FAA Aviation Mechanic - Airframe (AMA) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Primary structure

Structure whose failure would endanger aircraft safety, such as wings, fuselage, and empennage; it requires the strongest inspection and repair standards.

Secondary structure

Structure that can fail without immediate danger to flight, such as fairings, wheel wells, or noncritical access panels.

Limit load

Maximum load expected in normal service; the aircraft must withstand it without permanent deformation or structural damage.

Ultimate load

Limit load multiplied by the factor of safety, typically 1.5; the structure must withstand it for three seconds without failure.

Stress formula

Stress equals applied load divided by cross-sectional area; tension, compression, shear, and torsion describe how the load acts.

Strain definition

Strain is deformation per unit original length; it measures how much a structure stretches, compresses, or twists under stress.

Bend allowance

For sheet metal, bend allowance equals the neutral-axis arc length and is calculated from bend angle, radius, thickness, and K-factor.

Rivet edge distance

Minimum rivet edge distance is usually two rivet diameters from the center of the rivet to the edge of the sheet.

Delamination

Separation of composite layers; detect it by tap testing, ultrasonic inspection, or visual signs such as surface swelling and cracking.

Galvanic corrosion

Corrosion caused by electrical contact between dissimilar metals in the presence of an electrolyte; isolate the joint and use compatible hardware.

Buckling

Failure mode of a compression member that bows sideways before crushing; longer, slender members buckle at lower loads.

Pascal's law

Pressure applied to a confined fluid is transmitted equally in all directions; hydraulic force equals pressure times piston area.

Hydraulic fluid color

MIL-PRF-5606 and 83282 fluids are red mineral-based; Skydrol phosphate-ester fluid is purple and requires compatible seals.

Ohm's law

In a DC circuit, voltage equals current times resistance (E = I × R), and current equals voltage divided by resistance.

Electrical power

Power in a DC circuit equals voltage times current (P = E × I); one watt equals one volt times one ampere.

Pitot-static airspeed

Airspeed indicator uses pitot impact pressure and static pressure; the difference between them drives the airspeed indication.

Altimeter source

The altimeter uses static pressure only and displays altitude corresponding to the outside atmospheric pressure.

Outflow valve

Cabin pressurization is controlled by the outflow valve, which regulates the rate at which air leaves the pressurized fuselage.

Landing gear shimmy

Shimmy is rapid oscillation of a nose or main wheel; a shimmy damper or steering damper absorbs the oscillation.

Deice boots

Pneumatic deice boots inflate with air to break ice from leading edges; they remove ice after it has formed.

Fuel sump drain

Low-point drain used to remove water and sediment from fuel tanks during preflight and maintenance inspection.

Brake bleeding

Brake hydraulic systems are bled to remove air; trapped air causes a spongy pedal and reduces braking effectiveness.

Annual inspection

Required every 12 calendar months for most aircraft; a certificated mechanic with airframe rating may perform and return it to service.

100-hour inspection

Required for aircraft operated for hire or used in flight instruction; it must be performed within 100 hours of flight time.

AD compliance

Airworthiness Directives are mandatory; compliance must be recorded, and the aircraft cannot be returned to service until applicable ADs are met.

Form 337

Used to record major repairs or alterations and obtain approval; a copy is carried on the aircraft.

Dye penetrant

Surface nondestructive test for cracks in nonporous materials; penetrant enters defects and is drawn out by a developer.

Magnetic particle

Nondestructive test for surface and near-surface cracks in ferrous metals; magnetic particles gather at flux leakage.

Eddy current

Nondestructive test using electromagnetic induction to detect cracks and corrosion in conductive materials, especially aluminum.

Ultrasonic inspection

Nondestructive test using high-frequency sound waves to find internal flaws, delamination, and thickness changes in metal and composite structures.

Boroscope inspection

Visual inspection inside engines or structures using a flexible or rigid optical scope through small access ports.

Corrosion inspection

Look for blistered paint, discoloration, rivet staining, and powdery deposits; clean and treat corrosion before it spreads.