FAA Aviation Mechanic Airframe (AMA) flashcards

A switch with a single common terminal that can be connected to one of two other terminals, used to select between two circuit paths.

• Pole = number of common terminals
• Throw = number of positions/contacts per pole
• SPDT allows selecting between two circuits from one switch

Memory trick: Pole = paths in, Throw = paths out.

A spring-loaded check-valve fitting used to service pneumatic bottles or accumulators with gas from a ground cart, automatically sealing when the servicing hose is disconnected.

• Contains an internal check valve for automatic sealing
• Commonly used for nitrogen or air servicing of accumulators/bottles
• Prevents pressure loss without needing a manual shutoff valve

Memory trick: Charging valve: like a bike tire valve that seals itself after pumping

A nondestructive inspection method using high-frequency sound waves to detect internal flaws, thickness variations, and delaminations in materials.

• Detects subsurface defects in thick materials
• Uses transducer and reflected sound wave analysis
• Works on metals and composites

Memory trick: Ultrasonic = 'echo location' finding hidden cracks deep inside

A letter-number code following the alloy number that describes the heat treatment and/or mechanical working applied to aluminum sheet.

• O = annealed (softest)
• T3 = solution heat treated + cold worked
• T4 = solution heat treated + naturally aged
• T6 = solution heat treated + artificially aged

Memory trick: 'T3, Three steps: Treat, then Twist (cold work).'

A hydraulic valve/cylinder that reduces high system pressure to a lower regulated pressure for brake application while increasing fluid volume delivered to the brake.

• Protects brakes from full system pressure
• Increases volume while reducing pressure (piston area ratio)
• Common on aircraft with high-pressure hydraulic systems and lower-rated brakes

Memory trick: 'Deboost = de-boosting the pressure down to brake-safe levels'

A special inspection performed after a lightning strike to locate localized burn damage, pitting, or delamination at entry and exit points.

• Damage is often localized at strike attachment/exit points
• May require NDT (e.g., tap test) to find hidden delamination on composites
• Bonding and static wick continuity should also be checked

Memory trick: 'Lightning burns a hole, then hides damage below.'

A destructive condition where decreasing internal resistance causes charging current and temperature to increase uncontrollably, potentially destroying the battery.

• Signs: excessive heat, case swelling/warping, strong odor, high charge current
• Caused by internal short or voltage regulator malfunction
• Requires immediate removal of battery from charging circuit

Memory trick: Runaway battery runs hot and never stops until you pull the plug

A visual indication of dark staining around a rivet caused by relative movement (fretting) between the rivet and surrounding skin, signaling a fatigued or loose joint.

• Caused by fretting motion producing aluminum oxide dust
• Common on riveted lap joints under cyclic loading
• Warrants further inspection (NDT) or rivet replacement

Memory trick: 'Smoking rivet' = the joint is literally crying out that it's loose

A valve that ensures one hydraulic actuator completes its motion before pressure is allowed to another actuator, enforcing a required order of operations such as gear doors opening before gear retraction.

• Common in landing gear door/gear circuits
• Opens only after upstream pressure reaches a set value, indicating prior actuator has completed its stroke
• Prevents mechanical interference between components

Memory trick: Sequence valve = 'traffic light' making doors go green before gear moves.

A fine wire mesh screen installed in a fuel tank vent line that quenches heat and prevents external flame from propagating into the tank.

• Located at or near the vent outlet
• Absorbs heat to quench flame front
• Prevents fuel tank explosion from external fire sources

Memory trick: The mesh is a fire net, catching flames before they reach the tank.

The regulatory checklist defining the minimum scope and detail of items that must be inspected during an annual or 100-hour inspection.

• Applies to both annual and 100-hour inspections
• Lists items such as fuselage, engine, landing gear, wings, control system
• Serves as the minimum baseline; manufacturer checklists may be more detailed

Memory trick: Appendix D = 'Detailed' inspection list

An advanced form of intergranular corrosion in extruded/rolled high-strength aluminum where surface layers lift and separate along elongated grain boundaries.

• Common in extrusions/forgings with elongated grain flow
• Layers lift like pages of a book
• Advanced form of intergranular corrosion

Memory trick: Exfoliation = EXtruded metal peels like a book's leaves.

A form of corrosion appearing as random, thread-like filaments beneath a paint or organic coating, caused by moisture entering through coating defects.

