FAA Aviation Mechanic Airframe (AMA) flashcards

Issued under 14 CFR 21.197/21.199 to allow an aircraft that does not currently meet airworthiness requirements to be flown to a location for repairs, alterations, maintenance, or storage, after an inspection confirms safety for that specific flight.

• Requires an inspection to confirm safe-for-flight condition, not a full annual
• Permit specifies conditions/limitations for the flight (e.g., route, weight, crew)
• Issued by FAA or designated representative (e.g., DAR)

Memory trick: Ferry permit = 'fit enough for one flight,' not fully fixed

A cockpit lighting system that shows whether each landing gear is up-and-locked, down-and-locked, or in transit.

• Green light = down and locked
• Red/amber light = in transit or unsafe
• No light (in most systems) = up and locked
• Driven by mechanical or electrical downlock/uplock switches

Memory trick: Green means go-ahead-land, red means retry.

A quick-drain valve located at the lowest point of a fuel tank used to remove water and sediment contamination.

• Located at tank low points
• Checked during preflight and inspections
• Prevents water contamination from reaching the engine

Memory trick: Water sinks, sumps drink it out before it hits the engine.

A DC motor with field and armature windings in series, producing very high starting torque at low speed, ideal for engine cranking.

• Field and armature current are equal
• Highest torque at zero/low speed
• Speed increases greatly if load is removed (risk of overspeed)

Memory trick: Series motor = 'muscle at zero speed' for cranking a stubborn engine.

A backup braking system using stored compressed air or nitrogen, released through a metering/relief valve directly to the brakes when normal hydraulic braking fails.

• Stores gas in a charged bottle
• Bypasses failed hydraulic power system
• Metering valve controls pressure applied to brakes
• Provides braking capability without normal hydraulic power

Memory trick: When hydraulics quit, compressed air steps in to stop.

Pump displacement per revolution equals volumetric flow rate divided by pump rotational speed, after converting flow to consistent volume units.

• 1 gallon = 231 cubic inches
• Displacement (in³/rev) = flow (in³/min) ÷ speed (rpm)
• Fixed-displacement pumps have constant displacement per revolution

Memory trick: Gallons to inches, then divide by spins — that's the pump's gulp per turn.

Aircraft wire gauge must be selected based on both current-carrying capacity and allowable voltage drop, which increases with wire length and current draw.

• Wire size charts factor in current, length, and allowable voltage drop
• Longer wire runs require larger gauge wire to limit voltage drop
• Excessive voltage drop can cause equipment malfunction or dim lighting
• Ambient temperature also affects a wire's continuous current rating

Memory trick: Think of a long garden hose — the longer it is, the more pressure (voltage) is lost by the time water (current) reaches the end.

An NDT method using colored or fluorescent liquid dye to detect surface-breaking defects in nonporous, non-magnetic materials.

• Works on aluminum, magnesium, titanium, and other nonferrous metals
• Steps: clean, apply penetrant, remove excess, apply developer, inspect
• Cannot detect subsurface flaws, only surface-breaking ones

Memory trick: Dye stains the surface secret; magnets grab only iron

A control surface tab linked to the fixed airframe structure that automatically deflects opposite to the primary control surface, reducing the pilot's required control force.

• Linked to fixed structure, not the cockpit control
• Moves automatically opposite the control surface
• Reduces pilot control force aerodynamically

Memory trick: Balance tab is 'tied to the wing' — it swings opposite automatically to balance the load

A low-resistance electrical strap connecting metal components of an aircraft to equalize electrical potential, reduce radio interference, and provide a path for fault or lightning current.

• Provides low-resistance path between structural components
• Reduces static charge buildup differences between parts
• Helps prevent radio frequency interference (RFI)
• Different function from static discharge wicks, which release static charge to the air

Memory trick: Bonding jumpers are the 'handshake' between metal parts, keeping them at equal electrical potential.

A directional control valve with four ports that routes pressurized fluid to one side of a double-acting actuator while opening the opposite side to return.

• Controls direction of double-acting actuators
• Has pressure, return, and two actuator ports
• Neutral position often blocks both actuator ports to hold position

Memory trick: Four-way valve = four doors, only two open at once in opposite flow.

The compressive stress at the contact surface between a fastener and the material it passes through, calculated as load divided by fastener diameter times material thickness.

• Formula: Bearing Stress = Load / (Diameter x Thickness)
• Excess bearing stress can elongate rivet holes or crack sheet edges
• Different from shear stress, which acts across the fastener cross-section

Memory trick: 'Bearing = Load over the Footprint' — diameter times thickness is the contact patch.

