FAA Aviation Mechanic Airframe (AMA) flashcards

A pressure-sensing mechanism using a curved, flattened, sealed tube that straightens proportionally to internal pressure, driving a pointer through a gear sector and pinion linkage.

• Common in hydraulic, oil, and pneumatic pressure gauges
• Tube straightens as pressure increases
• Motion transmitted via linkage/gear sector to pointer

Memory trick: Bourdon tube bends back to tell you the pressure trend

TAS is CAS corrected for nonstandard density altitude; as altitude increases, air density decreases, so TAS exceeds CAS by roughly 2% per 1,000 feet.

• TAS > CAS at altitude due to lower air density
• Rule of thumb: add ~2% of CAS per 1,000 ft altitude
• Exact values require a flight computer or airspeed correction chart

Memory trick: Thinner air, faster TAS — climb and the gap grows.

Corrosion that occurs when moisture and debris are trapped in a tight crevice, such as a lap joint or under a fitting, forming a localized corrosive cell that can bulge the surrounding structure.

• Occurs in faying surfaces, seams, and under fasteners
• Caused by trapped moisture and contaminants
• Corrosion products expand and can bulge or pillow the skin
• Prevented by proper sealing and drainage

Memory trick: Poultice = like a wet bandage trapped against skin, festering underneath

A nondestructive inspection method using induced electrical currents to detect surface and near-surface flaws in conductive materials, often without removing paint.

• Works only on electrically conductive materials
• Can detect cracks around fastener holes without disassembly
• Sensitive to material conductivity changes, thickness, and flaws

Memory trick: 'Eddy Currents Swirl Through Paint' — no strip needed for surface cracks.

A vent line or valve that allows outside air to enter or leave a fuel tank so internal pressure stays close to ambient pressure.

• Prevents tank collapse from vacuum as fuel is used
• Prevents overpressure as altitude decreases
• Often includes a check valve and vent line routed outboard

Memory trick: Vent lets the tank breathe with the sky.

Examination of landing gear wheel bearings for damage such as spalling, pitting, corrosion, or overheating discoloration during scheduled inspections.

• Bearings must be cleaned and repacked with approved grease
• Spalling/pitting requires rejection
• Bluish discoloration may indicate overheating damage
• Bearings are matched sets and not interchanged with new rollers

Memory trick: Pits and spalls mean the bearing falls (out of service).

Lead wire connecting a thermocouple probe to its indicator must be made of the same dissimilar metal alloys as the thermocouple itself to avoid introducing false junctions that alter the generated voltage.

• Thermocouples generate voltage from junction of two dissimilar metals
• Common EGT thermocouple types: chromel-alumel or iron-constantan
• Mismatched lead wire alloys create parasitic junction voltages
• No external power source is needed; thermocouples are self-generating

Memory trick: Match the metals like matching puzzle pieces — mismatched alloys create a false extra junction that lies to the gauge.

A spring-loaded valve that opens to admit outside air into the cabin when outside pressure exceeds cabin pressure, preventing structural damage from inward pressure loads.

• Opens during rapid descent scenarios
• Prevents fuselage crush from negative differential
• Works opposite to positive pressure relief valve

Memory trick: Negative valve = guards against the cabin getting 'sucked in'

A calibrated stick inserted through a tank sump opening that uses a magnetic float to physically indicate fuel quantity, serving as a manual backup to electronic fuel gauges.

• Inserted through a calibrated tank access point
• Magnet engages internal float at fuel surface
• Provides manual cross-check for capacitance systems

Memory trick: 'Drip stick dips down to find where the fuel sits.'

A pressure-limiting valve set to open at a pressure slightly above normal system operating pressure, protecting components from damage due to overpressure.

• Opens at a preset maximum pressure
• Routes excess fluid back to reservoir
• Distinct from thermal relief valves, which protect isolated segments

Memory trick: Relief valve = the 'pressure cop' that stops things from blowing up.

A small relief valve installed to protect a length of tubing that can be isolated by shutoff valves on both ends, relieving pressure caused by fluid thermal expansion.

• Protects trapped, isolated fluid segments
• Opens at a lower pressure than the main system relief valve
• Common near landing gear and other valve-isolated sections

Memory trick: Thermal relief = the 'pressure release valve on a soda bottle left in the sun.'

The difference between the pressure inside a pressurized cabin and the ambient pressure outside the aircraft at altitude; it is a critical structural design limit.

