Free FAA AMA Exam Flashcards

Measured from the hole center to the edge of the sheet: 2 rivet diameters minimum for protruding (universal) head rivets and 2.5 diameters for countersunk rivets, and never more than 4 diameters. Too small an edge margin lets the sheet crack and tear out to the edge under load.

Rivet pitch (center to center within a row) is never less than 3 rivet diameters, and typically runs 4 to 6 diameters. Rows are spaced no closer than 2.5 diameters. Pitch is tightened toward the minimum on parts carrying bending loads so the skin cannot buckle between rivets.

Bending compresses the inside of the bend and stretches the outside, while one line is unaffected: the neutral axis, about 0.445 times material thickness from the inside of the bend radius. Bend allowance is the length of material consumed along that neutral axis and must be added into the flat layout.

Use a neutral flame. An excess-acetylene (carburizing) flame drives carbon into the joint and leaves a hard, brittle weld; an oxidizing flame burns the metal and leaves a weak, porous weld. Welded steel tube repairs must still follow FAA-approved data for the repair method.

Covering stays airworthy until its breaking strength falls below 70 percent of the strength of new fabric required for that aircraft. Example: an aircraft certificated with Grade-A cotton, 80 pounds new, becomes unairworthy when the fabric tests below 56 pounds.

Ultraviolet radiation, not dirt or water, is what destroys fabric and the structure underneath it. Aluminum solids added to the butyrate coats reflect UV, so an unbroken UV-blocking film must be maintained over every exposed fabric surface.

No wood used in aircraft construction or repair may have a grain slope steeper than 1:15, whatever the species. Spruce is the reference species that substitutes are compared against, and certificated aircraft require wood traceable to a certified source.

Tapping a thin laminate or honeycomb panel and listening for a change from a sharp ring to a dull thud reveals delamination or disbond. It works only on thin skins; thicker or multi-layer structure requires ultrasonic, bond tester, or radiographic inspection.

Tension is read with a tensiometer using the riser matched to the cable size, then compared against the aircraft rigging chart for the ambient temperature, because cable and structure change length at different rates. Skipping the temperature correction leaves the system slack in cold weather or overtight in heat.

No more than three threads may be exposed outside the barrel at either end, and both terminals must be screwed in an equal number of turns. After adjustment the turnbuckle must be safetied; the double-wrap safety wire method is preferred.

Any repair that adds or removes weight fore or aft of the hinge centerline requires rebalancing, and balance must be re-checked any time the aircraft is repainted. An out-of-balance surface will not stay streamlined in flight and invites flutter.

An annual is required every 12 calendar months on almost every aircraft and must be approved by a mechanic holding an Inspection Authorization. A 100-hour inspection applies only when the aircraft carries persons for hire or is used for flight instruction for hire, and an A&P may sign it. Both use the scope of Part 43 Appendix D.

The 100 hours may be exceeded by not more than 10 hours, and only while en route to a place where the inspection can be done. Those excess hours are then subtracted from the next 100-hour interval (14 CFR 91.409(b)).

If the aircraft is not approved for return to service, 14 CFR 43.11 requires the record entry to certify the inspection type and state that a dated list of discrepancies and unairworthy items was provided to the owner or operator. The owner, not the mechanic, decides how those items get corrected.

For a major repair or major alteration, Part 43 Appendix B requires FAA Form 337 executed at least in duplicate, a signed copy given to the aircraft owner, and a copy forwarded to the FAA Aircraft Registration Branch in Oklahoma City within 48 hours after return to service.

Fluid is forced from the lower chamber through an orifice, usually regulated by a tapered metering pin, and that restricted flow absorbs the impact energy. The compressed air or nitrogen above the fluid acts as a spring and carries static weight, so a strut sitting low normally needs gas, not fluid.

Torque links (scissors) mechanically tie the piston to the cylinder so the wheel stays aligned and the strut cannot rotate or over-extend. A shimmy damper is a separate hydraulic unit whose only job is damping the rapid nosewheel oscillation called shimmy.

