FAA Aviation Mechanic General (AMG) flashcards

Simple, low-risk maintenance tasks a certificated pilot may legally perform on an aircraft they own or operate.

• Listed items include replacing safety belts, servicing wheel bearings, and changing tires.
• Pilot must be the owner/operator to use this privilege.
• Entries must still be made in the aircraft records per 43.9.

Memory trick: 'Pilots Patch Simple Stuff' — small fixes only.

Aircraft tires are inflated with dry nitrogen rather than compressed air to reduce fire/explosion risk and internal oxidation.

• Nitrogen is inert and moisture-free
• Prevents oxidation-related tire degradation
• Pressure checked when tire is cold for accuracy

Memory trick: Nitrogen = 'No oxidation, No moisture' for safer tires.

Capacitance depends on plate area, distance between plates, and the dielectric constant of the insulating material.

• Capacitance increases with larger plate area
• Capacitance decreases with greater plate spacing
• Higher dielectric constant increases capacitance
• Measured in farads

Memory trick: Big plates, close together, good insulator = big capacitance.

Securing an aircraft to ground anchors using ropes at roughly 45-degree angles to resist wind-induced lift and lateral forces.

• Ropes typically run from wing, tail, and nose tie-down rings
• 45-degree angle balances vertical and horizontal restraint
• Chocks and control locks also used in conjunction with tie-downs

Memory trick: 45 degrees splits the difference between up and sideways.

Specifies the minimum information required in a logbook entry for maintenance, preventive maintenance, rebuilding, and alteration.

• Requires description of work, date, and who performed it
• Requires signature, certificate number, and kind of certificate of approving person
• Total time in service is a separate 43.11 inspection requirement

Memory trick: 'DDSK' — Description, Date, Signature, Kind of certificate.

A way of expressing CG location relative to the mean aerodynamic chord, calculated as [(CG station − LEMAC)/MAC length] × 100, commonly used on transport category aircraft loading limits.

• LEMAC = leading edge of MAC station
• Formula: %MAC = (CG−LEMAC)/MAC length × 100
• Used to check CG against aft/forward %MAC limits on many airliners

Memory trick: Subtract LEMAC, divide by chord length, multiply by 100 — 'SLIM' the CG into a percentage.

Establishes the required methods, techniques, and practices for performing maintenance, and mandates use of proper tools and equipment.

• Primary source: manufacturer's manual or ICA
• Alternate source: methods acceptable to the Administrator
• Work must result in a condition at least equal to original design

Memory trick: 'Manual first, Administrator as backup.'

Aircraft control cables are classified by strand and wire count, which determines flexibility; more wires per strand means greater flexibility.

• 7x19 (133 wires) = most flexible, used for control cables
• 7x7 (49 wires) = moderate flexibility, used for trim/tab cables
• 1x19 (19 wires) = solid/rigid, used for standing rigging

Memory trick: 'Nineteen times seven wires makes it flex like heaven' - more strands, more bends

A lever or scale is balanced when the moments (weight × distance) on both sides of the fulcrum are equal.

• Moment = Force (or weight) × Distance from fulcrum
• Balance condition: W1 × D1 = W2 × D2
• Used in aircraft weight and balance calculations

Memory trick: 'Equal moments keep the see-saw level' — weight times distance must match.

For active-mode amplification, an NPN transistor's base-emitter junction must be forward biased while the base-collector junction is reverse biased.

• NPN = layers Negative-Positive-Negative
• Forward bias on base-emitter allows base current
• Reverse bias on base-collector allows amplified collector current

Memory trick: 'Forward the Base-Emitter, Reverse the Collector' for active amplification.

The relationship used to determine the output force of a hydraulic or pneumatic piston based on system pressure and piston area.

• F = P × A
• Pressure is measured in psi (lb/in²)
• Area must be in square inches for the formula to work directly
• Used to size actuators and cylinders in hydraulic systems

Memory trick: Pressure pushes on area to create force — PA equals Force.

A method of safety-wiring turnbuckles where wire is wrapped at least twice around each terminal end to prevent the barrel from rotating and loosening the cable tension.

• Minimum of 2 wraps around each terminal required
• Alternative methods include single-wrap and clip-locking pin
• Purpose is to prevent turnbuckle barrel rotation in flight

Memory trick: 'Double wrap, double security' - wrap twice around each end

A pin that disconnects the nose gear steering actuator so the wheel can be turned by a tow bar without damaging internal steering components.

