FAA Aviation Mechanic Airframe (AMA) flashcards

A simple nondestructive inspection method using a coin or tap hammer to detect disbonds/delaminations in composite honeycomb structures by listening for changes in sound.

• Sharp, clear ring indicates good bond
• Dull, dead sound indicates disbond or delamination
• Common for quick field checks of sandwich composite structures

Memory trick: 'Dull thud means the sandwich has gone bad (disbonded).'

A two-piece high-strength fastener with a threaded pin and a collar that is torqued until its wrenching flats shear off at a set torque, ensuring proper preload.

• Threaded pin plus collar design
• Collar wrenching flats break away at set torque
• Lighter weight alternative to standard structural bolts

Memory trick: Hi-Lok = collar Locks by breaking off at the right torque.

A fastener riveted permanently to structure that provides internal threads so a screw can be installed and removed from the outside.

• Commonly used on removable access panels and fairings
• Prevents loose nuts from falling inside the structure
• Comes in floating and fixed designs

Memory trick: Nutplate = the nut that never leaves home

A test required under 14 CFR Part 43 Appendix E to verify the airtightness of the pitot-static system by monitoring altimeter indication decay after applying vacuum.

• Applies to altimeter/static system tests every 24 calendar months
• Unpressurized aircraft: max 100 ft loss in 1 minute
• Test is part of the required altimeter and static system inspection

Memory trick: 100 feet, 1 minute — the century mark for a tight static system.

A mechanical system in vacuum-driven attitude indicators using gravity-controlled vanes at the air exhaust ports to correct gyro precession and maintain vertical alignment.

• Vanes hang under gravity and shift with gyro tilt
• Unequal air exhaust creates a correcting precession torque
• Continuously erects the gyro to true vertical during normal flight

Memory trick: Pendulous vanes swing like tiny weights steering the airflow to keep the gyro upright

A hydraulic actuator with ports on both sides of the piston, allowing fluid pressure to extend and retract the piston.

• Contrasts with single-acting actuators (fluid one direction only)
• Common in landing gear, flight control actuators
• Requires selector valve to direct fluid to each side

Memory trick: Double-acting pushes both ways, like a two-way door.

Wavy ripples or buckling in aircraft skin, especially near spars or ribs, that can indicate internal structural deformation from overstress events like hard landings; requires further structural investigation.

• Often found near primary structure attach points
• Requires inspection per manufacturer hard-landing/overstress procedures
• May require spar/rib inspection, NDT, or disassembly to assess extent

Memory trick: Wrinkles ripple from bent bones (spar/rib) beneath

A safety device in a wheel hub containing a low-melting alloy that melts at a set temperature to deflate the tire and prevent explosive failure from brake overheating.

• Melts at a specific predetermined temperature
• Prevents explosive tire/wheel failure from brake heat
• Located in the wheel hub near the brake side

Memory trick: 'Fuse it before it blows' - the fusible plug sacrifices itself to save the wheel

A bleed-air cooling system that compresses, cools, and then expands air through a turbine to produce cold air for cabin air conditioning.

• Uses bleed air as its source
• Turbine expansion extracts energy causing a large temperature drop
• Turbine also drives the compressor and cooling fan

Memory trick: Spinning the turbine sucks the heat right out of the air, like a fan blowing away warmth.

A brittle line of paint applied across a fastener head and adjacent structure after proper torquing, used as a quick visual check to detect fastener loosening or rotation.

• Applied only after fastener is torqued to specification
• A broken/misaligned stripe indicates possible loosening
• Common on critical fasteners in flight controls, engine mounts, landing gear

Memory trick: Torque stripe breaks = bolt has 'walked'

A safety device that senses abnormally high flow (as from a broken line) and shuts off fluid flow to prevent total system fluid loss.

• Responds to excessive flow rate, not pressure
• Protects against total fluid loss from line rupture
• Common in landing gear, flap, and brake lines

Memory trick: A fuse blows when flow floods too fast.

An ammeter arrangement using a precision low-resistance shunt in series with the load so the meter measures a proportional voltage drop instead of carrying full circuit current.

• Shunt carries nearly all the load current
• Meter measures millivolt drop across shunt
• Allows accurate measurement of high currents without oversized meter movements

Memory trick: Shunt shares the load so the meter stays small.

A line that routes internal leakage fluid from within a variable-displacement pump housing back to the reservoir, used to cool and lubricate the pump and serving as a wear-monitoring point.