• Differential = cabin pressure − outside ambient pressure
• Exceeding max differential can cause structural damage
• Typical transport aircraft max differential is around 8–9 psi

Memory trick: Differential is what's left after subtracting outside from inside.

A windshield anti-ice/anti-fog system using embedded conductive heating film with a temperature sensor and controller to regulate power and prevent overheating.

• Conductive film embedded in laminated windshield
• Controller regulates power based on windshield temperature
• Prevents overheating, cracking, or delamination

Memory trick: Controller = the windshield's thermostat, not its ice-spotter

A hinged linkage connecting the upper strut cylinder to the lower piston, transmitting torque to prevent piston rotation while allowing strut compression/extension.

• Prevents wheel/piston from rotating within the cylinder
• Allows telescoping motion of the shock strut
• Also used to actuate shimmy dampers or steering feedback in some designs

Memory trick: Torque link scissors keep the strut from spinning like a loose bolt

A hydraulic system in which fluid flows continuously from the pump through all selector valves (in series) and back to the reservoir until a valve is actuated to direct flow to a subsystem.

• Selector valves are wired in series
• Pump delivers constant flow, not constant pressure
• Common on older and lighter aircraft with fixed-displacement pumps

Memory trick: Open-center: 'Open road' — fluid keeps cruising until a valve redirects it.

A hydraulic power control unit in which actuator piston movement is mechanically fed back to reposition the metering valve toward neutral, stopping motion at the commanded position.

• Provides proportional, precise control surface positioning
• Metering valve returns to neutral as actuator reaches commanded position
• Common in transport aircraft primary flight control systems

Memory trick: Follow-up servo 'checks its work' by feeding position back to the valve.

A light fixture aimed at the wing leading edge to allow the flight crew to visually check for ice buildup during night operations.

• Provides illumination only, no heating
• Used on aircraft lacking automatic ice detectors
• Mounted on fuselage or wing to shine on leading edge

Memory trick: 'Ice light just lets the pilot LOOK, not COOK.'

Cracking caused by the combined action of sustained tensile stress and a corrosive environment on a susceptible metal, propagating perpendicular to the applied stress.

• Requires sustained (static) tensile stress, not cyclic loading
• Common in high-strength steel and aluminum alloys under residual or applied stress
• Cracks propagate transgranularly or intergranularly, often with little visible deformation

Memory trick: 'Stress + corrosion = a silent crack sneaking through.'

A pneumatically or electrically controlled valve that regulates the rate of air leaving a pressurized cabin to maintain a scheduled cabin altitude.

• Positioned by the cabin pressure controller
• Modulates continuously during flight
• Works with a separate safety relief valve for overpressure protection

Memory trick: Outflow valve is the cabin's exhaust throttle.

A structural landing gear member oriented fore-and-aft that absorbs taxi, takeoff, and landing drag loads and transfers them into the airframe.

• Resists fore-and-aft loads
• Works with side brace (lateral loads) and trunnion (pivot)
• Often incorporates a downlock mechanism
• Failure can allow gear to collapse rearward or forward

Memory trick: Drag brace drags the fore-aft load away.

A form of wear corrosion caused by small-amplitude repetitive motion between two tightly fitted surfaces, producing fine oxide debris and surface damage.

• Occurs at hinge points, bolted joints, bearing fits
• Produces reddish-brown powder on aluminum, black on steel
• Can lead to fatigue crack initiation if undetected

Memory trick: Fretting = friction + vibration = fine dust

The vertical sheet metal member connecting the upper and lower spar caps in a box beam spar, primarily designed to carry shear loads while the caps carry bending loads.

• Spar caps carry tension/compression bending loads.
• Web carries shear loads, similar to an I-beam web.
• Webs are often reinforced with vertical stiffeners to prevent buckling.

Memory trick: Caps = Compression/tension, Web = shear — 'Caps Bend, Web Shears'

A device that steps down AC voltage using a transformer and converts it to DC using rectifier diodes, commonly used in AC-primary electrical systems to supply DC buses and charge the battery.

• Combines a step-down transformer with a rectifier
• Converts 115V AC to 28V DC typically
• Used on aircraft where AC generators are the primary power source

Memory trick: TRU = 'Turn to DC, Reduce voltage, Use it' — transform then rectify.

A hydrometer measurement of electrolyte density used to determine the state of charge of a lead-acid battery.