• Must be installed/pulled per aircraft-specific procedure before towing
• Prevents damage to steering actuator/gearbox
• Shear pins in tow bars protect against excessive torque, a separate function

Memory trick: Pin it, then tow it — protect the nose before you go.

The ratio of the density (or weight) of a substance to the density of water at the same temperature.

• Specific gravity = substance weight ÷ water weight
• Water has a specific gravity of 1.0
• Values below 1.0 indicate the substance is lighter than water

Memory trick: Compare everything to water's baseline of 1.0.

When an aircraft is sold, 14 CFR 91.417 requires that records of total time in service and current AD compliance status be transferred with the aircraft to the new owner.

• Total time in service records are retained permanently and transferred
• Current AD status must accompany the aircraft
• Routine maintenance records need only be retained 1 year unless superseded
• Missing transferred records can complicate airworthiness verification

Memory trick: The logbook rides along with the plane—total time and ADs never get left behind.

A simple nondestructive inspection method for composite honeycomb structures where tapping the surface and listening for a change in sound reveals internal delamination or disbonding.

• A 'dead' or dull sound indicates a possible disbond
• Requires no special equipment, just a coin or small hammer
• Not effective for locating small or deep defects; supplemented by ultrasonic inspection

Memory trick: 'Tap it and listen — a dull thud means trouble'

Hydrocarbon-based oils and greases must never contact oxygen system components due to violent, spontaneous combustion risk under high-pressure oxygen.

• Only oxygen-approved, non-hydrocarbon lubricants (often silicone-based) are permitted
• Oil/grease contamination can cause explosion or fire in oxygen lines/fittings
• Technicians must keep hands, tools, and fittings free of oil/grease during servicing

Memory trick: Oil plus oxygen equals ignition — keep it clean and approved.

One of the twelve human factors that lead to maintenance errors; occurs when a technician lacks the training, data, or experience required to perform a task correctly.

• Mitigated by proper training and current technical data
• Different materials/systems require specific procedures
• Never assume old techniques apply to new technology

Memory trick: 'Know before you go' — never guess on unfamiliar systems.

To calculate ballast needed to move CG to a target location, use: Weight to add = [Total weight × (Actual CG − Desired CG)] ÷ (Desired CG − Arm of added weight).

• Used when CG is out of limits and ballast must be added
• Arm of added weight must be forward of desired CG to move CG forward
• Formula rearranges the weighted-average moment concept

Memory trick: Add weight far from CG for maximum leverage effect

A cotter pin inserted through a drilled bolt and a castellated nut prevents the nut from rotating loose under vibration.

• Requires a castellated (slotted) nut and drilled bolt
• One prong bent over the bolt end, other along the nut flat
• Never reuse a bent/removed cotter pin

Memory trick: 'Pin it so it can't spin it'

A mechanic must have been actively engaged in maintaining aircraft for at least 6 months of the preceding 24 months, or otherwise satisfy the FAA Administrator of competency, before exercising certificate privileges.

• Mechanic certificates themselves do not expire
• Recency requirement is 6 of the preceding 24 months
• Competency can also be shown by other means acceptable to the FAA
• Failure to meet this bars exercising certificate privileges until satisfied

Memory trick: '6 out of 24' keeps your wrench-turning rights alive.

A basic rate formula relating speed, distance, and time, commonly used in navigation and performance calculations.

• Speed = Distance ÷ Time
• Distance = Speed × Time
• Time = Distance ÷ Speed
• Nautical miles per hour equals knots

Memory trick: Distance over time gives you speed every time.

The cross-sectional area inside a tube available for fluid flow, based on the inside diameter, not the outside diameter.

• ID = OD − 2(wall thickness)
• Area = πr²
• Wall thickness reduces usable flow area

Memory trick: Subtract both walls before you square the radius.

A ratio comparing the size of a feature on a drawing to its actual size on the part; 1:2 means the drawing is half the actual size.

• 1:1 is full scale (drawing = actual size)
• 1:2 means drawing is half size, so actual = drawing measurement × 2
• 2:1 means drawing is enlarged (twice actual size)

Memory trick: First number is the drawing, second is the real part — 1:2 means drawing is small, part is big.