A maintenance inspection approach that divides the aircraft into defined zones, with each zone inspected as a unit covering all systems and structures within it.

• Common in air carrier Continuous Airworthiness Maintenance Programs (CAMP)
• Each zone has its own checklist covering structure, systems, and wiring
• Helps ensure comprehensive coverage without duplicating effort

Memory trick: 'Zonal = zip through Zones one at a time.'

A spring-loaded fastener that locks with a 90-degree turn of a screwdriver, used for quick removal and installation of access panels and cowlings.

• Quarter-turn engagement/disengagement
• Receptacle remains attached to structure
• Ideal for frequently accessed panels

Memory trick: Dzus = 'do it in a quarter-second' turn to open

A mandatory FAA-issued directive correcting an unsafe condition in an aircraft, engine, propeller, or appliance; compliance is legally required and tracked in maintenance records.

• ADs are enforceable under 14 CFR Part 39 and mandatory for all affected aircraft
• Recurring ADs must be complied with at each specified interval, not just once
• Overdue AD compliance makes the aircraft unairworthy regardless of other inspection status

Memory trick: An AD is a law, not a suggestion — miss the deadline and you're grounded

A procedure to minimize magnetic compass deviation by adjusting the N-S compensator on a north heading and the E-W compensator on an east heading, then recording residual deviation on other headings.

• N-S compensator adjusted while heading north
• E-W compensator adjusted while heading east
• Remaining headings are recorded, not adjusted, on the deviation card

Memory trick: North fixes North-South screw, East fixes East-West screw

The standard head angle for countersunk aircraft rivets (e.g., MS20426) that must match the countersink or dimple angle in the skin for proper flush installation.

• Standard flush rivet angle is 100 degrees
• Must match countersink/dimple angle in sheet
• Used to reduce aerodynamic drag on skin surfaces
• Contrasts with 82-degree universal (protruding) head angle

Memory trick: Flush needs 100 to lie flat and smooth.

Laboratory particle counting of hydraulic fluid identifies solid contaminants that can abrade close-tolerance components like servo valves and pump pistons, leading to premature wear and failure.

• Particles in the 5-15 micron range match critical component clearances
• Ferrous metal particles suggest active internal component wear
• Regular fluid sampling supports condition-based maintenance

Memory trick: Tiny grit in tight gaps grinds parts to dust

AC 43.13-1B specifies cable rejection based on the number of broken wires counted within one cable lay length, with stricter limits near terminals, fittings, and pulleys where fatigue concentrates.

• Criteria vary by cable construction (e.g., 7x7 vs 7x19)
• Broken wires near end fittings are more critical than in free sections
• Cable should also be checked for corrosion, wear, and kinking

Memory trick: Count breaks 'per lay,' not the whole way

An instrument that displays rate of climb or descent by measuring the rate of change of static pressure using a diaphragm and a calibrated restricted leak.

• Diaphragm connects directly to static pressure and responds instantly
• Case pressure changes slowly through a calibrated leak
• Pressure differential between diaphragm and case indicates rate, displayed in feet per minute

Memory trick: Diaphragm reacts fast, case leaks slow — that lag shows how quick you go.

An FAA-approved fabric covering process (e.g., Ceconite, Poly-Fiber, Stits) that must be followed in its entirety, using only the specified materials and procedures.

• STC approval covers the entire process, not individual materials
• Mixing processes/materials voids the approval
• Common systems include Ceconite, Poly-Fiber, and Stits

Memory trick: 'One STC, one recipe—no substitutions allowed.'

A backup method of lowering landing gear by mechanically releasing uplocks so gravity and airflow extend and lock the gear when hydraulic power fails.

• Bypasses normal hydraulic actuators
• May be assisted by a separate nitrogen or spring-loaded bottle
• Requires manual downlock verification after use

Memory trick: Free-fall gear drops like an anchor when the hydraulics quit

A magnetic compass error caused by dip where, when turning from a heading near north, the compass initially indicates a turn opposite to the actual direction of turn.

• Caused by magnetic dip acting on the pendulously mounted compass card
• Greatest near north/south headings, minimal near east/west
• Remembered by mnemonic 'ANDS': Accelerate North, Decelerate South

Memory trick: ANDS: Accelerate North, Decelerate South — and turns from North Lag, from South Lead

Visual and mechanical inspection of a crimped wire terminal to verify proper strand condition, indent location, and insulation support before installation.

• Terminal barrel size must match wire gauge (color-coded)
• No cut, broken, or missing strands allowed at crimp point
• No bare copper should extend beyond the terminal barrel

Memory trick: Broken strands = broken connection — cut it off and start over.

