FAA Mechanic Airframe (AMA) Knowledge Test, Practice Exams

A 'smoking rivet' with a dark trail or black ring around its head is a sign of what defect?

1. A loose or working rivet that is moving in its hole ✓
2. A rivet driven with excessive shop-head height
3. A rivet installed with the wrong alloy code

Why: A smoking rivet, indicated by a dark smudge or black ring trailing from the head, is a sign of a loose or working rivet and is a common sheet-metal defect. FAA-H-8083-31B ch.4.

What does the green arc on an instrument such as an airspeed indicator or tachometer indicate?

1. The normal operating range ✓
2. A caution range that requires monitoring
3. A limit that must never be exceeded

Why: The green arc indicates the normal operating range of the instrument; yellow is the caution/precautionary range and a red line is a limit not to be exceeded. FAA-H-8083-31B ch.10.

What maintains normal windshield temperature control in an electrically heated windshield system?

1. Thermal overheat switches.
2. Thermistors. ✓
3. Manually-controlled rheostat.

Why: Thermistors sense and maintain normal windshield temperature in an electrically heated windshield system (overheat switches are the backup limit). FAA-H-8083-31B ch.15.

Airborne weather radar detects what ahead of the aircraft?

1. Precipitation (and thereby storm cells), by transmitting a beam and receiving its reflection ✓
2. Other aircraft, by interrogating their transponders per the applicable maintenance manual per the applicable maintenance manual
3. The ILS glideslope angle to the runway

Why: Weather radar transmits a directional beam ahead of the aircraft and displays the reflected returns from precipitation, letting the crew locate and avoid thunderstorm cells and areas of heavy rain. FAA-H-8083-31B ch.11.

The global positioning system (GPS) determines the aircraft's position by what principle?

1. Measuring the time/distance to multiple satellites and computing position by trilateration ✓
2. Measuring the bearing to two VOR ground stations per the applicable maintenance manual per the applicable maintenance manual
3. Timing the echo of a radar pulse off the ground

Why: GPS receivers compute position by measuring the range to several satellites (from signal travel time) and solving for latitude, longitude, and altitude by trilateration; four or more satellites give a 3D fix. FAA-H-8083-31B ch.11.

When a Service Bulletin is incorporated by reference into an Airworthiness Directive, what is its status?

1. It becomes mandatory, because the AD makes compliance with the referenced SB required ✓
2. It remains entirely optional, because service bulletins are always purely advisory in nature
3. It applies only to aircraft that happen to be operated commercially for hire under part 91

Why: When all or part of a Service Bulletin is incorporated into an AD, compliance with that content becomes mandatory because the AD itself is mandatory. 14 CFR 39.13.

Inspection requirements for large airplanes (over 12,500 lb) are addressed under which paragraphs of 14 CFR 91.409?

1. Paragraphs (e) and (f) ✓
2. Paragraphs (a) and (b)
3. Paragraph (d) only

Why: For large airplanes (over 12,500 lb), the inspection requirements of 14 CFR 91.409 paragraphs (e) and (f) apply (e.g., an approved inspection program), rather than the annual/100-hour of (a)/(b). 14 CFR 91.409.

Who may perform a progressive inspection, and under what condition?

1. A certificated A&P mechanic, as long as supervised by a mechanic holding an Inspection Authorization ✓
2. Only the aircraft manufacturer's own factory field service representative is ever authorized to perform this inspection
3. Any private pilot who owns the aircraft may perform it themselves without any supervision at all

Why: A certificated A&P mechanic may perform a progressive inspection as long as they are supervised by a mechanic holding an Inspection Authorization. 14 CFR 91.409(d).

A magnetic chip detector in a helicopter transmission is used to do what?

1. Capture and signal metal particles in the oil, indicating internal gear/bearing wear ✓
2. Measure the transmission oil temperature per the applicable maintenance manual
3. Change engine rpm to rotor rpm

Why: A magnetic chip detector attracts ferrous particles carried in the transmission/gearbox oil; accumulating chips (or an electrical chip warning) indicate internal wear and prompt further inspection. FAA-H-8083-31B ch.2.

Compared with a hydraulic system, an aircraft pneumatic system typically lacks which components?