• Fully charged: approx. 1.275–1.300
• Discharged: drops toward 1.150–1.200
• Readings must be corrected for electrolyte temperature

Memory trick: Heavy acid = healthy battery; watery acid = weak battery.

A wiring installation practice of physically separating wire bundles for redundant systems so that a single localized fault cannot disable both systems.

• Protects against single-point failures like chafing, fire, or mechanical damage
• Applies to critical/redundant flight control and electrical systems
• Often required by design standards for essential and backup circuits

Memory trick: Never put both parachutes in the same bag — separate redundant bundles.

When using an extension on a torque wrench, the wrench setting must be adjusted using TW = TA x [L / (L+A)] to compensate for the increased effective lever arm, ensuring the correct final torque is applied to the fastener.

• L = wrench handle length, A = extension length
• TA = desired actual torque at the fastener
• Wrench reading (TW) is set lower than TA when using an extension

Memory trick: Longer arm, lighter reading — extension multiplies force, so dial down the setting

A brake assembly using several alternating rotating and stationary discs compressed by hydraulic pistons to create braking friction, common on transport aircraft.

• Rotating discs are splined to the wheel
• Stationary discs are keyed to the torque tube
• Provides greater surface area and heat capacity
• Used on most large jet transport main gear

Memory trick: Many discs, many hands squeezing together = multiple-disc brake.

Self-locking nuts use either a fiber insert or an all-metal locking feature to resist loosening from vibration; the type selected depends on the operating temperature of the installation location.

• Fiber-insert (nylon) locknuts limited to about 250°F
• All-metal locknuts suitable for higher temperature areas like engine/exhaust zones
• Both resist nut rotation from vibration but by different mechanisms
• Not used where the nut is expected to be removed and reinstalled excessively without inspection

Memory trick: Fiber melts near fire — use all-metal near heat.

A switch mounted on the landing gear strut that senses strut compression to signal whether the aircraft is on the ground or in the air, used for gear/spoiler interlock logic.

• Senses strut compression from aircraft weight
• Prevents gear retraction while on ground
• Enables systems like spoilers/reversers only when confirmed on ground

Memory trick: Squat down = strut compresses = switch says 'we're on the ground'

A device, typically using diodes, that converts alternating current (AC) into direct current (DC) in an aircraft alternator system.

• Uses diodes that allow current flow in only one direction
• Found in brushless AC alternator systems
• Different from an inverter, which converts DC to AC

Memory trick: Rectifier = one-way valve for electrons

In a wye (Y) connected three-phase AC system, line voltage equals phase voltage times the square root of 3 (approximately 1.732).

• Line voltage = Phase voltage × 1.732
• Y connection provides both line and phase voltage access via neutral
• Common in aircraft brushless AC alternators

Memory trick: Y-connection: multiply phase voltage by 1.732 to get the line voltage.

A system using electrical heating elements on propeller blades, cycled by a timer to shed ice in sections while limiting electrical power demand.

• Heating elements bonded to blade leading edges
• Timer cycles power to limit electrical load
• Centrifugal force helps throw off loosened ice

Memory trick: Cycle to save power, spin to shed the ice

A component installed in the fuel system that removes water and solid contaminants from fuel before it reaches the engine.

• Has a drainable sump for removing collected water
• Prevents ice formation and pump/injector damage
• Should be drained regularly per maintenance schedule

Memory trick: Filter/separator is the fuel system's water trap.

The proper order of switch actuation and mechanical events during gear retraction, verified during a functional/rigging check: weight off wheels, downlock release, gear retraction, and uplock engagement.

• Squat switch must sense weight-off-wheels before retraction
• Downlocks must release before gear can move
• Gear retracts into wheel well after downlock release
• Uplocks secure gear up and extinguish position light

Memory trick: Weight off, lock off, gear goes, lock on.

The altimeter setting window; setting it to 29.92 in Hg standard pressure causes the altimeter to indicate pressure altitude, used above 18,000 ft MSL.

• 29.92 in Hg is standard sea-level pressure
• Used above 18,000 ft MSL for common altitude reference
• Local altimeter setting is used below 18,000 ft MSL

Memory trick: 29.92 = the standard 'reset button' above 18,000 feet

A pressure control valve used with fixed-displacement pumps that diverts pump output to the reservoir at low resistance once system pressure reaches the cutout setting.