• Internal leakage normally cools/lubricates pump components
• Case drain flow rate is compared to manufacturer specifications
• Excessive flow indicates worn pistons, cylinder bores, or seals

Memory trick: Case drain = the pump's 'blood test' — too much flow means internal wear.

A special inspection performed after a reported hard or overweight landing to check load-bearing structures for hidden damage beyond normal wear.

• Focuses on landing gear, attach fittings, wing spar, and firewall
• Required by manufacturer maintenance manual guidance
• May include measuring for wrinkles, cracks, or shifted rivets

Memory trick: 'Hard landing hits the Gear, Spar, and Firewall hardest.'

When switching to an alternate static source venting into an unpressurized cabin, the pitot-static instruments may show erroneous readings due to differences between cabin and true outside static pressure.

• Cabin static pressure is often lower than outside ambient due to airflow (Bernoulli effect)
• Lower static pressure causes altimeter to read higher than actual
• Airspeed indicator typically reads higher than actual with alternate static source
• Correction values are usually published in the aircraft flight manual (AFM)

Memory trick: Lower pressure inside the cabin tricks the altimeter into thinking you're higher — like a balloon expanding at altitude.

The formula BA = (0.01743R + 0.0078T) x N calculates the amount of material needed for a bend in sheet metal, based on radius, thickness, and bend angle.

• R = bend radius, T = material thickness, N = bend angle in degrees
• Used to determine flat-pattern layout dimensions
• Found in FAA AC 43.13-1B, Chapter 4

Memory trick: 'Radius and Thickness, times the angle, gives the stretch.'

A structural design philosophy using multiple redundant load paths so that failure of one member does not cause overall structural failure, allowing continued safe flight until detected.

• Uses redundant load paths (multiple spars, stringers, etc.)
• Failure of one member is tolerated
• Different from safe-life (retirement) and damage-tolerant (inspection-based crack monitoring) philosophies

Memory trick: Fail-Safe = if one path Fails, others stay Safe.

Hydraulic filter elements are generally either disposable micronic (paper/fiber, fine filtration, replace only) or cleanable wire mesh (metal, reusable, coarser filtration).

• Micronic elements offer finer filtration but cannot be cleaned
• Wire mesh elements are durable and can be ultrasonically cleaned
• Element choice affects both contamination control and maintenance cost

Memory trick: Paper is 'pitched' (disposable); mesh is 'mended' (cleanable)

Total resistance in a parallel circuit is always less than the smallest individual resistor and is found using the product-over-sum (for two resistors) or reciprocal method.

• Total R is always less than smallest branch resistor
• Two-resistor formula: Rt = (R1×R2)/(R1+R2)
• Multi-resistor formula: 1/Rt = 1/R1 + 1/R2 + ...
• Voltage is the same across all parallel branches

Memory trick: More lanes on the highway means less traffic resistance overall — adding parallel paths always lowers total resistance.

A valve that regulates bleed air pressure and controls on/off flow to the wing leading edge piccolo tube anti-ice system; failure to close can cause overheat damage.

• Controls both pressure and shutoff of hot bleed air
• Located upstream of the piccolo tube distribution system
• Failure to close risks leading edge skin overheat/damage

Memory trick: Stuck-open valve = leading edge left in a sauna.

The form used to record and report major repairs and alterations performed on an aircraft, engine, propeller, or appliance, per Part 43 Appendix B.

• Required for major repairs/alterations, not minor ones
• Copy given to aircraft owner
• Copy generally submitted to FAA within 48 hours if returned to service
• Becomes a permanent maintenance record

Memory trick: '337' sounds like 'DIY' major fix paperwork you must file

A non-electrolytic chemical treatment applied to bare aluminum that forms a thin protective, corrosion-resistant film and improves paint adhesion.

• Produces gold/yellow iridescent finish
• No electric current required
• Applied before priming and painting

Memory trick: Alodine = A liquid dip, no electricity needed.

Standardized markings stamped on AN bolt heads that identify the bolt's material and specification.

• Single raised dash = AN standard steel bolt
• Cross/X = corrosion-resistant steel bolt
• Two raised dashes = aluminum alloy bolt
• Asterisk or recessed triangle = NAS close-tolerance bolt

Memory trick: 'One dash, one common steel bolt.'

Checking tire inflation pressure before the tire has been heated by operation or ambient sun, ensuring an accurate reading against manufacturer specifications.

• Heat from taxi/flight raises pressure readings falsely high
• Check before first flight or after sufficient cool-down
• Use manufacturer's cold inflation pressure chart
• Under-inflation causes shoulder wear, over-inflation causes center wear

Memory trick: Cold and calm gives the true tire exam.