Touchdown protection prevents brake application before the wheels spin up, which would blow tires on contact. Using wheel speed sensors and the air/ground (squat) switch, it holds the brake lines open to return until the aircraft has weight on wheels and the wheels are turning.

Mineral based (MIL-H-5606, dyed red), polyalphaolefin (MIL-H-83282, fire resistant), and phosphate ester (Skydrol type). They are not interchangeable: contaminating MIL-H-83282 with MIL-H-5606 can destroy its fire resistance, and each category demands its own seal material.

A diaphragm, bladder, or piston separates a nitrogen or air preload from system fluid. The compressed gas dampens pressure surges, supplies flow beyond pump output during peak demand, and gives limited emergency operation. A lost preload shows up as rapid pressure fluctuation and constant pump cycling.

A sequence valve enforces order of operation, holding pressure back until a set pressure or a mechanical trigger is reached, so gear doors finish opening before the gear moves. A shuttle valve automatically transfers an actuator from the normal system to an emergency source and isolates the failed side.

Hot bleed air passes through a heat exchanger, is compressed, cooled again, then expanded through an expansion turbine. Extracting work from the air drops its temperature sharply, and a water separator downstream removes the moisture that condenses out.

The outflow valve schedules normal cabin pressure. The positive pressure relief (safety) valve caps the maximum cabin-to-ambient differential. The negative pressure relief valve is spring loaded to open inward so ambient pressure can never exceed cabin pressure, a direction the pressure vessel was not designed to carry.

Oxygen components, fittings, and tools must be kept free of oil, grease, and petroleum-based cleaners, because those substances can ignite in high-pressure oxygen. Chemical (solid) oxygen generators add a second hazard: once fired they produce oxygen exothermically and become extremely hot.

The airspeed indicator is the only instrument fed by both the pitot (ram) line and the static line; the altimeter and vertical speed indicator use static pressure only. A static system defect therefore corrupts three instruments, while a pitot defect affects airspeed alone.

If the ram opening blocks while the drain hole stays open, trapped pressure bleeds out and airspeed falls toward zero. If the ram opening and the drain are both blocked, the trapped pressure makes the airspeed indicator act like an altimeter, reading higher as the aircraft climbs.

Rigidity in space keeps the spinning rotor's plane fixed, which is what makes attitude and heading indicators work. Precession is the reaction to an applied force, and it appears about 90 degrees later in the direction of rotation, which is why bearing friction or an off-axis force tilts a gyro unexpectedly.

For IFR flight, the static system, each altimeter, and the automatic pressure altitude reporting system must have been tested within the preceding 24 calendar months to Part 43 Appendices E and F (14 CFR 91.411). Each ATC transponder needs the same 24-calendar-month test to Appendix F (14 CFR 91.413).

Batteries must be replaced or recharged when the transmitter has been in use for more than 1 cumulative hour, or when 50 percent of their useful life has expired. The new expiration date must be marked on the outside of the transmitter and entered in the aircraft maintenance record (14 CFR 91.207(c)).

Within each 12 calendar months the ELT must be inspected for proper installation, battery corrosion, operation of the controls and crash sensor, and the presence of a sufficient signal radiated from its antenna (14 CFR 91.207(d)).

The encoder reports pressure altitude referenced to 29.92 in Hg, not the altitude shown on the pilot's set altimeter. ATC applies the local altimeter setting to display the aircraft's altitude, which is why encoder-to-altimeter correspondence is retested after maintenance that could introduce data error.

Static wicks bleed precipitation static off trailing edges so it cannot discharge across the airframe and blank out radio reception. Bonding straps give every component a low-resistance path to structure; a high-resistance bond shows up as radio noise and as a static hazard during refueling.

Vents hold tank pressure near ambient as fuel burns off and altitude changes. A blocked vent starves the engine as suction builds and can collapse or rupture the tank; vent systems use float and check valves so the tank stays vented without spilling fuel in any attitude.

