FAA Aviation Mechanic Airframe (AMA) flashcards

A required inspection for aircraft used for hire or flight instruction, performed every 100 hours of flight time, with the same scope as an annual inspection.

• Required under 14 CFR 91.409 for aircraft used commercially or for instruction
• Scope matches annual inspection per 43.15
• Can be performed by any certificated A&P mechanic

Memory trick: 100-hour = Annual twin, but A&P can sign it

A pressure-storage device using a gas charge to maintain hydraulic pressure on the parking brakes after the pump is shut down, compensating for minor fluid leakage.

• Uses compressed gas (often nitrogen) against a piston or diaphragm
• Maintains brake pressure with pump off
• Common in parking brake circuits to hold brakes over time

Memory trick: 'Accumulator is the battery of hydraulic pressure, holding the brake charge'

A geometric discontinuity, such as a sharp corner, notch, or scratch, that concentrates stress locally far above the nominal stress level, making it a likely site for fatigue crack initiation.

• Sharp corners, notches, and scratches all act as stress risers.
• Fatigue cracks typically start at stress risers under cyclic loading.
• Rounding corners (adding a fillet radius) reduces stress concentration.

Memory trick: Sharp corner = a lightning rod for stress — cracks strike there first

A yellow-green corrosion-inhibiting primer applied to bare metal aircraft structure before painting, providing corrosion protection and a bonding surface for topcoats.

• Distinctive yellow-green color
• Chromate ions passivate the metal, inhibiting corrosion
• Must be applied over clean, properly prepared bare metal

Memory trick: 'Yellow-Green Means Corrosion is Seen (and stopped)' — zinc chromate protects bare metal.

A tire built with plies of cord fabric laid diagonally across the carcass at alternating angles between the beads, providing strength through crossed layers.

• Plies cross at alternating angles bead-to-bead
• Older/more common construction on many aircraft tires
• Contrasts with radial-ply which has straight plies plus belts

Memory trick: 'Bias crosses like an X, radial runs straight across'

The ratio of scarf (taper) length to laminate thickness used in composite repairs to gradually transfer load between original structure and repair plies; structural repairs commonly specify ratios such as 30:1 per the manufacturer's SRM.

• Scarf length = ratio × laminate thickness.
• Higher ratios provide a shallower taper and larger bonding area.
• Exact ratio (e.g., 20:1, 30:1, 50:1) is specified by the aircraft's structural repair manual.

Memory trick: Scarf length = Ratio × Thickness, like stretching dough thin and long

A non-electrical outside air temperature gauge that uses a bimetallic strip which bends with temperature change to move an indicator needle.

• No electrical power required
• Bimetallic strip made of two metals with different expansion rates
• Common on light aircraft for simple temperature indication

Memory trick: Bimetal bends like a bent thermometer needle

The distance the jaws of a brake must be set back from the mold line to form a bend, based on bend radius and material thickness.

• For 90° bend: SB = R + T
• K-factor = tan(bend angle/2)
• Used to locate bend tangent lines on flat pattern layout

Memory trick: Setback = Radius + Thickness, Same Back-up amount.

A composite ply stacking sequence (typically 0°, +45°, -45°, 90°) designed to give approximately equal strength and stiffness in all in-plane directions.

• Mimics isotropic behavior of metals
• Common in structural repair patches needing multidirectional strength
• Must follow approved repair data for ply count, order, and orientation

Memory trick: '0-45-Negative45-90, spread strength all around' — quasi-isotropic covers every angle.

A field test using a calibrated punch tester pressed against fabric covering to estimate its remaining tensile strength for airworthiness determination.

• Common tester: Maule fabric strength tester
• Compares result to minimum strength requirement (e.g., ASTM D3999)
• Deteriorated fabric strength below minimum requires recovering

Memory trick: 'Punch it to see if it will crunch' — testing fabric's remaining strength.

A solid-state device that converts DC to AC using transistor oscillator and transformer circuitry, with no moving parts, unlike a rotary inverter which uses a motor-generator set.

• No moving parts — reduced maintenance vs rotary inverter
• Used to supply AC power for instruments from DC battery bus
• Rotary inverters use a DC motor driving an AC generator

Memory trick: Static stands still — no spinning parts to wear out.

An electrical architecture separating essential and non-essential buses via an isolation relay; during reduced generating capacity, non-essential loads are shed to protect essential equipment.

• Essential bus powers flight-critical equipment
• Non-essential bus can be isolated during generator failure
• Load shedding may be automatic or manual to conserve battery/generator capacity

Memory trick: Split the buses, shed the extras, save the essentials.