1. Reservoirs and hand pumps, because the air is exhausted to the atmosphere rather than returned ✓
2. Any relief valves or filters, which are never used in pneumatic systems per the applicable maintenance manual
3. Actuators and lines, because pneumatics move nothing mechanically

Why: Pneumatic systems are similar to hydraulics but do not use reservoirs or hand pumps: the working air is compressed and, after use, exhausted to the atmosphere rather than recirculated. FAA-H-8083-31B ch.12.

After swaging a terminal onto a cable, the terminal should be inspected to confirm what?

1. That it is free of die marks and splits, is not out of round, and the cable has not slipped ✓
2. That the terminal barrel is filled flush with solder to seal the cut cable end against fraying
3. That at least three individual cable strands are left visible protruding past the barrel end

Why: After swaging, inspect the terminal so it is free of die marks and splits and not out of round, check for cable slippage at the tape mark, and gauge the shank diameter with a go/no-go gauge. FAA-H-8083-31B ch.2.

What is the bead seat area of an aircraft wheel?

1. The critical area where the tire bead contacts the wheel rim, prestressed for the tensile loads of landing ✓
2. The central hub bore that accepts the axle and wheel bearings per the applicable maintenance manual
3. The vent hole through which the tire is inflated and deflated

Why: The bead seat is where the tire actually contacts the wheel; it is a critical, highly stressed area, typically roll-formed to prestress it with compressive stress to handle landing tensile loads. FAA-H-8083-31B ch.13.

How is an ammeter connected to measure current in a circuit?

1. In series with the circuit, so all the current flows through it ✓
2. In parallel with the load, like a voltmeter per the applicable maintenance manual
3. Across the battery terminals only

Why: An ammeter is connected in series with the circuit so the measured current flows through it; it has very low internal resistance to minimize its effect on the circuit. FAA-H-8083-31B ch.9.

The procedure of adjusting the compensating magnets to minimize magnetic compass deviation is called what?

1. Swinging the compass ✓
2. Slaving the compass per the applicable maintenance manual
3. Caging the compass

Why: Swinging the compass is the procedure of determining and compensating for deviation on a compass rose, adjusting the N-S and E-W compensating magnets in the instrument housing. FAA-H-8083-31B ch.10.

An automatic direction finder (ADF) indicates what, relative to what type of ground station?

1. The relative bearing to a non-directional beacon (NDB) transmitting in the low/medium frequency band ✓
2. The slant distance to a DME station in the UHF band
3. The glidepath angle to an ILS glideslope transmitter per the applicable maintenance manual

Why: An ADF points to a non-directional beacon (NDB), indicating the relative bearing from the aircraft's nose to the station; NDBs transmit in the low/medium frequency band. FAA-H-8083-31B ch.11.

On which landing gear arrangement is the main gear located behind the center of gravity with a small wheel under the tail?

1. The conventional (tailwheel) landing gear arrangement ✓
2. The tricycle landing gear arrangement per the applicable maintenance manual
3. The tandem landing gear arrangement

Why: The conventional (tailwheel) arrangement places the two main wheels ahead of the CG with a small tailwheel aft; the tricycle arrangement uses a nosewheel and mains behind the CG. FAA-H-8083-31B ch.13.

Why are flexible hoses (rather than rigid tubing) used in parts of a hydraulic system?

1. To connect components that move relative to each other or are subject to vibration ✓
2. Because flexible hose is always stronger than rigid metal tubing per the applicable maintenance manual
3. Because hose never needs replacement, unlike rigid tubing

Why: Flexible hose is used where components move relative to one another or where vibration would fatigue rigid tubing; rigid tubing is used for fixed runs. Hoses have a limited service life and are inspected for condition. FAA-H-8083-31B ch.12.

Why is a cracked exhaust heat exchanger (heater muff) on a reciprocating aircraft dangerous?

1. It can allow carbon monoxide from the exhaust to enter the cabin heating air ✓
2. It can raise the cabin differential pressure above its structural limit per the applicable maintenance manual
3. It can cause the outflow valve to freeze open in flight

Why: A reciprocating aircraft heats cabin air by passing it over an exhaust shroud/heat exchanger; a crack lets carbon monoxide from the exhaust leak into the cabin air — a serious, potentially fatal hazard. FAA-H-8083-31B ch.16.

During water/waste system inspection, a technician checks for what?