• Occurs under paint/coating films
• Thin, worm-like random trails
• Promoted by high humidity and coating breaks

Memory trick: Filiform = Filament worms crawling under paint.

A valve that reduces high storage bottle pressure to a lower, regulated working pressure for pneumatic system components.

• Common on emergency pneumatic gear extension systems
• Maintains constant output pressure as bottle pressure decays
• Similar function to a hydraulic pressure reducing valve but for compressed gas

Memory trick: Regulator = 'gas step-down transformer' for pneumatic pressure

An NDI method limited to ferromagnetic materials where the part is magnetized and fine iron particles are applied; particles cluster at cracks due to magnetic flux leakage, revealing the flaw.

• Works only on ferromagnetic metals (iron, steel, nickel, cobalt)
• Detects surface and near-surface discontinuities
• Part must be demagnetized after inspection
• Common for landing gear and engine steel components

Memory trick: Magnets stick to steel — MPI sticks to ferromagnetic flaws.

The output frequency of an AC generator is determined by the number of poles and rotational speed using f = (P × N)/120.

• P = number of poles, N = RPM
• Standard aircraft AC frequency is typically 400 Hz
• Higher pole count or higher RPM increases frequency

Memory trick: Poles times speed, divided by one-twenty, gives frequency plenty

A system that automatically schedules cabin altitude versus aircraft altitude and commands the outflow valve position to maintain that schedule.

• Follows a preset cabin altitude-vs-aircraft altitude schedule
• Signals outflow valve motor to adjust cabin pressure
• Separate from safety and negative pressure relief valves

Memory trick: The controller is the conductor, keeping the cabin's 'altitude orchestra' in schedule.

A fuel tank formed by sealing existing wing structure (ribs, spars, skin) rather than installing a separate tank, commonly called a 'wet wing.'

• Uses fuel-resistant sealant on structural joints
• Maximizes fuel volume with minimal added weight
• Common on transport-category wings

Memory trick: IRA-D: Integral, Rigid, Auxiliary(bladder), Drop

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

• Clear ringing sound = solid bond
• Dull/flat sound = delamination or void
• Common on composite skins, honeycomb panels, and bonded structures

Memory trick: Dull thud = 'dud' bond underneath

An electronic circuit protection device that detects the distinctive current signature of arcing faults and trips to prevent wiring-related fires, even when current levels are below a conventional breaker's trip threshold.

• Uses electronic waveform analysis to detect arcing
• Protects against intermittent/low-current arc faults from chafed wiring
• Increasingly required in modern transport-category aircraft wiring

Memory trick: AFCB = the breaker that listens for the crackle of an arc, not just the heat of overload.

An additive blended into turbine fuel that depresses the freezing point of entrained water to prevent ice formation in the fuel system.

• Common additive: Prist
• Prevents ice crystal blockage of filters/lines
• Has secondary mild anti-microbial effect

Memory trick: FSII keeps water from freezing solid in the fuel.

Per 14 CFR 43.16, operators must comply with mandatory replacement times, inspection intervals, and procedures set forth in the ALS of the FAA-approved maintenance manual; these are treated as airworthiness directives.

• Governed by 14 CFR 43.16
• Applies to all operators regardless of operating rule
• Can only be changed via an FAA-approved revision

Memory trick: ALS = Absolutely, Legally Set (no local edits)

An electromagnetic relay that uses a low-current control circuit to open or close the high-current path between the battery and the main electrical bus.

• Energized by the battery master switch
• Closes heavy contacts to connect battery to bus
• Protects cockpit switch from carrying high battery current

Memory trick: Small switch, big muscle — the solenoid does the heavy lifting.

A DC generator voltage regulator that varies field circuit resistance by mechanically compressing or releasing a stack of carbon discs in response to output voltage changes.

• Sensing coil pulls plunger against spring pressure as voltage rises
• Less compression = higher carbon pile resistance = less field current
• Provides continuous negative-feedback voltage control

Memory trick: Squeeze the carbon less, resistance grows, field current slows, voltage goes low.

A valve with a free-floating shuttle that automatically routes whichever of two pressure sources is higher to a common outlet, isolating the lower-pressure source.

