NCATT AET flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Four forces of flight
- Lift, weight, thrust, and drag act on an aircraft in flight; in steady, unaccelerated level flight, lift equals weight and thrust equals drag.
- Aircraft control axes
- Roll is motion about the longitudinal axis controlled by ailerons; pitch is about the lateral axis controlled by the elevator; yaw is about the vertical axis controlled by the rudder.
- Standard sea-level pressure
- In the ICAO standard atmosphere, sea-level pressure is 29.92 inches of mercury, or 1013.25 hectopascals, and is used as the altimeter setting reference.
- Critical angle of attack
- The angle of attack at which airflow separates from the wing and lift decreases abruptly; a stall occurs at this angle regardless of airspeed or attitude.
- Pascal's law
- Pressure applied to a confined fluid is transmitted undiminished in all directions, so hydraulic force equals pressure multiplied by piston area.
- Ohm's law
- Voltage equals current multiplied by resistance, written V = IR; it relates voltage, current, and resistance in a linear DC circuit.
- Series circuit
- A circuit with one current path: current is the same through all components, voltage divides among them, and total resistance is the sum of individual resistances.
- Parallel circuit
- A circuit with multiple current paths: voltage is the same across each branch, current divides among branches, and total resistance is less than the smallest branch resistance.
- RMS value of sine wave
- The root-mean-square value of a sine wave equals peak value divided by the square root of two, about 0.707 times peak, and produces equivalent heating.
- Capacitor behavior
- A capacitor stores energy in an electric field, blocks direct current when charged, and passes alternating current with reactance inversely proportional to frequency and capacitance.
- Transformer turns ratio
- Primary-to-secondary voltage ratio equals primary-to-secondary turns ratio; an ideal transformer conserves power, so current changes inversely with voltage.
- Binary number system
- Base-2 numbering using only 0 and 1; each bit position represents a power of two, and eight bits form one byte.
- AND gate
- A logic gate whose output is 1 only when all inputs are 1; if any input is 0, the output is 0.
- Analog-to-digital converter
- An ADC samples an analog voltage and quantizes it into discrete binary codes; resolution equals reference voltage divided by two raised to the bit count.
- ARINC 429 data bus
- A serial avionics data bus using 32-bit words over twisted-pair wiring, commonly at 12.5 or 100 kilobits per second, with one transmitter per bus.
- Built-in test equipment
- BITE is circuitry and software inside a line-replaceable unit that monitors operation, detects faults, and reports status to maintenance or cockpit systems.
- American Wire Gauge
- AWG numbers specify conductor size; a larger AWG number means a smaller conductor diameter and higher resistance per unit length.
- Crimp termination
- A solderless connection made by deforming a metal barrel around a conductor with a calibrated tool; it requires correct wire gauge, insertion depth, and pull test.
- Cable shield grounding
- A cable shield is typically grounded at one end to provide electrostatic shielding while avoiding ground loops that can induce noise currents.
- Coaxial cable
- A cable with a center conductor, dielectric, metallic shield, and jacket; impedance is typically 50 or 75 ohms and bends must respect minimum radius.
- Environmental splice
- A sealed wire splice using a crimp barrel and heat-shrink sleeve with adhesive that excludes moisture and provides strain relief.
- Connector keying
- Mechanical features on mating connectors that prevent incorrect engagement; keyways and clocking ensure pins mate only with their intended sockets.
- Measuring current with multimeter
- The meter is connected in series with the circuit so current flows through it; the circuit must be opened and the correct current range selected.
- Oscilloscope probe compensation
- Adjusting a probe's trimmer capacitor to match the oscilloscope input so a square wave displays flat tops, ensuring accurate amplitude and pulse response.
- Megohmmeter
- An instrument that applies a high DC test voltage to measure insulation resistance; the circuit must be de-energized and isolated before testing.
- Time-domain reflectometer
- A TDR sends pulses into a cable and measures reflections to locate opens, shorts, and impedance changes, displaying distance based on propagation velocity.
- Voltage drop test
- Measuring voltage across a connection or conductor while current flows; excessive drop indicates high resistance such as a corroded or loose termination.
- Line replaceable unit
- An avionics component designed to be removed and replaced as a unit on the aircraft, with standardized mounting, connectors, and built-in test capability.
- Voltage standing wave ratio
- VSWR measures impedance match in an antenna system; a value near 1:1 is ideal, while higher values indicate reflected power and reduced efficiency.
- Aircraft bonding
- Low-resistance electrical connection between aircraft structures and components that provides a return path and controls static discharge and lightning current.
- 400 Hz aircraft power
- Many aircraft use 115-volt alternating current at 400 hertz instead of 60 hertz, allowing smaller transformers and motors for the same power.
- Antenna ground plane
- A conductive surface beneath an antenna that provides the reference for radiation; its size and bonding affect radiation pattern and impedance.