1. Leaks, security of tanks/lines, proper operation of valves/heaters, and correct servicing quantities ✓
2. The octane rating of the flush fluid
3. The specific gravity of the potable water according to the manufacturer's service data

Why: Water/waste inspection covers leaks, security and condition of tanks and lines, operation of valves, pumps, and line/drain-mast heaters, and correct fluid quantities, per the maintenance manual. FAA-H-8083-31B ch.16.

An oxygen cylinder due for servicing shows a greasy fingerprint near the valve. What is the correct action?

1. Remove the contamination completely before servicing, since oil/grease with oxygen is an explosion hazard ✓
2. Proceed with servicing, since a small amount of grease is harmless per the applicable maintenance manual per the applicable maintenance manual
3. Wipe it with penetrating oil to neutralize it before servicing

Why: Any oil or grease contamination on oxygen equipment must be completely removed before servicing, because hydrocarbons combined with oxygen form a dangerous fire/explosion hazard. FAA-H-8083-31B ch.16.

Smoke detectors that use a measurement of light transmissibility in the air are called

1. thermocouple devices.
2. photoelectrical devices. ✓
3. ultraviolet optical devices.

Why: Smoke detectors that measure light transmissibility (or scatter) are photoelectric devices. FAA-H-8083-31B ch.17.

Intergranular corrosion is an attack along the grain boundaries of a metal and is especially a concern in which materials?

1. Improperly heat-treated high-strength aluminum alloys such as 2014 and 7075 ✓
2. Pure copper electrical wiring together with the various brass fittings that are connected to it
3. Cadmium-plated steel fasteners of the type used throughout the airframe structure

Why: Intergranular corrosion attacks along grain boundaries and is especially a concern in improperly heat-treated high-strength aluminum alloys such as 2014 and 7075. FAA-H-8083-30B ch.8.

'Clad' (Alclad) aluminum sheet consists of what for corrosion protection?

1. A thin coating of pure aluminum bonded over the higher-strength alloy core ✓
2. A layer of zinc chromate primer baked onto the alloy surface
3. An anodized oxide film grown electrolytically on both surfaces

Why: Clad (Alclad) aluminum has a thin coating of corrosion-resistant pure aluminum rolled onto the surface of the stronger alloy core; corrosion pits in the cladding are a defect to watch for. FAA-H-8083-31B ch.4.

Under 14 CFR 91.207, an ELT battery must be replaced (or recharged) when what occurs?

1. When the transmitter has been in use for more than 1 cumulative hour, or when 50 percent of its useful life has expired ✓
2. Only when the ELT completely fails a functional test per the applicable maintenance manual according to the manufacturer's service data
3. Every 24 calendar months, regardless of use

Why: Per 14 CFR 91.207, the ELT battery must be replaced (or recharged, if rechargeable) after 1 cumulative hour of transmitter use or when 50 percent of its useful (shelf) life has expired. 14 CFR 91.207.

A 'spongy' brake pedal most commonly indicates what?

1. Air trapped in the hydraulic brake system, requiring the brakes to be bled ✓
2. Brake discs worn beyond their wear limit and needing replacement
3. Excessive hydraulic pressure from a stuck power brake valve

Why: A spongy or soft brake pedal usually indicates air trapped in the hydraulic brake lines; the system must be bled to remove the air and restore a firm pedal. FAA-H-8083-31B ch.13.

Aircraft batteries are installed in a vented box or with a ventilation system for what reason?

1. To carry away the gases produced during charging and prevent an explosive accumulation ✓
2. To keep the battery warm in cold weather
3. To increase the battery's specific gravity per the applicable maintenance manual

Why: Battery installations include a ventilation system to carry off the hydrogen (lead-acid) or other gases produced during charging, preventing an explosive accumulation and venting corrosive fumes overboard. FAA-H-8083-31B ch.9.

What certificate action is required before an aircraft is returned to service after an annual inspection?

1. Approval for return to service by a person authorized under 14 CFR 43.7, with the required record entry ✓
2. Formal reissuance of the aircraft's Airworthiness Certificate by the FAA following completion of the inspection
3. A post-maintenance test flight that is signed off in the records by any private pilot

Why: After an inspection, the aircraft must be approved for return to service by a person authorized under 14 CFR 43.7 (for an annual, an A&P with IA), documented by the required maintenance record entry. 14 CFR 91.409.

The preferred location of an ELT is

1. as far forward as possible but aft of the firewall.
2. at the lowest point possible in the fuselage.
3. as far aft as possible but forward of the empennage. ✓

Why: The preferred ELT location is as far aft as possible but forward of the empennage. FAA-H-8083-31B ch.11.