The process of positioning an aircraft so it is level both longitudinally and laterally, using a plumb bob or spirit level at manufacturer-specified points, to ensure accurate weight and balance data.

• Leveling establishes a true horizontal reference for arm measurements
• Manufacturer specifies leveling points and method (plumb bob or level)
• Must be done before recording scale readings for W&B

Memory trick: Level it first, or every arm measurement afterward is a lie

A lever multiplies force based on the ratio of the effort arm length to the resistance arm length.

• MA = effort arm ÷ resistance arm
• Resistance force = effort force × MA
• Longer effort arm relative to resistance arm increases force multiplication

Memory trick: Longer effort arm, bigger payoff on the short side.

Power in a DC circuit equals current multiplied by voltage (P=IE), measured in watts.

• P=I×E
• Also P=I²R or P=E²/R
• Watt is the unit of power
• Power indicates rate of energy use

Memory trick: Power is what lights the bulb — multiply the push (E) by the flow (I).

Density relates weight to volume: Weight = Density × Volume, commonly used to determine fluid weight in a container.

• Density is typically given in lb/in³ or lb/gal for fluids
• Weight = Density × Volume
• Density can be converted between units (lb/in³, lb/ft³, lb/gal)

Memory trick: 'Pack it in, weigh it out' — density times volume tells you the load.

A simple machine where MA equals the ratio of the slope length to its vertical rise, allowing a smaller force to move a load over a longer distance.

• MA = length of incline / height of incline
• Longer, shallower ramps give greater mechanical advantage
• Trade-off: less force but greater distance traveled

Memory trick: 'Long ramp, light load' — length over height gives the advantage.

A circuit containing both series and parallel resistor combinations, requiring stepwise reduction to find total resistance.

• Reduce parallel sections to equivalent resistance first
• Add series resistances to the parallel equivalent
• Apply Ohm's Law to the total resistance for total current

Memory trick: Combine like puzzle pieces — parallel first, then add the series piece.

Converting millimeter measurements to inches by dividing by the conversion factor 25.4 mm per inch.

• 1 inch = 25.4 mm exactly
• Divide mm by 25.4 to get inches
• Multiply inches by 25.4 to get mm

Memory trick: '25.4 is the magic gate' between inches and millimeters.

On the rod side of a double-acting actuator, the effective area is reduced by the rod's cross-sectional area, resulting in less force than the blind side for the same pressure.

• Effective rod-side area = Bore area − Rod area
• Force = Pressure × Effective Area
• Retract force is typically less than extend force at the same pressure due to reduced area

Memory trick: 'Rod steals some square inches' — subtract it before multiplying by pressure.

Subsurface corrosion that follows grain boundaries in extruded or rolled aluminum, causing the surface to lift and delaminate in layers.

• Follows grain flow direction in extrusions/forgings
• Surface swells and separates like pages of a book
• Common in high-strength 2xxx and 7xxx aluminum alloys

Memory trick: Exfoliation peels like the pages of an old book

A drafting method that shows an object in two or more separate views (front, top, side), each true to scale, to fully describe its shape and dimensions.

• Standard views: front, top, side (right side)
• Each view shows true shape/size with no distortion
• Used for detailed manufacturing drawings

Memory trick: 'Ortho' = straight-on, three honest views tell the whole truth

To prevent tube damage such as flattening, wrinkling, or wall thinning, tubing must be bent no tighter than a minimum radius, typically about 3 times the tube's outside diameter.

• Minimum bend radius ≈ 3 × tube OD (general guidance)
• Bending tighter causes wall thinning and possible cracking
• Applies to aluminum alloy tubing used in fluid line fabrication

Memory trick: 'Three times the tube, keep it smooth' — never bend tighter than 3×OD.

A balanced oxygen-to-acetylene flame with a sharply defined, rounded inner cone and no feather, used for most aircraft steel welding to avoid carburizing or oxidizing the weld.

• Identified by a clear, well-defined inner cone
• Balanced mixture of oxygen and acetylene gas
• Preferred flame setting for most ferrous metal aircraft welding

Memory trick: 'Neutral keeps it balanced, no feather, no fuss' - the safe welding flame

The ratio of total cylinder volume (piston at bottom) to clearance volume (piston at top), indicating how much the fuel-air mixture is compressed.