A mechanical device between an engine and AC generator that maintains a constant generator shaft speed despite engine RPM variations, ensuring stable output frequency.

• Frequency formula: f = (P × RPM) / 120
• Keeps generator speed constant for stable 400 Hz output
• Failure of the CSD causes frequency to vary with engine RPM

Memory trick: CSD = 'Constant Spin, Dependable frequency' no matter the engine's mood.

An electromagnetic device consisting of a transmitter and receiver, each with rotor and stator windings, used to transmit angular position information remotely without mechanical linkage.

• Used in fuel quantity, flap position, and control surface indicators
• Transmitter rotor position induces corresponding voltages in receiver stator
• Receiver rotor aligns to match transmitter rotor angle
• No mechanical connection required between transmitter and indicator

Memory trick: Think of two dancers mirroring each other's moves across a room without touching — that's the synchro's electromagnetic mirroring.

An electrical instrument that senses local airflow angle via a vane or differential pressure probe and displays angle of attack, providing a stall margin independent of weight, altitude, or bank angle.

• Critical AOA at stall is constant regardless of weight or bank angle
• Sensor may be a vane-type or differential pressure probe
• Signal is transmitted electrically to a cockpit indicator or display

Memory trick: Angle, not airspeed, tells the wing when it's about to quit.

Critical maintenance items designated in an air carrier's maintenance program that require an independent inspection by someone other than the person who performed the work.

• Applies to parts 121 and 135 operations
• Ensures an independent check on flight-critical maintenance
• Inspector must be specifically authorized/qualified for RII duties

Memory trick: RII = a 'second set of eyes' checking critical work

A system that uses an air separation module to produce nitrogen-enriched air, which is injected into fuel tank ullage to reduce oxygen concentration and fire risk.

• Uses bleed air through an air separation module (ASM)
• Produces nitrogen-enriched air (NEA)
• Lowers oxygen content below flammability threshold in fuel tank ullage

Memory trick: OBIGGS suffocates the fire before it can even start, by starving it of oxygen.

A fuel quantity indicating system that measures capacitance between tank probes, which changes as fuel (a different dielectric than air) rises or falls between the plates.

• Probes act as a capacitor with fuel/air as dielectric
• Capacitance increases as fuel level rises
• Indicating circuit converts capacitance change to a quantity reading

Memory trick: Fuel fills the gap like a bigger dielectric raising capacitance

A fan in the environmental control system that recirculates filtered cabin air, mixing it with fresh bleed air to reduce bleed air demand.

• Improves fuel efficiency by reducing bleed air extraction
• Air passes through HEPA filters before recirculation
• Works alongside the air cycle machine pack for cabin conditioning

Memory trick: Recirc fan recycles cabin air like a home HVAC return duct.

An instrument that computes and displays Mach number using the ratio of impact pressure (pitot minus static) to absolute static pressure.

• Combines an altitude aneroid and a differential pressure capsule
• Ratio of impact pressure to static pressure yields Mach number
• Static pressure correlates with local speed of sound at altitude

Memory trick: Mach = impact pressure riding on the back of static pressure.

Electrical bonding between fueling equipment and the aircraft equalizes electrical potential to prevent static discharge sparks during refueling.

• Prevents ignition of fuel vapors from static discharge
• Required before opening fuel caps or connecting hoses
• Aircraft and fuel truck are also grounded to earth ground

Memory trick: Bond before you pour—no spark near the vapor.

A flexible, synthetic rubber fuel tank liner installed inside a wing or fuselage bay structure that holds fuel without being load-bearing.

• Made of synthetic rubber-coated fabric
• Minor wrinkles are normal within manufacturer limits
• Supported by the surrounding structural cavity, not self-supporting

Memory trick: Bladders bend, wrinkles are friends (within limits).

A fuselage design in which the skin, longitudinal stringers/longerons, and transverse frames/bulkheads all share structural loads, unlike monocoque construction where the skin alone carries the load.

• Stringers/longerons run fore-and-aft, resisting bending loads
• Frames/bulkheads run circumferentially, maintaining shape
• Most modern aircraft fuselages use semi-monocoque construction

Memory trick: 'Stringers run the length, Frames hug the round' — longitudinal vs transverse.

An electrochemical surface treatment in which an aluminum part serves as the anode in an electrolytic bath (chromic or sulfuric acid), building up a hard, corrosion-resistant oxide layer that also improves paint adhesion.