Windshield anti-icing/defogging on many aircraft is accomplished by what?

1. Electric heating elements embedded in the windshield (or warm air blown across it) ✓
2. Pneumatic de-icer boots around the windshield edge per the applicable maintenance manual
3. A slinger ring that throws glycol onto the glass

Why: Windshields are commonly anti-iced and defogged by electrically heated elements laminated into the glass (or by ducting warm air across the surface), which also improves the glass's impact resistance. FAA-H-8083-31B ch.15.

Why must bleed air used for cabin heating be temperature-controlled before entering the cabin?

1. Compressor bleed air is extremely hot and must be cooled/mixed to a safe, comfortable temperature ✓
2. Bleed air is too cold and must always be heated further before use per the applicable maintenance manual
3. Bleed air carries refrigerant that must be removed first

Why: Engine compressor bleed air is extremely hot; it must be cooled (via heat exchangers and mixing with cooler air) and temperature-regulated before it is delivered to the cabin. FAA-H-8083-31B ch.16.

Gas tungsten arc welding (GTAW, or TIG) uses which type of electrode?

1. A non-consumable tungsten electrode ✓
2. A consumable flux-coated steel electrode
3. A continuously fed aluminum wire electrode

Why: GTAW (TIG) uses a non-consumable tungsten electrode with an inert shielding gas; filler is added separately. It is commonly used for welding 4130 steel tubing. FAA-H-8083-31B ch.5.

What is the maximum angle a fairlead may deflect a control cable from a straight line?

1. 3 degrees ✓
2. 10 degrees
3. No deflection is permitted at all

Why: Fairleads (phenolic or soft aluminum) guide cables in a straight line through structure and should never deflect a cable more than 3 degrees from a straight line. FAA-H-8083-31B ch.2.

Gyroscopic flight instruments rely on which two fundamental properties of a spinning gyro?

1. Rigidity in space and precession ✓
2. Buoyancy and capillary action per the applicable maintenance manual
3. Magnetic dip and variation

Why: Gyroscopic instruments depend on rigidity in space (the spin axis tends to stay fixed) and precession (a force applied to the spinning rotor is felt 90 degrees later in the direction of rotation). FAA-H-8083-31B ch.10.

A combustion heater provides cabin heat by what means, and what is a key safety concern?

1. Burning fuel in a sealed chamber; carbon monoxide leakage and overheat must be guarded against ✓
2. Compressing ram air to raise its temperature; icing of the inlet must be prevented
3. Passing cabin air over the exhaust stacks; only excessive noise is a concern

Why: A combustion heater burns fuel in a sealed combustion chamber to heat air; because combustion is involved, carbon monoxide leakage and overheat protection (overheat switch) are key safety concerns. FAA-H-8083-31B ch.16.

What component is added to a nosewheel to damp the rapid oscillation known as shimmy?

1. A shimmy damper ✓
2. A torque tube
3. A thermal (fusible) plug

Why: A shimmy damper (a small hydraulic snubbing unit) is fitted to the nose gear to damp shimmy — the rapid side-to-side oscillation of the nosewheel at certain speeds. FAA-H-8083-31B ch.13.

What is vapor lock, and what commonly causes it?

1. Fuel vaporizing in the lines, pump, or components, interrupting flow — caused by hot fuel, low pressure, or high altitude ✓
2. Water freezing in the fuel filter, blocking flow — caused only by cold weather per the applicable maintenance manual per the applicable maintenance manual
3. Air trapped in the brake lines, causing a spongy pedal

Why: Vapor lock is a condition in which fuel (especially AVGAS) vaporizes in the lines, pump, or fuel-metering units, interrupting fuel flow; it is caused by excessively hot fuel, low pressure, and high altitude, and is prevented by boost pumps. FAA-H-8083-31B ch.14.

Which locations are prime corrosion areas warranting special attention during cable inspection?

1. Where cables pass through battery compartments, lavatories, and wheel wells ✓
2. Where cables run through the pressurized cabin at cruise altitude
3. Where cables are enclosed inside sealed wing torque boxes

Why: Special attention should be given where cables pass through battery compartments, lavatories, and wheel wells — prime areas for corrosion. FAA-H-8083-31B ch.2.

A potable water tank quantity is indicated to the crew by what?