• Used for emergency brake or gear systems with dual pressure sources
• Shuttle physically blocks the unpressurized/low-pressure port
• Requires no pilot selection—operates automatically

Memory trick: Shuttle 'runs' to the winning (higher) pressure side

The pressurization controller modulates the outflow valve to limit how fast cabin altitude changes, typically to about 500 fpm for passenger comfort.

• Rate = cabin altitude change ÷ time
• Typical maximum comfort rate is around 500 fpm
• Controlled by outflow valve modulation via the cabin pressure controller

Memory trick: Ears like it slow—500 fpm or less keeps passengers happy.

A specification stating the size, in microns, of the smallest particles a hydraulic filter element is designed to trap.

• 1 micron = 0.000039 inch
• Absolute rating = largest particle guaranteed to be stopped
• Finer ratings increase filtration but may increase pressure drop

Memory trick: Micron = the mesh size guarding against grit.

A form of corrosion that progresses along the grain boundaries of a metal, often caused by improper heat treatment, weakening the material without much visible surface change.

• Follows grain boundaries rather than the surface broadly
• Often caused by improper heat treatment of aluminum alloys
• Can progress into exfoliation corrosion if severe

Memory trick: 'Inter-granular travels between the grains, like a rat through walls.'

Wiring batteries in series adds voltage while capacity stays the same; wiring in parallel keeps voltage the same while capacity adds.

• Series: voltages add, capacity (Ah) unchanged
• Parallel: voltage unchanged, capacity (Ah) adds
• Same current flows through series-connected batteries

Memory trick: Series stacks Volts; Parallel pools Amps.

Dry nitrogen gas is used to charge aircraft pneumatic systems and accumulators because it is inert and moisture-free, minimizing corrosion, ice formation, and fire risk compared to shop compressed air.

• Nitrogen does not support combustion
• Moisture-free gas prevents internal corrosion and ice during rapid expansion
• Shop compressed air is not used because of moisture and contamination content

Memory trick: Nitrogen = the 'dry, calm gas' that won't rust pipes or feed a fire.

The difference between cut-out and cut-in pressures on a pressure switch controlling an electric auxiliary hydraulic pump, preventing rapid cycling.

• Differential = cut-out pressure minus cut-in pressure
• Example: 3,000 psi cut-out − 2,700 psi cut-in = 300 psi differential
• Prevents motor chatter/rapid cycling near a single pressure point

Memory trick: Differential = a buffer zone so the motor doesn't flicker on/off like a bad light switch

An NDI method using a visible or fluorescent dye penetrant to reveal surface-breaking cracks and defects in nonporous materials, including nonferrous metals.

• Works on any nonferrous or ferrous nonporous material
• Detects only surface-breaking defects
• Process: clean, apply penetrant, remove excess, apply developer, inspect
• Cannot detect subsurface flaws like ultrasonic or radiographic methods

Memory trick: Dye penetrant paints the crack for anyone to see.

Federal regulation specifying the minimum content required in maintenance record entries after work is performed.

• Must describe the work performed
• Must include date of completion
• Must include signature, certificate number, and type of certificate of approving person

Memory trick: 'DDSC' — Description, Date, Signature, Certificate

A required periodic functional and altitude reporting test of the ATC transponder system performed every 24 calendar months per 14 CFR 91.413.

• 24-calendar-month interval
• Required for operation in controlled airspace requiring transponder use
• Must be performed per 14 CFR Part 43 Appendix F test procedures

Memory trick: 'Transponder Talks every Two years' — 24 months.

A short wing rib extending from the front spar forward to the leading edge, used to maintain the airfoil contour ahead of the main structure.

• Located only forward of the front (leading edge) spar
• Does not extend to the trailing edge like a main rib
• Common on wings with a single main spar and separate leading edge structure

Memory trick: Nose rib guards just the nose of the wing

A pressurization safety system that activates a horn and light when cabin altitude reaches approximately 10,000 feet, alerting the crew to a possible pressurization failure.

• Activates near 10,000 ft cabin altitude
• Normal cruise cabin altitude is ~8,000 ft or less
• Alerts crew before oxygen becomes critical

Memory trick: 'Ten grand, sound the horn'

Environmental degradation of pneumatic deicer boot rubber caused by prolonged exposure to ozone and ultraviolet light, resulting in fine surface crazing.

• Distinct from mechanical flex-fatigue cracking
• Accelerated by outdoor storage and sun exposure
• Requires boot replacement if cracking is significant

Memory trick: Sun and smog age rubber like sunburned skin, cracking the surface.