• Part is made the anode; current passes through an acid electrolyte bath.
• Chromic acid anodizing is common on aircraft structural aluminum parts.
• Produces a harder, more durable oxide layer than chemical conversion coatings like Alodine.

Memory trick: Anodizing = 'Anode' + 'Oxide' building up under electric current

A fuel system component located at the lowest point that traps water and sediment via a settling bowl before fuel reaches the carburetor.

• Installed at the system's lowest point
• Equipped with a clear bowl and drain for inspection
• Common on reciprocating engine fuel systems

Memory trick: Gascolator = gravity's collector, catching junk before the carb.

Nitrogen gas charge on one side of an accumulator piston/diaphragm that preloads stored hydraulic fluid for instant release.

• Precharge is typically about 1/3 of system operating pressure
• Dampens pressure surges and stores emergency power
• Piston, diaphragm, or bladder type accumulators

Memory trick: Nitrogen is the spring that pushes fluid out fast.

Regulation specifying when an ELT battery must be replaced or recharged based on usage time or expiration of useful life.

• Replace after 1 cumulative hour of use
• Or 50% of battery useful life expired, whichever first
• New expiration date must be marked on battery and recorded in maintenance records

Memory trick: '1 hour or half-life' — whichever hits first wins

A turn coordinator uses a gyro canted about 30° to sense both roll and yaw rate, giving earlier turn indication, while a turn-and-slip indicator's gyro spin axis is horizontal and senses only yaw rate.

• Turn coordinator gimbal canted ~30° from horizontal
• Senses roll rate plus yaw rate, shown as a miniature airplane symbol
• Turn-and-slip indicator uses a needle and senses only yaw rate about vertical axis

Memory trick: Tilt the gyro 30° to catch the roll before the turn.

A fuse is a one-time overcurrent device that melts to open a circuit, offering fast and precise protection, while a circuit breaker is a resettable mechanical device.

• Fuse melts and must be replaced after opening
• Fuses respond quickly since no mechanical linkage is involved
• Circuit breakers are resettable but slightly slower due to mechanical action

Memory trick: Fuse = one-shot flame, Breaker = reset button

The room-temperature strengthening of a solution heat-treated aluminum alloy as fine precipitates form within the grain structure over time.

• Occurs after solution heat treatment and quenching
• 2024 aluminum reaches full T3/T4 strength within about 4 days at room temperature
• Artificial aging uses elevated oven temperatures to accelerate the process (e.g., T6 temper)

Memory trick: Natural aging is the metal quietly getting stronger with age, like fine wine

2017-T4 and 2024-T4 aluminum rivets are solution heat treated, quenched, and stored refrigerated to keep them soft and workable until installation, since they naturally age harden at room temperature.

• Stored below freezing to slow natural aging
• 2017-T4 usable roughly 1 hour at room temperature
• 2024-T4 usable only about 10-20 minutes
• Must be re-refrigerated or re-heat-treated if the time limit is exceeded

Memory trick: Icebox rivets are like ice cream — melt (warm up) too long and they harden and spoil the job.

The center-to-center distance between rivets in the same row, generally specified as 6 to 8 times the rivet diameter for standard sheet metal repairs.

• Minimum pitch: approximately 6D to avoid sheet weakening.
• Typical maximum pitch: approximately 8D to maintain load transfer.
• Pitch works alongside edge distance and row spacing in repair layout.

Memory trick: '6 to 8 times D' — six to eight rivet diameters apart, like fence posts spaced evenly

The structural pin/journal that attaches the main landing gear strut to the aircraft structure, allowing rotation during retraction and extension.

• Carries heavy structural and landing loads
• Allows gear to rotate/pivot during retraction
• Closely inspected for cracks, wear, and corrosion

Memory trick: 'Trunnion turns the whole gear like a hinge'

The bucked (driven) head of a solid rivet should measure approximately 1.5 times the shank diameter, with a height of about 0.5 times the shank diameter.

• Driven head diameter ≈ 1.5D
• Driven head height ≈ 0.5D
• Undersized heads indicate weak, understrength rivets
• Oversized/cracked heads indicate overdriving

Memory trick: 1.5 times wide, half as tall — the golden rivet head rule.

A progressive fracture caused by repeated cyclic loading, identifiable by smooth concentric 'beach marks' radiating from an origin, ending in a rough final fracture zone.

• Begins at a stress concentration point (stress riser)
• Beach marks show progressive crack growth over cycles
• Final rupture area is rough/granular from sudden overload
• Common cause of in-service structural failures

Memory trick: Beach marks = waves on a beach, showing repeated cycles.