An inspection performed to verify that an aircraft, component, or alteration conforms exactly to approved engineering data, drawings, or specifications.

• Used for major alterations, repairs, and new production items
• Confirms compliance with approved data before return to service
• Often required before FAA Form 337 sign-off
• Distinct from recurring scheduled maintenance inspections

Memory trick: Conformity = 'confirm it matches' the blueprint before flight

Inspection of fuel tank access panels and seams for cracked, lifted, or deteriorated sealant that could allow fuel leakage or contaminant intrusion.

• Cracked sealant can cause fuel leaks, a serious fire hazard
• Moisture intrusion through failed seals promotes internal corrosion
• Sealant repairs must use approved fuel-resistant sealant per maintenance manual

Memory trick: Broken sealant is a leaky secret door for fuel and moisture

Approved methods (single-wrap, double-wrap, or clip-locking) used to prevent a turnbuckle barrel from rotating and loosening a control cable after rigging.

• Single-wrap: one wire, minimum 4 wraps
• Double-wrap: two wires, minimum 3 wraps each
• Clip-locking: mechanical spring clips, no wire needed

Memory trick: Double-wrap = Double the wires, Double the safety.

The percentage difference between a relief valve's initial cracking pressure and its full-flow (fully open) pressure, calculated as (full-flow − crack) ÷ crack × 100.

• Crack pressure is where the valve first begins to open
• Full-flow pressure is where the valve is fully open
• Differential/spread must be within the manufacturer's tolerance during checks

Memory trick: Divide the gap by the starting point to get the percent spread

A backup valve independent of the outflow valve that automatically opens to prevent cabin differential pressure from exceeding structural limits.

• Purely mechanical, spring-loaded backup
• Protects fuselage from overpressure
• Separate from primary outflow valve

Memory trick: Safety valve = the fuselage's seatbelt against too much push

A hydraulic reservoir design that uses regulated air (e.g., engine bleed air) ducted directly into the reservoir's air space above the fluid to maintain positive pressure at the pump inlet.

• Prevents pump cavitation, especially at altitude
• Contrasts with bootstrap reservoirs, which use a hydraulic piston instead of direct air
• Requires a regulated air source and pressure regulating valve

Memory trick: Air-pressurized: air blows straight into the tank; bootstrap: fluid pressure pulls its own bootstraps

A fuel additive that increases the electrical conductivity of jet fuel to allow rapid dissipation of static charge generated during high-flow refueling.

• Common trade name is Stadis 450
• Prevents static spark hazards during fast fueling
• Different in purpose from FSII (anti-icing) and biocides

Memory trick: 'SDA Shields against Dangerous Arcs.'

The relationship between voltage, current, and resistance in a DC circuit, expressed as E = I × R.

• E = voltage in volts
• I = current in amps
• R = resistance in ohms
• Rearranged forms: R = E/I, I = E/R

Memory trick: Picture a triangle: cover R, and E over I remains, like covering a slice of pie.

Both create a depression for a flush rivet head, but dimpling stretches/forms thin sheet metal (no material removed) while countersinking cuts away material and is used on thicker sheet.

• Dimpling used when skin thickness is less than the rivet head height.
• Countersinking used on thicker skins, typically 0.040 inch or greater.
• Coin dimpling and radius dimpling are common dimpling methods.

Memory trick: Thin skin? Dimple it, don't cut it — 'Dimple for the Delicate'

At constant temperature, the pressure of a gas is inversely proportional to its volume: P1V1 = P2V2.

• Used to calculate final pressure when air bottle discharges into larger volume
• Applies to emergency pneumatic gear extension and other compressed air systems
• Assumes constant temperature (isothermal process)

Memory trick: Bigger space, same gas, lower pressure — squeeze law reversed.

Instruments such as the attitude and heading indicators that use airflow from an engine-driven vacuum pump to spin an internal gyro rotor at operating speed.

• Vacuum pump draws air through the instrument to spin the gyro
• Low suction causes sluggish or tumbling gyro response
• Turn coordinator is typically electrically powered instead

Memory trick: Vacuum sucks air to spin the gyro wheel

Trapped air is compressible and causes spongy, delayed, or erratic operation of hydraulic actuators, unlike the essentially incompressible hydraulic fluid.

• Systems must be bled after component replacement
• Air causes spongy brakes/actuator response
• Bleeding removes trapped air via bleed valves

Memory trick: Air is a sponge, fluid is a rock — bleed the sponge out.