• CR = Total volume ÷ Clearance volume
• Higher CR generally increases engine efficiency and power
• Excessive CR can cause detonation without proper fuel

Memory trick: 'Big volume squeezed into small volume' gives the ratio.

Force equals mass times acceleration; in English units, mass is measured in slugs (weight in pounds divided by 32.2 ft/s²).

• Mass (slugs) = Weight (lb) / 32.2 ft/s²
• Force (lb) = mass (slugs) × acceleration (ft/s²)
• Do not confuse weight (a force) with mass in calculations

Memory trick: 'Slugs push, pounds pull' — always convert weight to mass before F=ma.

The opposition a capacitor presents to AC current flow, which decreases as frequency or capacitance increases.

• Formula: Xc = 1/(2πfC)
• Inversely proportional to frequency and capacitance
• Measured in ohms

Memory trick: Capacitors 'open up' to higher frequencies — Xc shrinks as f and C grow.

Converting a fraction to a decimal by dividing the numerator by the denominator, essential for measuring and matching tubing/fastener sizes.

• Divide numerator by denominator
• 3/8 = 0.375
• Common aviation sizes: 1/4=0.250, 3/8=0.375, 1/2=0.500

Memory trick: Top divided by bottom gives the decimal truth.

Electrical connection between fueling equipment and aircraft that equalizes static charge to prevent sparks during refueling.

• Bonding cable connected before opening fuel caps or nozzles
• Static electricity builds from fuel flow friction
• Bonding must remain connected throughout the fueling operation

Memory trick: Bond before you pour to avoid a spark-fueled roar.

An imaginary vertical plane or line from which all horizontal distances (arms) are measured for weight and balance computations; its location is arbitrary and set by the manufacturer.

• Location varies by aircraft model, often nose, firewall, or a point ahead of the aircraft
• Fixed reference—does not move with loading
• All arms are measured forward (negative) or aft (positive) of the datum per convention

Memory trick: Datum = the 'starting line' manufacturer picks for measuring arms

Procedure for placing wheel chocks to prevent aircraft rollaway when parked on an inclined surface.

• Downhill side chocked first for immediate restraint
• Uphill side chocked second for full security
• Chocks must seat snugly against tires

Memory trick: Downhill first stops the runaway before it starts.

Safety wire mechanically prevents fastener rotation by being installed taut, with proper twist density, routed so loosening motion tightens the wire.

• 6-8 twists per inch for standard 0.032 in wire
• Wire must be in tension, not slack
• End must be bent into a pigtail away from sharp edges

Memory trick: 'Loosen tries to escape, wire drags it back'

Aircraft hydraulic systems require specific fluid types; mixing incompatible types damages seals and can cause system failure.

• MIL-PRF-5606 is mineral-based (red)
• Skydrol is phosphate ester-based (purple), fire-resistant
• Mixing incompatible fluids swells/deteriorates seals

Memory trick: Purple Skydrol hates rubber not made for it.

A specified range of CG locations, published for many small aircraft, within which the empty weight CG must fall to guarantee the loaded CG stays within limits across all approved loading conditions.

• Published in the TCDS or aircraft flight manual for some aircraft
• If empty weight CG falls outside range, corrective action is mandatory
• Prevents out-of-limit loaded CG under standard loading arrangements

Memory trick: Empty weight CG range is the 'safety zone' guaranteeing every load stays legal.

Pressure applied to an enclosed fluid is transmitted undiminished in all directions, allowing hydraulic systems to multiply force.

• Pressure = Force ÷ Area
• Force = Pressure × Area
• Small piston force can be multiplied at a larger piston

Memory trick: Small push, big shove — fluid spreads the load.

Requires a test flight by a qualified pilot before carrying passengers after maintenance that could appreciably affect flight characteristics.

• Applies to repairs/alterations affecting flight characteristics or operation
• Pilot must hold at least a private pilot certificate
• An appropriate log entry documenting the check flight is required

Memory trick: 'Fly it first, fill it with passengers second.'

The standard flare angle used on aircraft AN fluid line fittings to ensure a proper leak-free seal.

• AN fittings use a 37° flare
• Automotive/45° flares are incompatible with AN fittings
• Flared fittings rely on a metal-to-metal seal

Memory trick: AN = 'A Narrow' 37° cone for a tight aircraft seal.