• Used with constant-delivery pumps
• Cutout: diverts flow to reservoir at set high pressure
• Cut-in: restores normal delivery at a lower set pressure

Memory trick: Unloading valve = pump treadmill, spins free once it's 'full.'

An engine-driven hydraulic pump that automatically varies piston stroke to match system demand while maintaining constant pressure.

• Self-regulates output without external relief valve
• Contrasts with fixed displacement pumps needing a separate pressure regulator
• Common on large transport aircraft hydraulic systems

Memory trick: Variable pump breathes in and out with demand.

14 CFR 91.417 specifies retention periods for aircraft maintenance records, distinguishing between routine maintenance/AD compliance records and permanent records like total airframe time.

• AD compliance/routine maintenance records: 1 year or until superseded/repeated
• Total time in service, major repairs/alterations, life-limited parts status: retained for life of the airframe
• Records must be transferred with the aircraft upon sale

Memory trick: 'One year, unless it's forever' — routine vs permanent records

An NDT method that passes penetrating radiation through a part to produce an image revealing internal flaws, voids, or corrosion without disassembly.

• Uses X-ray or gamma radiation and film or digital detector
• Effective for internal defects in honeycomb, bonded, and thick structures
• Requires strict radiation safety controls and trained/certified personnel

Memory trick: 'X-ray sees through the skin like looking through a wall.'

Process of adjusting flight control cable tension to manufacturer specifications using a tensiometer, accounting for ambient temperature.

• Tensiometer measures cable tension in pounds
• Rigging charts list correct tension per temperature
• Improper tension causes control stiffness or slack

Memory trick: Hot day, loose cable — temperature sets the tension target

Localized corrosion that forms small cavities or pits on a metal surface due to a breakdown of the protective oxide layer, often leaving powdery deposits.

• Appears as isolated small holes/cavities
• Common starting point for stress corrosion cracking
• Caused by moisture, salt, or chemical exposure
• Detected visually or with a fine probe/depth gauge

Memory trick: Pitting = pockmarks, like tiny craters on the moon.

A bulging pattern in the outer skin of a honeycomb sandwich panel caused by trapped moisture expanding within the core cells.

• Visible as a 'pillowing' or quilted pattern matching the cell pattern
• Detected/confirmed with a coin tap test or moisture meter
• Can lead to core degradation, disbonding, and freeze-thaw damage

Memory trick: 'Pillowing = the core is soaked and puffing up like a pillow.'

A hydraulic reservoir supplied with bleed air or system pressure to maintain positive pressure at the pump inlet.

• Prevents pump cavitation at altitude
• Uses bleed air or system pressure
• Common on transport category aircraft

Memory trick: Push fluid to the pump so it never runs dry — pressurize!

A timed valve in a pneumatic deicing system that directs pressurized air sequentially to different sections of rubber boots to inflate and deflate them, breaking off ice.

• Powered typically by an engine-driven vacuum/pressure pump
• Boots inflate in a specific sequence to avoid ice bridging
• Deflated by vacuum between cycles for aerodynamic smoothness

Memory trick: Distributor valve is the boot system's traffic cop.

A magnetic compass error occurring on east/west headings in which acceleration causes an apparent turn toward north and deceleration causes an apparent turn toward south, due to compass card pendulosity and magnetic dip.

• ANDS = Accelerate North, Decelerate South
• Error is most pronounced on east/west headings
• No error occurs on north/south headings during acceleration
• Caused by pendulous mounting of the compass card combined with vertical dip component

Memory trick: ANDS: Accelerate North, Decelerate South — remember it like a compass speeding north when you step on the gas.

A timer-driven valve in a pneumatic deicing system that sequences bleed air pressure and vacuum to inflatable boot tube sections to shed ice.

• Creates the alternating inflate/deflate cycle
• Works with an ejector for vacuum during deflation
• Powered by engine bleed air pressure for inflation

Memory trick: Distributor 'deals the cards' of air to each boot section in order

A system that sprays isopropyl alcohol-based fluid onto the windshield to prevent ice and frost formation by lowering the freezing point of surface moisture.

• Uses alcohol-based fluid, often isopropyl alcohol
• Fluid is pumped from a reservoir to spray bars at the windshield base
• Alternative to electric or bleed-air heated windshields

Memory trick: Alcohol lowers the freeze point, like antifreeze on glass.

A manufacturer-published document providing approved data on allowable damage limits, repair procedures, and materials for aircraft structure.