1. A water quantity gauge/indicator, so the crew knows how much water is aboard ✓
2. The fuel quantity gauge, which is shared with the water system
3. The cabin differential pressure gauge

Why: The potable water system includes a water quantity indicator so the crew/servicing personnel know the amount of water on board and can service it as needed. FAA-H-8083-31B ch.16.

Under 14 CFR 91.411, how often must the altimeter and static pressure system be tested and inspected for IFR operations?

1. Within the preceding 24 calendar months ✓
2. Within the preceding 12 calendar months
3. Every 100 hours of flight time

Why: Per 14 CFR 91.411, for IFR flight in controlled airspace the altimeter system and static pressure system must have been tested and inspected within the preceding 24 calendar months (per 14 CFR part 43, Appendix E). 14 CFR 91.411.

How can the proper hydraulic fluid to be used in an airplane be determined?

1. By referring to the Pilot Operating Handbook.
2. By consulting the aircraft`s Type Certificate Data Sheet.
3. By consulting the aircraft manufacturer`s service manual. ✓

Why: The correct hydraulic fluid is determined from the aircraft manufacturer's service manual (and the instruction plate on the reservoir). FAA-H-8083-31B ch.12.

Mineral-based hydraulic fluid (MIL-H-5606) is identified by what color and base?

1. Dyed red, and processed from petroleum ✓
2. Dyed purple, and made from phosphate ester
3. Dyed blue, and made from water-glycol

Why: Mineral-based hydraulic fluid (MIL-H-5606) is processed from petroleum, has an odor like penetrating oil, and is dyed red; synthetic fluids may be dyed purple or green. FAA-H-8083-31B ch.12.

Two widely used continuous-loop fire detection systems are the thermistor type and the pneumatic type. Which are examples of each?

1. Thermistor: Kidde and Fenwal; pneumatic pressure: Lindberg (Systron-Donner) ✓
2. Thermistor: Lindberg; pneumatic: Kidde and Fenwal per the applicable maintenance manual
3. Thermistor: Bendix; pneumatic: Collins

Why: Continuous-loop systems include the thermistor (resistance) type such as the Kidde and Fenwal systems, and the pneumatic pressure type such as the Lindberg (Systron-Donner) system. FAA-H-8083-31B ch.17.

Aramid (Kevlar) fiber is prized for impact resistance but has which disadvantage?

1. It is weak in compression and hygroscopic, absorbing up to 8 percent of its weight in water ✓
2. It readily conducts electricity and therefore must be carefully isolated from all avionics wiring
3. It is extremely brittle and tends to shatter on even a very minor impact against the surface

Why: Aramid (Kevlar) is light, tough, and impact-resistant, but is weak in compression and hygroscopic (absorbing up to 8 percent of its weight in water), so it must be protected from moisture. FAA-H-8083-31B ch.7.

Most transport aircraft fuel quantity indicating systems measure fuel by what method?

1. Capacitance-type probes, in which the fuel acts as the dielectric between capacitor plates ✓
2. A float and mechanical linkage read directly at each tank per the applicable maintenance manual
3. Weighing the aircraft before each flight

Why: Capacitance-type fuel quantity systems use tank probes where the fuel is the dielectric between capacitor plates; as fuel level changes the capacitance changes, and the system converts it to a quantity (by mass on many transports). FAA-H-8083-31B ch.14.

Which parts of a semi-monocoque fuselage prevent tension and compression from bending the fuselage?

1. Ribs and formers.
2. Longerons and stringers. ✓
3. Bulkheads and skin.

Why: Longerons and stringers are the longitudinal members that carry the tension/compression (bending) loads of a semimonocoque fuselage. FAA-H-8083-31B ch.1.

Helicopter drive-system (transmission and shafting) inspection includes checking for what?

1. Chip detectors, oil condition/level, mounting security, and abnormal vibration or noise ✓
2. The specific gravity of the rotor blade skins per the applicable maintenance manual per the applicable maintenance manual
3. The octane rating of the transmission oil

Why: Drive-system inspection covers the transmission and drive shafts for oil level/condition, magnetic chip detectors (metal particles indicating internal wear), mount security, coupling condition, and abnormal vibration/noise. FAA-H-8083-31B ch.2.

Fuel jettisoning systems are designed so that what does not happen?

