leveling points
• Load cells at each jack point are summed for total weight and CG

Memory trick: Jack it up just enough to float free, then level and read every point.

Work equals force times distance; power is the rate at which work is done, often expressed in horsepower.

• Work = Force × Distance (ft-lb)
• Power = Work ÷ Time (ft-lb/sec)
• 1 horsepower = 550 ft-lb/sec
• Faster work performed for the same task requires greater power

Memory trick: Work is the job, power is how fast you finish it.

A pictorial drawing type with three axes spaced 120° apart, allowing true-to-scale measurement along each axis while presenting a 3-D appearance.

• Axes are 120° apart
• True dimensions along each axis
• Used for parts catalogs and assembly illustrations

Memory trick: Iso-120: three arms spread evenly like a peace sign.

An electrochemical process that forms a protective aluminum oxide layer on aluminum parts to improve corrosion resistance and paint adhesion.

• Produces thin, corrosion-resistant oxide film
• Improves paint/primer adhesion
• Causes less fatigue strength reduction than sulfuric anodizing
• Commonly used on aircraft aluminum structural parts

Memory trick: "Chromic coats to keep corrosion out and paint stuck on."

Mixture ratios such as 20:1 indicate parts of one substance per one part of another; dividing the total volume by the ratio number gives the smaller component's amount.

• Ratio X:1 means X parts of first substance per 1 part second
• Divide total volume of the larger part by the ratio number
• Common in two-stroke oil/fuel mixing and cleaning solutions
• Always confirm units match before dividing

Memory trick: Divide the big number by the ratio to find the little ingredient.

A human factor describing physical, mental, or emotional strain—often from personal life or workplace issues—that degrades performance and decision-making.

• Can be acute (short-term) or chronic (long-term)
• Personal life stress can carry over into the workplace
• Reduces concentration and increases error rate

Memory trick: 'Stress fogs the mind' even without a deadline or lack of sleep.

Each fully charged lead-acid cell produces approximately 2.1 volts open-circuit; cells are connected in series to reach nominal battery voltage.

• 6 cells in series = 12.6V nominal 12V battery
• 12 cells in series = 25.2V nominal 24V battery
• Nominal rating is lower than actual fully charged voltage

Memory trick: Each lead-acid cell adds 2.1V — stack six for a '12-volt' battery that's really 12.6V.

The weight of chocks, blocks, or other items placed on a scale during aircraft weighing that are not part of the aircraft; it must be subtracted from the scale reading.

• Applies to chocks, jack pads, shims on scales
• Subtracted from gross scale reading
• Necessary for accurate net aircraft weight

Memory trick: Tare = 'take away' the extra stuff on the scale.

A repair technique where a small hole is drilled at the tip of a crack to relieve stress concentration and prevent further crack propagation before permanent repair.

• Hole must be centered exactly at the crack tip
• Removes the sharp point where stress concentrates
• Typically a temporary measure until a doubler or patch is installed

Memory trick: 'A round hole rounds off the sharp stress' - drilling stops crack growth

Maintenance practice for correcting electrolyte level and monitoring charge state of lead-acid aircraft batteries.

• Add distilled water only, never acid
• Specific gravity checked with hydrometer
• PPE required due to corrosive electrolyte

Memory trick: Water leaves, acid stays — refill with distilled water only.

Standardized hand/arm signals used by ground crew to direct aircraft movement during taxi, towing, and pushback.

• Crossed arms overhead = emergency stop
• Normal stop = arms extended, brought together slowly
• Signals must be visible and unambiguous at all times

Memory trick: Arms crossed like an X = eXtreme stop now!

N-type silicon is produced by adding a pentavalent (5 valence electron) impurity, which supplies extra free electrons as majority charge carriers.

• Pentavalent dopants: phosphorus, arsenic, antimony
• Extra electron becomes a free carrier
• N-type carriers are electrons (negative)

Memory trick: 'N for Negative, Need 5' - N-type needs 5-valence dopants for extra electrons.

14 CFR 91.203 requires an aircraft to carry an effective Certificate of Registration and display a valid Airworthiness Certificate before flight; remember with the mnemonic ARROW (Airworthiness, Registration, Radio license, Operating limitations, Weight and balance).

• Airworthiness Certificate displayed at cabin/cockpit entrance
• Registration Certificate must be carried aboard
• Radio station license required for international flights
• Operating limitations and weight/balance data also required aboard

Memory trick: ARROW points the way: Airworthiness, Registration, Radio license, Operating limitations, Weight & balance.

Ductility is a metal's ability to be stretched into wire under tension; malleability is its ability to be hammered or rolled into sheets under compression.

• Ductility = tensile deformation (wire drawing)
• Malleability = compressive deformation (rolling/hammering)
• Elasticity = returns to original shape after load removed
• Hardness = resistance to indentation

Memory trick: "Ductile = drawn into wire; Malleable = mashed into sheet."

Specifies which maintenance records must be kept and for how long by the aircraft owner/operator.

• Routine maintenance records: 1 year or until superseded
• AD compliance/life-limited part status: retained until superseded or part replaced
• Total time in service: retained for the life of the aircraft

Memory trick: 'Total time travels with the plane forever.'

A joining process using a nonferrous filler metal with a melting point above 800°F but below that of the base metal, bonded by capillary attraction.

• Filler melts >800°F but below base metal melting point
• Base metal is not melted
• Common fillers include silver and brass alloys

Memory trick: Solder low, Braze in-between, Weld melts the metal

The algebraic sum of currents entering a junction equals the sum of currents leaving it, based on conservation of electric charge.

• Also called the junction rule
• Total current in = total current out
• Fundamental to analyzing parallel and combined circuits

Memory trick: 'What flows in must flow out' - no charge is lost at a junction.

Relates internal pressure, tube wall thickness, tensile strength, and diameter: P = 2tS/D, used to estimate burst pressure of tubing under internal pressure.

• P = 2tS/D (P=burst pressure, t=wall thickness, S=tensile strength, D=diameter)
• Thicker walls and higher tensile strength increase burst pressure
• Larger diameter decreases burst pressure for the same wall thickness

Memory trick: 'Two times thickness times strength, over diameter' bursts the tube.

For incompressible fluid flow, the product of cross-sectional area and velocity is constant along a line: A1V1 = A2V2.

• Flow rate (volume/time) stays constant
• Smaller area = higher velocity
• Larger area = lower velocity

Memory trick: 'Squeeze the hose, water shoots faster' — smaller area, higher speed.

When a major alteration is accomplished under a Supplemental Type Certificate, the FAA Form 337 must reference the specific STC number and its approved data as the basis of approval.

• STC provides pre-approved engineering data for a specific modification
• Form 337 documents the major alteration and cites the STC number
• Aircraft records/equipment list must be updated after installation
• Using an STC avoids the need for a separate field approval

Memory trick: The STC number on Form 337 is the alteration's birth certificate—it proves FAA approval already exists.

The volume of a cylinder equals π times the radius squared times the height (V = πr²h), and can be rearranged to solve for any unknown variable.

• V = πr²h
• Solve for h: h = V ÷ (πr²)
• Solve for r: r = √(V ÷ (πh))

Memory trick: Volume equals pi times radius squared times height — rearrange to isolate the mystery.

P-type material is created by adding trivalent impurity atoms (3 valence electrons) to pure silicon, creating electron-deficient holes as majority carriers.

• Trivalent dopants: e.g., boron, gallium, indium
• Holes act as positive majority charge carriers
• Opposite is N-type, made with pentavalent dopants like arsenic

Memory trick: P for 'Positive holes' — three electrons leaves a gap to fill.