An operational test verifying the pitot tube's electric heating element is functioning, confirmed by increased current draw and a warm tube when activated.

• Prevents pitot tube icing in flight
• Verified by ammeter/annunciator current increase
• Failure results in blocked pitot tube and unreliable airspeed indications

Memory trick: Warm tube + rising ammeter needle = heat is working

TAT is the temperature of air after it is brought to a near-complete stop at the probe, which is warmer than static air temperature (SAT) due to kinetic (ram) heating from air deceleration.

• TAT = SAT + ram temperature rise from air compression
• Ram rise increases with airspeed (more pronounced at high Mach)
• Used to correctly compute true airspeed and engine performance parameters

Memory trick: Stop the air, and its speed turns to heat — that's your ram rise.

A heat exchanger in the turbine engine fuel system that warms fuel using hot engine oil (or bleed air) to prevent ice crystal accumulation on fuel filters.

• Uses hot oil or bleed air as the heat source
• Prevents fuel filter icing at altitude
• Works alongside, not instead of, FSII additive

Memory trick: 'Heater Hugs the Filter to keep it warm.'

Distinct tread wear patterns that diagnose specific landing gear or inflation problems.

• Center wear = overinflation
• Shoulder/edge wear = underinflation
• Feathered rib edges = misalignment/scrubbing

Memory trick: Feathered edges feel the friction of a crooked wheel

A transverse (ring-shaped) structural member in a semi-monocoque fuselage that maintains the cross-sectional shape and distributes loads into the skin, but does not run the length of the fuselage.

• Runs perpendicular (transverse) to the fuselage's longitudinal axis.
• Maintains fuselage shape and distributes concentrated loads.
• Works with longerons and stringers, which run longitudinally.

Memory trick: Bulkhead = a barrel hoop holding the fuselage's round shape

A placard mounted near the magnetic compass showing the correction to apply for deviation errors at various headings, created by swinging the compass on a compass rose.

• Deviation is caused by aircraft's own electrical and magnetic equipment
• Compass swing is performed on a calibrated compass rose
• Card typically lists corrections every 30 degrees
• Should be re-swung after avionics installation or major electrical changes

Memory trick: Swing the compass like a pendulum on the rose to write the 'cheat sheet' card for the pilot.

Stringers are lightweight, numerous longitudinal skin stiffeners that prevent buckling and distribute loads, whereas longerons are the heavier, primary longitudinal load-carrying members in a semi-monocoque structure.

• Stringers are more numerous and lighter than longerons
• Stringers primarily stabilize skin against buckling
• Longerons are the main heavy longitudinal load path
• Both run the length of the fuselage between frames/bulkheads

Memory trick: Longerons are the 'long strong' bones; stringers are the many small strings holding skin taut.

An aural alert triggered by throttle (and/or flap) position when the landing gear is not down and locked at low power settings, warning of a possible gear-up landing.

• Activated by throttle lever position switch
• May also be tied to flap position
• Alerts pilot before landing with gear retracted
• Separate system from squat switch weight sensing

Memory trick: Throttle back, horn honks back if gear's not down.

A valve that allows full flow in one direction and restricted, metered flow through an orifice in the reverse direction.

• Used to control actuator speed (e.g., gear retraction)
• Differs from simple check valve which fully blocks reverse flow
• Common in landing gear and flap systems

Memory trick: One way is a highway, the other way is a tiny tunnel.

A valve that allows the pilot to select which fuel tank(s) supply the engine, typically with LEFT, RIGHT, BOTH, and OFF positions on light aircraft.

• BOTH is used for takeoff and landing to prevent unporting
• OFF is used for shutdown or maintenance
• Individual tank positions are used in cruise to balance fuel load

Memory trick: BOTH for takeoff and landing keeps you steady, no matter how you're banking or heading.

Small conductive devices mounted on trailing edges of control surfaces that provide a path for static electricity to discharge from the airframe into the atmosphere.

• Prevent P-static interference with radios and navigation
• Mounted at trailing edges where airflow separates
• Must maintain proper resistance value per maintenance manual specs

Memory trick: Wicks 'wick away' static like a candle wick draws wax

A design practice of powering gyroscopic flight instruments from two independent sources (vacuum and electrical) so that failure of one source does not eliminate all attitude/heading references.

• Typical setup: vacuum-driven attitude/heading indicators, electric turn coordinator
• Protects against single-point failure of vacuum pump or electrical system
• Important for maintaining instrument reference during IFR flight

Memory trick: Don't put all your gyros in one power basket.