1. The dumped fuel does not impinge on or accumulate around the aircraft structure or ignition sources ✓
2. The dumped fuel is recovered and returned to the tanks per the applicable maintenance manual
3. The dump valve can be opened only on the ground

Why: Fuel dump/jettison systems are designed and located so that jettisoned fuel discharges clear of the aircraft and does not accumulate on the structure or reach ignition sources; dumping is done in flight. FAA-H-8083-31B ch.14.

What is the function of a voltage regulator in a generator/alternator system?

1. To maintain a constant system voltage by controlling the field current ✓
2. To convert the generator's AC output into DC
3. To disconnect the battery when the engine is not running

Why: The voltage regulator automatically maintains a constant system voltage by adjusting the current in the generator/alternator field circuit as load and speed change. FAA-H-8083-31B ch.9.

How does structural ice accumulation affect an aircraft's aerodynamics?

1. It increases drag and weight and reduces lift by disrupting the airflow over the wing ✓
2. It increases lift and reduces drag, improving climb performance
3. It has no aerodynamic effect as long as the engine keeps running per the applicable maintenance manual

Why: Ice buildup disrupts the smooth airflow over the wing, which increases drag, adds weight, and reduces lift — a dangerous combination that degrades performance and control. FAA-H-8083-31B ch.15.

Which of the following allows fluid to flow unimpeded in one direction but prevents fluid flow in the other direction?

1. Check valve. ✓
2. Sequence valve.
3. Relief valve.

Why: A check valve allows fluid to flow unimpeded in one direction and prevents flow in the other. FAA-H-8083-31B ch.12.

Why must fuel tank sumps be drained and checked before the first flight of the day?

1. Water is heavier than fuel and settles into the sump; draining it removes water contamination before flight ✓
2. To relieve excess fuel tank pressure that builds up overnight per the applicable maintenance manual
3. To add anti-icing additive to the bottom of the tank

Why: Water is denser than fuel and settles to the low point (sump); draining a sample from each sump before flight removes accumulated water, a key contamination check. FAA-H-8083-31B ch.14.

What is the advantage of a circuit breaker when compared to a fuse?

1. It is easily replaced.
2. It controls current flow.
3. It is resettable and reuseable. ✓

Why: A circuit breaker's advantage over a fuse is that it is resettable and reusable. FAA-H-8083-31B ch.9.

A rotating or vibrating ice-detector probe signals ice accretion by sensing what?

1. A change (such as a shift in vibration frequency or added drag) as ice builds on the probe ✓
2. A rise in the fuel temperature per the applicable maintenance manual according to the manufacturer's service data
3. A drop in cabin pressure

Why: Ice-detector probes sense ice accretion by detecting a change caused by ice on the probe — for example, a magnetostrictive probe's vibration frequency shifts as ice mass builds up — and then signal a warning. FAA-H-8083-31B ch.15.

A pneumatic system relief valve serves what purpose?

1. It prevents pneumatic system pressure from exceeding a safe maximum ✓
2. It stores the compressed gas for emergency use
3. It converts pneumatic pressure into hydraulic pressure

Why: Relief valves are used in pneumatic systems to prevent pressure from exceeding a safe maximum, protecting the components downstream. FAA-H-8083-31B ch.12.

What is the purpose of a stall strip or stall fence on a wing (an 'other aerodynamic wing feature')?

1. To control the spanwise progression or onset of the airflow separation (stall) across the wing ✓
2. To increase the wing's internal fuel tank capacity by sealing off the leading-edge structural cavity
3. To route and carry the flight-control cables neatly through the internal wing structure

Why: Additional aerodynamic features such as stall strips and wing fences control where and how the wing stalls (managing spanwise flow and stall progression) for safer handling. FAA-H-8083-31B ch.2.

Which of the following is a recognized special (conditional) inspection?

1. A lightning-strike inspection ✓
2. A daily preflight walk-around
3. A 100-hour inspection

Why: Special (conditional) inspections are triggered by unusual events — hard/overweight landing, severe turbulence/over-G, and lightning strike — each following the manufacturer's specific inspection details. FAA-H-8083-31B ch.2.

A key part of anti-ice/de-ice system maintenance for a thermal (bleed air) system is checking what?

1. Ducts and valves for leaks and correct operation, since a leak or stuck valve can cause overheat or failure to anti-ice ✓
2. The specific gravity of the boot rubber per the applicable maintenance manual according to the manufacturer's service data
3. The rain repellent reservoir level

Why: Thermal anti-ice maintenance includes inspecting the bleed air ducts and control valves for leaks and proper operation; a leak or a stuck valve can overheat structure or leave a surface unprotected. FAA-H-8083-31B ch.15.