• Provides blend-out and allowable damage limits
• Used to determine if damage is repairable or requires replacement
• Considered approved data for repairs when followed exactly
• Specific to aircraft make/model

Memory trick: SRM = 'Skin Repair Menu' — the recipe book for fixing dents

A fuselage structure built from welded steel tubing arranged in triangular (truss) patterns that carries all structural loads, with the covering providing shape only.

• Triangular tubing arrangement resists loads efficiently
• Common on early and light fabric-covered aircraft
• Covering (fabric/sheet) is non-structural
• Also called a Pratt or Warren truss configuration

Memory trick: Triangles in tubing = truss taking the tension.

A hydraulic valve that reduces main system pressure to a lower, regulated value for a subsystem such as wheel brakes.

• Protects lower-pressure-rated components
• Different function from priority valve (flow priority)
• Maintains constant reduced outlet pressure despite main system fluctuations

Memory trick: Reducer valve = a pressure 'step-down transformer' for brakes.

A lightweight sandwich panel core material made of aramid fiber paper dipped in phenolic resin, valued for corrosion resistance, moisture resistance, and good strength-to-weight ratio compared to aluminum honeycomb.

• Does not corrode like aluminum honeycomb when exposed to moisture.
• Lighter than aluminum honeycomb of similar strength.
• Common in aircraft interior panels, fairings, and control surfaces.

Memory trick: Nomex = 'No More' corrosion in moist conditions

A circuit breaker designed to open an overloaded circuit automatically regardless of the position of the operating control.

• Cannot be held closed by the switch during an overload
• Protects wiring from overheating even if crew tries to override it
• Required by 14 CFR for most aircraft circuit protection devices

Memory trick: 'Trip-Free' Frees the circuit even if you fight it

Standardized colored arcs and lines on an airspeed indicator denote specific operating speed ranges and limits for safe aircraft operation.

• White arc = flap operating range (Vso to Vfe)
• Green arc = normal operating range (Vs1 to Vno)
• Yellow arc = caution range; red line = Vne (never exceed)

Memory trick: White for wings with flaps down.

An aircraft tire that seals air directly against the wheel rim without using an inner tube.

• Bead seats against rim to form airtight seal
• Lighter and runs cooler than tube-type tires
• Damaged bead or rim can cause leaks

Memory trick: Tubeless = trust the bead, not a tube

A backup valve that opens to admit ram air into the cabin for ventilation when the normal pressurization system fails, interlocked to open only at low differential pressure and airspeed.

• Provides emergency ventilation, not full pressurization
• Interlocked with pressure differential and airspeed sensors
• Typically used at lower altitudes where cabin/ambient pressure difference is small

Memory trick: Ram air only opens when it's safe—low pressure, low speed.

Accumulators are typically precharged with nitrogen to about one-third of the hydraulic system's rated operating pressure.

• Precharge ≈ system pressure ÷ 3
• Too low precharge causes piston to bottom out
• Too high precharge reduces fluid storage capacity

Memory trick: Divide by three to find the nitrogen key.

Aircraft hydraulic fluids are dyed distinct colors to help identify fluid type and prevent accidental mixing of incompatible fluids.

• MIL-PRF-5606 mineral-base fluid is red
• Phosphate ester fire-resistant fluid (e.g., Skydrol) is purple
• Never mix fluid types—incompatible seals and chemistry

Memory trick: Purple = phosphate; Red = regular (mineral) fluid

A magnetic heading sensor, usually mounted in a wingtip or tail away from magnetic interference, that electrically transmits heading information to remote cockpit indicators via a synchro system.

• Mounted away from magnetic interference sources
• Sends signal through a synchro/autosyn transmission system
• Feeds remote indicators such as RMI, HSI, and autopilot heading systems

Memory trick: Flux valve is the wingtip 'compass spy' radioing heading data to the cockpit

A perforated tube running inside a wing leading edge that distributes hot engine bleed air along its length to prevent ice formation.

• Uses engine bleed air, not electric heat
• Perforations spray hot air against the inner leading edge skin
• Common on transport category turbine aircraft

Memory trick: Piccolo tube plays a tune of hot air along the wing.

A system that automatically modulates brake pressure to individual wheels to prevent skidding during heavy braking.

• Uses wheel-speed transducers to detect impending skid
• Releases brake pressure momentarily to restore rolling traction
• Improves stopping distance especially on wet/icy runways

Memory trick: Anti-skid pumps the brakes for you, like ABS in a car