A nondestructive test method that magnetizes a ferromagnetic part and applies fine iron particles to reveal surface and near-surface cracks where the particles cluster at flux leakage points.

• Only works on ferromagnetic materials (steel, iron, some nickel alloys)
• Cracks perpendicular to the magnetic field are most detectable
• Part must be demagnetized after inspection

Memory trick: 'Magnets grab iron dust at every crack' - MPI needs ferromagnetic metal

A chart or table defining the forward and aft CG limits for a given aircraft weight; the loaded CG must fall within these limits for safe flight.

• CG = Total Moment ÷ Total Weight
• Must fall between forward and aft limits for that weight
• Limits can vary with total weight (envelope shape)

Memory trick: CG envelope = the safe 'lane' the CG must stay inside.

An organic cotton fabric historically used for aircraft covering, meeting minimum tensile strength standards but more susceptible to mildew, rot, and shorter service life than modern synthetic fabrics.

• Organic fiber, prone to mildew and rot
• Shorter service life than polyester (Ceconite-type) fabric
• Still requires dope finishing system for protection and tautness

Memory trick: Cotton is organic — it can rot like an old cotton shirt in the rain

An aluminum-silicon alloy filler rod commonly used for TIG/gas welding of aluminum aircraft structures due to good flow and crack resistance.

• 4043 contains ~5% silicon for better fluidity
• Reduces weld cracking compared to pure aluminum rod
• Widely used on 6061 and similar aluminum alloys
• Steel and nickel rods are not compatible with aluminum base metal

Memory trick: "Forty-forty-three flows free for aluminum repairs."

Defines who may legally approve aircraft, engines, and appliances for return to service after maintenance.

• Major repairs/alterations require IA, repair station, or manufacturer approval
• A&P mechanics may approve minor repairs and preventive maintenance
• IA is an added rating beyond basic A&P certification

Memory trick: 'Major needs the Major League' — only IA/repair station/manufacturer can sign off major work.

The heat energy required to change a material's temperature is found using Q = mass × specific heat × temperature change.

• Q = m × c × ΔT
• Specific heat (c) is unique to each material, measured in BTU/lb°F
• ΔT must be the actual temperature change, not the final temperature alone

Memory trick: 'Mass meets heat capacity times the change' to find the BTU total.

When an extension is used with a torque wrench, the wrench reading must be adjusted to achieve the correct actual torque at the fastener.

• TW = TA × L/(L+A)
• L = wrench length, A = extension length
• Extensions increase leverage, so wrench reading must be lower than actual torque desired

Memory trick: Longer arm, lighter squeeze needed on the dial.

The speed of meshing gears is inversely proportional to their number of teeth; a smaller gear turns faster than a larger one.

• Driven rpm = Drive rpm × (Drive teeth/Driven teeth)
• More teeth = slower rotation, more torque
• Fewer teeth = faster rotation, less torque
• Used in gearboxes, accessory drives, and reduction gearing

Memory trick: Small gear spins fast, big gear spins slow — teeth trade speed for torque.

AN and MS aircraft bolts use a Class 3 (close-tolerance) thread fit for greater precision and strength compared to commercial Class 2 fasteners.

• Class 3 = close fit, tighter tolerances than commercial hardware
• Commercial bolts commonly use Class 2 (free fit)
• Tighter thread fits reduce play and increase fatigue resistance

Memory trick: 'Aircraft bolts get the tightest hug' - Class 3 close fit for precision

When a known weight is moved a known distance within an aircraft, the resulting CG shift equals (weight moved × distance moved) ÷ total aircraft weight.

• CG shift direction matches the direction the weight was moved
• Formula: ΔCG = (weight moved × distance moved) ÷ total weight
• Used for balancing aircraft after cargo relocation

Memory trick: Shift weight, shift CG — same direction, proportionally smaller

A human factors model describing interactions between Software (procedures/manuals), Hardware (equipment/tools), Environment (physical/organizational surroundings), and Liveware (people), centered on the individual (Liveware) at the core.

• Software = procedures, manuals, checklists, computer programs
• Hardware = tools, equipment, physical aircraft components
• Environment = physical, organizational, and social surroundings
• Liveware = the central human element interacting with all others

Memory trick: SHEL: Software, Hardware, Environment, Liveware—people at the center, everything else fits around them like puzzle pieces.