A sensor mounted on each braked wheel that generates an electrical signal proportional to wheel rotational speed, used by the anti-skid control unit to detect impending skids.

• Located at each main gear wheel with anti-skid
• Sends speed signal to anti-skid control box
• Failure can cause loss of skid protection at that wheel

Memory trick: 'The wheel's own speedometer tattles to the anti-skid brain'

A hydraulic or mechanical device on the nose landing gear that dampens lateral oscillation (shimmy) during ground operations.

• Prevents rapid side-to-side wheel oscillation
• Can be piston-type (hydraulic) or vane-type
• Low fluid or worn seals cause shimmy to reappear

Memory trick: Shimmy damper stops the wobble like training wheels

A visual NDT method using a rigid or flexible optical device inserted through small access points to inspect internal structures without disassembly.

• Used for spars, fuel tanks, engine interiors
• Minimizes need for structural disassembly
• Can be rigid or flexible fiber-optic/video type

Memory trick: Borescope = 'periscope for the inside of the plane'

A fuselage design in which the outer skin carries all primary stress loads, with internal formers/bulkheads only used to maintain shape.

• Skin alone bears bending, torsion, and shear loads
• No stringers or longerons present
• Heavier skin required than semi-monocoque designs
• Rare in modern aircraft due to weight penalty

Memory trick: Mono = one shell doing all the work.

A stress that results when a structural member is twisted about its longitudinal axis, common in wing spars and shafts.

• Five basic stresses: tension, compression, shear, bending, torsion
• Torsion twists a member about its long axis
• Wing spars and drive shafts commonly experience torsion

Memory trick: 'Torsion Twists, like Twisting a wet towel.'

A mechanical lock that secures the landing gear in the fully extended (down) position, preventing collapse or inadvertent retraction.

• Must release before gear can retract
• Often spring-loaded or hydraulically actuated to release
• Failure to release prevents gear-up selection

Memory trick: 'Downlock locks it down until told to let go'

A complete inspection required every 12 calendar months for all Part 91 aircraft, performed only by an IA holder or an appropriately rated repair station.

• Required under 14 CFR 91.409(a)
• Due at the end of the 12th month after the last annual, not the exact date
• Must be signed off by an IA-certificated mechanic

Memory trick: 12 months for annual, 24 for altimeter, 100 hours for 100-hour

An NDT method using high-frequency sound waves to detect internal flaws and measure remaining material thickness by timing echo return.

• Measures thickness loss from corrosion
• Can detect subsurface flaws not visible externally
• Requires a couplant between the transducer and part surface

Memory trick: 'Ultrasonic bounces sound to measure how thin it's gone.'

The minimum distance from the center of a rivet hole to the edge of a sheet, used to prevent the sheet from cracking or the rivet from pulling through under load.

• Standard minimum edge distance = 2 x rivet diameter (2D)
• Flush/countersunk rivets typically require greater edge distance (2.5D)
• Insufficient edge distance is a common cause of rivet repair failure

Memory trick: 'Two Diameters to the Door' — edge distance is always 2x the rivet size.

A valve that converts tiller (or rudder pedal) input into hydraulic flow directed to steering actuators to turn the nose wheel.

• Mechanically linked to the cockpit tiller
• Meters flow direction and rate to steering cylinders
• Failure causes no nose wheel response despite normal pressure
• Distinct from shimmy dampers and sequence valves

Memory trick: Tiller talks, metering valve translates, cylinder turns.

A dimensional reference system that measures distance in inches aft of a zero datum point along the aircraft's longitudinal axis, used to precisely locate structure and equipment.

• Datum is a fixed reference point, often the nose or a point ahead of it.
• Works together with Buttline (lateral) and Waterline (vertical) systems.
• Used in maintenance manuals to pinpoint repair or inspection locations.

Memory trick: 'Station' = distance down the runway of the fuselage (fore-aft)

A castellated nut has slots cut into its top so a cotter pin can be inserted through the drilled bolt shank and nut, mechanically preventing the nut from backing off.

• Requires a bolt with a drilled shank
• Cotter pin prongs are bent to secure it in place
• Common on clevis bolts and landing gear bolts
• Provides positive mechanical lock, unlike friction-based locknuts

Memory trick: Castle nut needs a pin guard at its gate — the cotter pin.

A bridge circuit using a resistance-bulb (RTD) sensor in one leg; as sensor resistance changes with temperature, the bridge becomes unbalanced and deflects a galvanometer-type gauge proportional to temperature.