A spring-loaded valve built into a hydraulic filter assembly that opens to allow unfiltered flow to continue if the filter element becomes excessively restricted, preventing system flow interruption.

• Opens at a set differential pressure across the filter
• Paired with a pop-out differential pressure indicator
• Protects system flow at the cost of temporarily bypassing filtration

Memory trick: Bypass valve = 'emergency detour' around a clogged filter to keep traffic moving.

Dry nitrogen is used to pressurize oleo pneumatic shock struts because it is inert, moisture-free, and non-combustible.

• Prevents internal corrosion from moisture
• Non-flammable, unlike oxygen
• Standard gas specified in maintenance manuals for strut servicing

Memory trick: 'Nitrogen keeps it dry and inert - no fire, no rust'

Fuel weight is found by multiplying the volume of fuel (gallons) by its density (lb/gal); Jet A is typically 6.7 lb/gal.

• Jet A standard density: 6.7 lb/gal
• Avgas standard density: 6 lb/gal
• Weight = volume × density

Memory trick: '6.7 for Jet, 6 for gas' — remember densities by fuel type

A weight-on-wheels switch mounted on the landing gear strut that signals whether the aircraft is on the ground or in flight.

• Activated by strut compression/extension
• Prevents inadvertent gear retraction on ground
• Also used for spoiler, pressurization, and warning system logic

Memory trick: Squat = 'squished' strut tells the plane it's on the ground

Small conductive rods mounted at trailing edges of wings and control surfaces to safely discharge static electricity buildup from the airframe.

• Provide a path for precipitation static to exit the airframe smoothly
• Missing wicks cause radio static and navigation interference
• Bonding straps and static wicks work together for electrical continuity

Memory trick: Static wicks are lightning rods that quietly bleed off the charge

The process of properly filling an air-oil (oleo pneumatic) shock strut with hydraulic fluid and nitrogen to the manufacturer's specified levels.

• Strut must be deflated and extended before adding fluid
• Fluid level checked per manufacturer chart at specific extension
• Nitrogen charge added last to correct pressure/extension

Memory trick: Deflate, fill, then inflate—like changing a bike tire tube

The allowable shear load a rivet can carry equals its allowable shear stress multiplied by its cross-sectional shear area (A = π/4 × d²).

• Shear area formula: A = (π/4)d²
• AD (2117-T4) rivet allowable shear stress ≈ 30,000 psi
• Compare calculated allowable load to actual applied load for adequacy

Memory trick: Shear load = Stress × Area — plug and check against the load.

A condition where insufficient fluid supply at the pump inlet causes vapor bubbles to form and collapse, producing noise, pressure fluctuations, and pump damage.

• Caused by low reservoir fluid, clogged inlet screen, or excessive fluid viscosity
• Produces distinctive whining/growling noise
• Leads to pitting/erosion of pump internal components over time

Memory trick: Cavitation = pump gasping for fluid, bubbles popping like tiny explosions inside

A one-way flapper valve located in internal wing tank baffles that allows fuel to flow toward the boost pump sump while limiting reverse surge.

• Keeps fuel pooled around the boost pump inlet
• Opens one direction, closes to prevent surge-away flow
• Reduces risk of pump cavitation during maneuvers

Memory trick: Flapper lets fuel in toward the pump but blocks it from running away.

A heavily reinforced wing rib located at points of concentrated loading, such as landing gear attach points or drag/anti-drag wire bracing, designed to resist compressive loads in addition to maintaining airfoil shape.

• Heavier construction than plain (main) ribs
• Located at concentrated load points (gear, bracing, fittings)
• Resists compressive loads from bracing wires
• Distinct from nose ribs, which only shape the leading edge

Memory trick: Compression rib = the wing's weightlifter, handling the heavy squeeze.

The property of hydraulic fluid whereby its volume changes negligibly under pressure, allowing near-instantaneous and precise transmission of force through a hydraulic system.

• Hydraulic fluid: essentially incompressible
• Air/nitrogen: compressible, elastic response
• Incompressibility enables precise primary flight control actuation

Memory trick: Liquid punches instantly; gas gives a springy shove.

A rating expressing how much current a battery can supply over time, calculated as capacity (Ah) divided by discharge current (A) equals hours of use.