Which of these is a secondary/auxiliary control surface rather than a primary control?

1. A wing flap ✓
2. An aileron
3. An elevator

Why: Secondary/auxiliary surfaces include flaps, slats, spoilers, and the various tabs; the primary controls are the ailerons, elevator, and rudder. FAA-H-8083-31B ch.2.

Which rivet alloy must be kept refrigerated ('ice box') and driven soon after removal because it hardens by age at room temperature?

1. The 2024-T (DD) rivet, driven in the 'W' condition ✓
2. The 2117-T (AD) rivet, driven in the 'as-received' condition
3. The 1100 (A) rivet, driven after annealing

Why: The 2024-T4 (DD) rivet is too hard to drive as received, so it is solution heat-treated and stored frozen ('ice box'), then driven in the 'W' condition before it age-hardens. FAA-H-8083-31B ch.4.

On a vacuum toilet, the flush is initiated when the flush control opens a valve to what?

1. The waste tank/vacuum, so the pressure differential draws the bowl contents to the tank with a rinse of water ✓
2. The potable water tank, filling the bowl completely as noted in the manufacturer's instructions
3. The cabin, venting the bowl to cabin pressure

Why: Pressing flush on a vacuum toilet opens the flush valve to the waste tank (under vacuum); the differential pressure rapidly draws the bowl contents into the tank while a small charge of rinse water cleans the bowl. FAA-H-8083-31B ch.16.

Which are common defects found in composite laminates?

1. Delamination, disbond, resin starvation, and resin richness ✓
2. Intergranular corrosion, exfoliation, and stress corrosion
3. Work hardening, case hardening, and grain growth

Why: Common composite defects include delamination, disbond, resin starvation, resin richness, wrinkles, ply bridging, and impact damage. FAA-H-8083-31B ch.7.

A fire extinguishing system's discharge indicators typically show what to maintenance personnel?

1. Whether the system discharged normally (crew-commanded) or thermally (from overheat), via colored disks ✓
2. The remaining flight hours before the next inspection per the applicable maintenance manual
3. The engine oil pressure at the time of discharge

Why: Discharge indicators (colored disks at the bottle) tell maintenance whether the bottle discharged normally from a crew command or thermally from an over-temperature; this guides the corrective action. FAA-H-8083-31B ch.17.

The potable water system on a transport aircraft supplies water to what?

1. The lavatories and galleys (for washing and drinking/food service) ✓
2. The engine fire extinguishing bottles according to the manufacturer's service data
3. The hydraulic system reservoir

Why: Potable water is stored in tanks and piped to the lavatories and galleys for hand washing, drinking, and food service. FAA-H-8083-31B ch.16.

Which of the following is 'acceptable' data rather than 'approved' data?

1. AC 43.13-1B methods, techniques, and practices ✓
2. A Supplemental Type Certificate (STC)
3. A Type Certificate Data Sheet (TCDS)

Why: AC 43.13-1B provides acceptable (not approved) methods usable when no approved data exists; STCs and TCDS are examples of approved data. FAA-H-8083-31B ch.2.

Why are heater blankets, inline heaters, and thermostats fitted to potable water and waste lines and drain masts?

1. To prevent the water/waste from freezing and bursting or blocking the lines at low temperature ✓
2. To warm the water for passenger comfort during cruise according to the manufacturer's service data
3. To speed the flow of waste by reducing its viscosity

Why: Heater blankets/boots, inline heaters, and thermostatically controlled drain-mast heaters keep the water supply lines, waste drain lines, and drain masts above freezing so they do not freeze, burst, or block in flight. FAA-H-8083-31B ch.15.

A thermocouple fire detection system triggers a warning based on what?

1. The rate of temperature rise — it does not warn on a slow, general overheat ✓
2. A fixed absolute temperature, giving a warning on any slow overheat
3. The presence of smoke particles in the airflow

Why: The thermocouple system operates on the rate of temperature rise (a rapid rise creates a voltage between hot and cold junctions); it does NOT give a warning when the engine slowly overheats. FAA-H-8083-31B ch.17.

'Supercooled' water droplets, which cause structural icing, are droplets that are what?