A protective relay that disconnects a DC generator from the bus when generator voltage drops below bus/battery voltage, preventing battery discharge back through the generator.

• Also called a cutout relay
• Senses reverse current flow direction
• Automatically opens generator-to-bus connection on generator failure

Memory trick: Reverse relay = the bouncer that kicks the dead generator out before it drains the battery.

A mechanical system using a float on the fuel surface connected via linkage or arm to a cockpit gauge to indicate fuel level.

• Simple, no electrical power needed for basic types
• Affected by aircraft attitude and fuel sloshing
• Less accurate than capacitance systems

Memory trick: Float = 'bobs with the wobbles' — inaccurate in turns

A system on some transport aircraft that allows rapid dumping of fuel overboard in flight to reduce aircraft weight to at or below maximum landing weight for an emergency return landing.

• Required on aircraft where max takeoff weight substantially exceeds max landing weight
• Fuel is dumped through wingtip or trailing edge nozzles
• System typically retains a minimum reserve fuel quantity even after full jettison

Memory trick: Jettison sheds fuel weight fast for a safe heavy landing.

The maximum distance allowed between clamps supporting an aircraft wire bundle to prevent sag, chafing, and vibration fatigue.

• General maximum spacing: 24 inches
• Closer spacing may be required near moving parts or high-vibration areas
• Improper spacing can cause chafing and eventual electrical shorts

Memory trick: 24 inches — two feet apart keeps wires from sagging like a hammock.

A repair technique where damaged or crushed honeycomb core is filled with a structural potting compound to restore support before bonding a skin patch.

• Crushed core loses its load-bearing capability
• Potting compound restores a solid, supportive base
• Common in sandwich panel repairs on flight control surfaces and fairings

Memory trick: 'Pot the Crush Before You Patch' — support first, cover second.

A riveted joint in which one piece of sheet metal overlaps another, with fasteners installed through the overlapping area.

• Common in doubler and patch repairs
• Simpler to fabricate than a butt joint with splice plate
• Creates a step in the skin surface, unlike a flush butt joint repair

Memory trick: Lap joint = one sheet 'laps over' the other like a lap blanket

Different hydraulic fluid types require specific seal elastomers to prevent chemical degradation.

• MIL-H-5606 (red, petroleum-based) uses neoprene/nitrile seals
• Skydrol/phosphate ester (purple) uses Butyl or EPR seals
• Never mix fluid types or seal materials

Memory trick: Purple Skydrol pairs with EPR, Red mineral oil pairs with neoprene.

A device that transfers hydraulic power from one system to another via a motor-pump combination, without mixing the fluids of the two systems.

• Motor side driven by System A fluid
• Pump side pressurizes System B fluid
• Provides redundancy if one system's pump fails

Memory trick: PTU is a matchmaker pump — energy crosses, fluid never mixes.

The process of adding weight forward of a control surface's hinge line to shift its center of gravity and prevent aerodynamic flutter.

• Moment = Weight x Arm distance from hinge line
• Weight = Moment ÷ Arm distance
• Improper balance can lead to dangerous flutter conditions

Memory trick: 'Moment over arm gives you the weight to disarm flutter.'

A one-way valve that allows free flow in one direction and completely stops flow in the reverse direction.

• No bypass or metering path in reverse direction
• Commonly a spring-loaded ball or poppet design
• Different from orifice check valve, which allows restricted reverse flow

Memory trick: Simple check valve = one-way street with a locked gate behind you

An electrically driven pump in the fuel tank that supplies fuel under positive pressure to the engine-driven pump inlet, preventing vapor lock.

• Prevents vapor lock at altitude/heat
• Used for engine starting and backup
• Independent of engine-driven pump

Memory trick: Boost pump BOOSTS pressure before the engine pump

A heavy longitudinal structural member running the length of a semi-monocoque fuselage, attached to bulkheads, that resists bending loads.

• Larger cross-section than stringers
• Spans between bulkheads
• Works with skin and frames to carry bending loads

Memory trick: Longeron = LONG and strong, the backbone beam.

An NDT method for ferromagnetic materials that magnetizes the part and applies iron particles to reveal surface and near-surface cracks via magnetic flux leakage.

• Only works on ferromagnetic materials like steel
• Cracks perpendicular to the magnetic field are most visible
• Part must be demagnetized after inspection to prevent residual magnetism issues

Memory trick: Magnets only love iron, and cracks leak the field like a broken dam