Aluminum alloys must be quenched within 10 seconds of removal from the solution heat treating furnace to prevent premature precipitation at grain boundaries.

• Maximum quench delay: 10 seconds
• Delay risk: loss of corrosion resistance and strength
• Followed by natural or artificial aging (T4/T6)

Memory trick: 10 seconds: count to ten, then dunk it in!

A tube extending upward from the bottom of a hydraulic reservoir through which the normal system draws fluid, leaving a reserve below its opening for the emergency system.

• Normal system draws from top of standpipe
• Emergency system draws from reservoir bottom
• Protects against total fluid loss from a normal-system leak

Memory trick: Standpipe = savings account fluid the normal system can't touch.

A required test of the static pressure system, altimeter, and automatic altitude reporting equipment every 24 calendar months for IFR operations, per Part 43 Appendix E.

• Applies to aircraft operated under IFR in controlled airspace
• Interval is 24 calendar months, same as transponder test under 91.413
• Test must be performed by an appropriately certificated repair station or the manufacturer

Memory trick: Altimeter and transponder are 24-month twins

Components with a mandatory retirement life (hours, cycles, or calendar time) established by the manufacturer or airworthiness limitations section, requiring individual record tracking separate from the airframe.

• Common on turbine engine rotating parts (disks, blades) with cycle limits
• Records must show time/cycles since new (TSN) and since overhaul (TSO) if applicable
• Failure to track and replace on time results in an unairworthy condition

Memory trick: Life-limited parts carry their own personal odometer, not the airframe's

A test instrument that applies a high DC test voltage to measure very high resistance values, used to check the insulation resistance of wiring and windings.

• Applies test voltages far higher than a standard multimeter
• Measures resistance in megohms
• Used before energizing new or repaired wiring installations

Memory trick: Megger = 'Mega volts to catch mega problems' in insulation.

A hydraulic valve that controls the order of operation between two actuators, such as gear doors and gear struts, during retraction/extension.

• Ensures doors open before gear retracts
• Prevents structural interference between doors and gear
• Common in complex retractable gear hydraulic systems

Memory trick: Sequence valve is the traffic cop: doors first, then gear

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

• Farther apart on the galvanic series = greater corrosion risk
• Prevention: isolate metals with sealant, primer, or nonmetallic barrier
• Moisture acts as the electrolyte completing the circuit

Memory trick: 'Keep Metals Apart, Keep Corrosion at Bay' — isolate with a barrier.

The vapor space intentionally left above the liquid fuel in a tank to allow for thermal expansion of the fuel and to accommodate fuel/air vapor mixture.

• Tanks are not filled to 100% capacity
• Prevents overpressure/venting from thermal expansion
• Also the space where OBIGGS introduces inert gas

Memory trick: 'Ullage is the extra room fuel needs to stretch when it's hot.'

The spar cap is the top and bottom member of a wing spar that carries tension and compression bending loads, while the spar web between the caps carries shear loads.

• Located at top and bottom of the spar
• Carries bending (tension/compression) loads
• Spar web carries shear between the caps
• Often thicker/heavier material than the web

Memory trick: Cap on top and bottom takes the bend; web in the middle takes the shear.

The directional alignment of metal fibers from the rolling process, which affects bend strength and cracking tendency.

• Bends across the grain resist cracking better than bends parallel to grain
• Minimum bend radius charts assume bending across the grain
• Bending parallel to grain requires a larger bend radius to avoid cracking

Memory trick: Bend across the grain like breaking a log across its rings, not along them

An empty vent-system chamber, usually near the wingtip, that catches fuel displaced by expansion or sloshing before it reaches the vent outlet, then drains it back into the main tank.

• Not part of usable fuel volume
• Prevents fuel loss through vent outlet
• Drains collected fuel back to main tank

Memory trick: Surge tank = 'catch-all' for fuel surges before it escapes

An IA, held by an experienced A&P mechanic per 14 CFR 65.91-65.95, adds the authority to perform/approve annual and progressive inspections and to approve major repairs/alterations for return to service.

• Requires 3 years of experience as an A&P before eligibility
• Must be renewed annually by meeting activity requirements
• 100-hour inspections and routine maintenance do not require an IA

Memory trick: IA = 'I Approve' major repairs and annuals

A hydraulic reservoir pressurized internally by a floating piston acted on by system hydraulic pressure, ensuring adequate pump inlet pressure at altitude.

• Uses internal piston, not external air
• Self-pressurizing from system pressure
• Prevents pump cavitation at altitude

Memory trick: Bootstrap 'pulls itself up' using its own system pressure.