• Ampere-hour = amps × hours battery can sustain
• Formula: time (hr) = capacity (Ah) / load current (A)
• Actual endurance is reduced by higher discharge rates and cold temperatures

Memory trick: Amp-hours divided by amps drawn tells you how long the juice will run

Aluminum alloy sheet with a thin coating of pure aluminum bonded to one or both surfaces for corrosion protection.

• Pure aluminum layer is anodic and sacrificially protects the alloy core
• Used extensively for aircraft skins (e.g., 2024, 7075 alloys)
• Cladding is soft and can be worn through by excessive polishing or sanding

Memory trick: Alclad = Aluminum's coat of armor

A transformer using a single tapped winding shared by both primary and secondary circuits, providing voltage step-up or step-down without electrical isolation, but lighter and more efficient than a two-winding transformer.

• Single winding with a tap, shared by primary and secondary
• No electrical isolation between input and output
• Lighter and more efficient than isolation transformers of same rating

Memory trick: Auto shares one coil — no wall between in and out.

A gear design where the wheel/axle is mounted on an arm trailing behind the strut pivot, which rotates upward as the strut compresses, improving shock absorption.

• Wheel mounted on a pivoting trailing arm
• Provides smoother, more absorbent touchdown
• Common on business jets and off-airport capable aircraft

Memory trick: 'Trailing link trails behind like a dog on a leash, softening the bump'

A solid aluminum rivet with a low dome-shaped head used for the majority of protruding-head sheet metal repairs.

• Replaced round-head (AN430) and brazier-head rivets in most applications
• Head shape is a low, flat dome
• Identified by shank diameter and length codes stamped after AN470

Memory trick: 'Universal' rivets Uniformly replace old round heads.

An FAA-approved inspection program under 14 CFR 91.409(d) that divides the total annual inspection workload into smaller segments performed at scheduled intervals, ensuring the entire aircraft is inspected within a set cycle.

• Must be approved by the FAA before use
• Allows continuous operation without a single large annual inspection downtime
• Total inspection of all items must be completed within the approved cycle, commonly 12 months

Memory trick: Progressive inspections nibble the annual bit by bit instead of one big bite

A hydraulic pump that delivers a constant volume of fluid per shaft revolution regardless of system pressure, requiring external pressure regulation.

• Constant output per revolution
• Requires unloading/relief valve for pressure control
• Simpler design than variable-displacement pumps

Memory trick: Fixed pump = fixed scoop size every spin, no matter the thirst.

A dichromate-based chemical conversion treatment specifically formulated to protect magnesium alloy surfaces from corrosion, distinct from aluminum treatments.

• Magnesium is highly anodic and corrodes more readily than aluminum
• Requires dedicated treatments (e.g., dichromate process) rather than aluminum's Alodine/anodizing
• Magnesium components are common in older aircraft wheels, gearboxes, and control surfaces

Memory trick: Magnesium needs its own dichromate 'medicine,' not aluminum's Alodine

A manufacturer's chart correlating ambient temperature to the correct extended length of an air/oil shock strut, used because gas volume varies with temperature.

• Gas volume expands/contracts with temperature changes
• Extension measured with aircraft on jacks or at rest
• Ensures correct strut charge regardless of ambient conditions
• Different from checking pressure gauge alone

Memory trick: Hot air stretches, cold air shrinks — chart tells the right length.

A system that sprays a chemical fluid onto the windshield exterior to cause rain to bead and be removed by airflow, improving visibility in heavy rain.

• Activated by a pilot push-button switch
• Dispenses a metered fluid charge per activation
• Reduces surface tension so rain beads and blows off

Memory trick: Repellent makes rain 'bead and flee' off the glass in the wind.

A rigging verification using a protractor or travel board to confirm control surface deflection matches manufacturer-specified limits in both directions.

• Performed after any rigging, repair, or cable replacement
• Deviation can reduce control authority or contribute to flutter
• Checked with a protractor, travel board, or rigging fixture per maintenance manual

Memory trick: 'Travel limits keep the surface from flapping into flutter.'

An ice detection sensor that vibrates a small probe at a known resonant frequency; ice accumulation adds mass that lowers the frequency, which the system interprets as ice buildup.

• Common on turbine and helicopter ice protection systems
• Frequency decrease is proportional to accumulated ice thickness
• Often self-deices periodically by internal heating to reset baseline

Memory trick: Ice adds weight, slowing the rod's vibrating hum.