1. Still liquid even though their temperature is below freezing, freezing on impact with the airframe ✓
2. Frozen solid before they strike the aircraft per the applicable maintenance manual according to the manufacturer's service data
3. Warmer than the surrounding air

Why: Supercooled droplets remain liquid at temperatures below 0 degrees C; when they strike the airframe they freeze on impact, forming structural ice. FAA-H-8083-31B ch.15.

What is the minimum edge distance for a universal head rivet versus a countersunk rivet?

1. 2 times the diameter for universal, 2.5 times the diameter for countersunk ✓
2. 1.5 times the diameter for universal, 2 times the diameter for countersunk
3. 3 times the diameter for universal, 3.5 times the diameter for countersunk

Why: The minimum edge distance is 2 times the rivet diameter for universal head rivets and 2.5 times the diameter for countersunk rivets. FAA-H-8083-31B ch.4.

Gyroscopic precession affects a rotor such that a control force applied at one point takes effect where?

1. Approximately 90 degrees later in the direction of rotation ✓
2. At the exact point where the force is applied
3. 180 degrees opposite the point of application

Why: Because the spinning rotor acts like a gyroscope, a force applied to change the disk takes effect approximately 90 degrees later in the direction of rotation (gyroscopic precession); rotor controls are rigged to account for this. FAA-H-8083-31B ch.2.

How should transparent acrylic windows be cleaned to avoid damage?

1. With mild soap and plenty of water, never with harsh solvents that soften or craze acrylic ✓
2. With acetone or lacquer thinner applied on a cloth, to quickly dissolve any surface films and grime
3. By dry-wiping firmly with a coarse dry cloth to lift embedded grit particles from the surface

Why: Clean acrylic with mild soap and water; avoid harsh solvents (acetone, thinners) that soften the plastic and cause crazing, and avoid dry-wiping that scratches the soft surface. FAA-H-8083-31B ch.7.

Which class of fire involves energized electrical equipment, as could occur in an avionics bay?

1. Class C ✓
2. Class A
3. Class D

Why: Class C fires involve energized electrical wiring and equipment (Class A = ordinary combustibles, B = flammable liquids, D = metals); appropriate agents and detection are provided for the fire zones/areas at risk. FAA-H-8083-31B ch.17.

For a helicopter to hover in a no-wind condition, what force relationship must exist?

1. The sum of lift and thrust equals the sum of weight and drag ✓
2. Lift alone must exceed weight, with thrust and drag ignored
3. Thrust must exceed lift for the aircraft to remain stationary

Why: In a hover (no wind), the tip-path plane is horizontal and the sum of the lift and thrust forces must equal the sum of the weight and drag forces; more lift/thrust climbs, less descends. FAA-H-8083-31B ch.2.

When a rivet must pass completely through a tubular member, the rivet diameter should be at least what fraction of the tube's outside diameter?

1. 1/8 of the outside diameter of the tube ✓
2. 1/4 of the outside diameter of the tube
3. 1/2 of the outside diameter of the tube

Why: When rivets pass completely through tubular members, select a rivet diameter at least 1/8 of the outside diameter of the tube (use the next larger size). FAA-H-8083-31B ch.4.

Anti-skid braking systems are generally armed by

1. the application of brakes.
2. a switch in the cockpit.
3. the rotation of the wheels above a certain speed. ✓

Why: Anti-skid systems are generally armed by the rotation of the wheels above a certain speed. FAA-H-8083-31B ch.13.

Any wooden member that has been overstressed is subject to which type of failure?

1. Stretch.
2. Compression. ✓
3. Torsion.

Why: An overstressed wooden member is subject to a compression failure (a buckling fracture across the grain). FAA-H-8083-31B ch.6.

Which component stores hydraulic fluid and provides a supply/return point for the system?

1. The reservoir ✓
2. The accumulator
3. The selector valve

Why: The reservoir stores the system's hydraulic fluid, provides a place for expansion and de-aeration, and supplies the pump; core components also include the pump, accumulator, relief valve, selector valves, and actuators. FAA-H-8083-31B ch.12.

A DME antenna should be installed on the aircraft in a position that will

1. not be blanked out by the wing when the aircraft is banked. ✓
2. not be blanked out by the vertical stabilizer.
3. facilitate cleaning, inspection, and maintenance.

Why: A DME antenna is positioned so it is not blanked out by the wing when the aircraft is banked. FAA-H-8083-31B ch.11.