• RTD resistance increases with temperature
• Bridge imbalance current drives the temperature gauge needle
• Added resistance from corrosion or bad connections mimics higher temperature reading

Memory trick: More resistance, bridge tips toward 'hot.'

A valve that automatically shuts off flow to non-essential hydraulic subsystems when system pressure drops, ensuring essential systems (like flight controls) retain adequate flow.

• Protects essential systems during low pressure/flow conditions
• Common in systems shared by flight controls and landing gear/flaps
• Reopens automatically once pressure is restored

Memory trick: Priority valve = 'VIP line' — flight controls cut to the front when pressure is low.

A fully-submerged reference probe in a capacitance fuel quantity system that measures fuel dielectric constant to correct readings for temperature/density variations.

• Always fully immersed regardless of fuel level
• Compensates for changes in fuel dielectric constant with temperature
• Improves accuracy of capacitance-type fuel quantity indication

Memory trick: Compensator tube is the system's built-in thermometer for fuel density.

A heat treatment process that softens work-hardened aluminum alloys by heating to approximately 775°F, holding, then slow cooling, restoring maximum workability.

• 2024 aluminum annealing temp ≈ 775°F (413°C)
• Slow controlled cooling (furnace cool) required
• Fully softens metal for extensive forming
• Opposite of solution heat treatment, which quenches rapidly to harden

Memory trick: Anneal is slow like a turtle — heat gently, cool gently.

A rivet that can be fully installed from one side of a structure using a pull mandrel, used where the opposite side is inaccessible.

• Common brands: Cherry rivets, Cherrylock
• Mandrel is pulled and breaks off after forming the shop head
• Not always approved as a structural repair rivet without specific data

Memory trick: 'Blind Access, Blind Rivet' — one side only calls for a blind rivet.

The first digit of a wrought aluminum alloy designation identifies the principal alloying element, allowing quick identification of an alloy's general properties.

• 1xxx = pure aluminum (99%+)
• 2xxx = copper (high strength, e.g., 2024)
• 6xxx = magnesium+silicon (good formability, e.g., 6061)
• 7xxx = zinc (highest strength, e.g., 7075)

Memory trick: Seven-Up has Zinc-y fizz — 7xxx means Zinc for max strength.

A pin on multiple-disc brakes that shows lining wear by how far it protrudes when the brake is applied.

• Pin protrudes less as linings wear
• Flush or below-limit position means replacement needed
• Always checked with brake applied, per manufacturer's chart

Memory trick: Flush pin = finished brake

A device that automatically adjusts generator field current to maintain a constant output voltage regardless of changes in generator speed or load.

• Carbon pile regulators use pressure to vary resistance in the field circuit
• Vibrating point (vibrator-type) regulators rapidly open/close field circuit
• Works with reverse current relay and overvoltage relay for full protection

Memory trick: Regulator rides the field current like a governor keeping voltage steady

Corrosion that occurs when two dissimilar metals are in electrical contact in the presence of an electrolyte, causing accelerated attack of the more anodic metal.

• Requires dissimilar metals, electrical contact, and an electrolyte
• Aluminum near stainless steel or copper is a common example
• Prevented by isolating dissimilar metals with sealant, primer, or non-conductive spacers

Memory trick: 'Galvanic = two metals shake hands and one gets hurt.'

Specific structural locations designated by the manufacturer that are reinforced to safely support the aircraft's weight during jacking operations.

• Located per the aircraft maintenance manual
• Reinforced with additional structure to handle concentrated loads
• Improper jacking location can cause permanent structural damage

Memory trick: Jack only where the book says - not where it looks strong

A canister of silica gel crystals placed downstream of a pneumatic air compressor to absorb moisture from compressed air, preventing icing and corrosion.

• Silica gel turns from blue to pink when saturated
• Prevents ice formation in pneumatic lines at altitude
• Located downstream of compressor, upstream of storage bottle

Memory trick: Blue crystal blush turns pink when it's had its fill of water

Toe-in occurs when front tire measurements are smaller than rear measurements (tires point inward); toe-out occurs when front measurements are larger, indicating tires point outward at the front.

• Measured by comparing front vs rear distance between wheels/marks at axle height
• Toe-out: rear measurement greater than front
• Improper alignment causes abnormal tire wear and handling issues

Memory trick: 'Toe-OUT points tires out like a duck, rear measurement is bigger'

A continuous hinge consisting of two long leaves joined by a single pin running the entire length, used on cowlings and access panels for even load distribution.