Tank probes act as capacitors whose dielectric changes as fuel replaces air between the plates, and a bridge circuit compares them against a reference capacitor. The indication is calibrated in pounds, so it reports fuel by weight, unlike a float gauge that only measures volume.

Gravity systems depend on tanks mounted high enough above the engine to feed on head pressure alone, which limits them to high-wing light aircraft. Pressure-feed systems use boost pumps to keep positive pressure at the engine, prevent vapor lock at altitude, and make crossfeed and tank-to-tank transfer possible.

Circuit protection is sized to protect the wire, not the component on the end of it, so an oversized breaker can let a wire overheat inside a bundle. Breakers must also be trip-free, meaning they cannot be held closed against a fault.

A transformer rectifier (TR) unit steps AC down and rectifies it to DC to feed DC buses and the battery. An inverter runs the opposite direction, converting DC into AC so essential AC loads keep working when generator power is lost.

Size the wire for current-carrying capacity and for the allowable voltage drop over the full length of the run, then derate for bundling, altitude, and continuous versus intermittent duty. A long run frequently needs a heavier gauge than the current alone would suggest.

Anti-ice systems (bleed air leading edges, heated pitot and static ports, heated windshields) are turned on before ice forms and prevent accumulation. De-ice systems, typically pneumatic boots, are used after ice has accumulated and break it off the surface.

Heating elements keep ice from blocking the ram opening, drain hole, and static ports, which would otherwise produce false airspeed and altitude indications. The elements get hot enough to burn skin, so ground checks are brief and heat is not left on without airflow.

Rain is cleared by wipers, chemical rain repellent, hydrophobic coatings, or a pneumatic air blast. Windshield icing and fogging are handled separately by embedded electrical heating film run through a temperature controller with normal and high heat relays.

Both are an Inconel tube around a heat-sensitive core whose electrical resistance drops as temperature rises: Fenwal packs eutectic salt around a nickel center conductor, Kidde uses two wires in a thermistor core. The control unit senses the resistance drop and, because nothing is consumed, the loop resets when temperature falls.

A thermal switch (spot) detector closes its circuit at a fixed temperature, so it catches a general overheat anywhere it is mounted. A thermocouple detector responds to a rapid rate of temperature rise instead, so it catches a fast-developing fire but ignores a slow overheat.

A missing red disc means the container dumped its agent overboard through the thermal relief because of excessive heat. A missing yellow disc means the flight crew discharged the system normally. Either indication means the container must be replaced before the next flight.

Tracking determines whether every blade tip passes through the same tip path plane while the head is turning, checked with a flag and pole or an electronic strobe tracker. Tracking corrects tip path; dynamic balancing corrects mass distribution, and the two jobs are not interchangeable.

Low frequency (1 per rev or 2 per rev) traces to the main rotor itself. Medium frequency (roughly 4 to 6 per rev) usually means the airframe has lost its ability to absorb rotor vibration or a component such as a skid is loose. High frequency at tail rotor speed or faster points to the tail rotor, drive shaft, or another fast-turning part.

The vertical (drag or lead-lag) hinge lets blades hunt fore and aft in response to the Coriolis effect as rotor speed changes, the horizontal flapping hinge lets blades rise and fall to relieve dissymmetry of lift, and the feathering hinge allows pitch change about the spanwise axis.

Heater blankets, inline heaters, and heater boots protect potable water supply lines, tank drain hoses, waste drain lines, waste tank rinse fittings, and drain masts. Thermostats feed line temperature to a controller that switches the heaters on below freezing and off once the line is safe.

Gray water from galley and lavatory sinks goes to waste water tanks or overboard through heated drain masts. Toilet waste goes to a separate sealed waste tank drained and rinsed only at the service panel, so the two systems keep separate lines, drains, and servicing procedures.

Airplanes with a passenger capacity of 20 or more must have a lavatory smoke detector in the ceiling that warns the flight deck or the flight attendant stations, and each lavatory must have a built-in extinguisher that discharges automatically into the waste receptacle.