• Continuous full-length hinge pin
• Distributes load evenly along the joint
• Common on cowlings, doors, and control surfaces

Memory trick: Piano hinge = keys in a row, one long pin holding it together

Drift of a directional gyro caused by the earth's rotation, occurring at a rate of 15° × sin(latitude) per hour, requiring periodic realignment with the magnetic compass.

• Drift rate depends on latitude: 15° × sin(latitude) per hour
• Zero drift rate at the equator, maximum at the poles
• Pilots must periodically reset the DG to the magnetic compass heading

Memory trick: Sine of latitude scales how fast the earth 'steals' your gyro's heading.

In a series circuit, the same current flows through all components, and each resistor drops a voltage proportional to its resistance.

• Current is constant throughout a series circuit
• Voltage drop = I × R for each resistor
• Sum of all voltage drops equals source voltage
• Total resistance = sum of individual resistances

Memory trick: Think of a single-lane road: the same traffic (current) passes every tollbooth (resistor), each charging its own toll (voltage drop).

A hydraulic line fitting containing internal check valves in both halves that automatically close when the fitting is disconnected, minimizing fluid loss and air entry during component removal.

• Used where components are frequently removed for maintenance
• Both halves seal independently upon separation
• Reduces need to drain system or bleed excessive air after reconnection

Memory trick: Quick-disconnect = 'self-closing garden hose nozzle' — no drip when you pull it apart.

A composite curing technique where a sealed plastic bag is placed over the layup and air is evacuated, allowing atmospheric pressure to compact the plies and remove voids and excess resin during cure.

• Uses atmospheric pressure (~14.7 psi) for compaction
• Removes trapped air voids and excess resin
• Often combined with heat blankets or autoclave for cure
• Improves fiber-to-resin ratio and part strength

Memory trick: Vacuum squeezes the sandwich flat like a food-saver bag.

Internal check valves in a manual auxiliary hydraulic pump that direct fluid flow on intake and discharge strokes, allowing pressure to build with each stroke.

• Two check valves per pump: intake and discharge
• Used for ground servicing and emergency system operation
• A stuck-open check valve causes fluid recirculation with no pressure rise

Memory trick: Wobble pump check valves = 'one-way doors' — stuck open means fluid sloshes with no progress.

The tendency of a spinning gyroscope to maintain the alignment of its axis of rotation in a fixed direction in space unless acted upon by an external force.

• Basis for attitude and heading indicators
• Two-degree-of-freedom gyros used for rigidity applications
• Precession is the error resulting from applied outside torque

Memory trick: Rigid gyro stands still in space like a stubborn statue

A cold-working process in which a part's surface is bombarded with small round media to induce compressive residual stress and improve fatigue resistance.

• Commonly used on landing gear, springs, and other highly stressed steel parts
• Compressive stresses resist crack initiation from cyclic (fatigue) loading
• Performed after final machining, often before plating

Memory trick: Shot peening pounds in a protective compression shield

A system with a valve that connects fuel lines between engines so fuel from either tank can supply either engine, commonly used during single-engine or pump-failure operations.

• Distinct from fuel transfer systems used to balance tank quantities
• Typically manually selected by the pilot
• Critical for extending range or managing failures in multi-engine aircraft

Memory trick: Crossfeed lets one tank feed either engine like a shared straw.

The Structural Repair Manual contains charts and criteria defining the maximum dent, scratch, or crack dimensions that can remain in service without repair (negligible damage) versus damage requiring repair.

• Found in the manufacturer's SRM
• Specifies limits by structure zone, depth, length, and location
• Guides decision: no action, blend-out, or repair
• Exceeding limits requires an engineered repair or manufacturer approval

Memory trick: When skin gets dinged, check the SRM before you sing 'it's fine' or 'fix it.'

Structural wood such as Sitka spruce must meet specific grading standards for grain slope, moisture content, and defects before use in aircraft repair.

• Maximum slope of grain is 1 in 15
• Acceptable moisture content is typically 12 percent or less
• Wood must be free of decay, compression wood, and excessive knots

Memory trick: 'Fifteen or finer, or the spar's a liar.'

When the pitot tube is blocked but its drain hole remains open, airspeed indication behaves like an altimeter, rising during climb and falling during descent due to changing static pressure.

• Trapped pitot pressure stays constant
• Static pressure changes normally with altitude
• Airspeed indicator falsely mimics altitude changes

Memory trick: Blocked pitot with open drain turns your airspeed dial into a fake altimeter