3O Airplane Systems - Avionics

Question 0

1. What function does the avionics power switch have?

Answer 0

The avionics power switch controls power from the primary bus to the avionics bus. The circuit is protected by a combination power switch/circuit breaker. Aircraft avionics are isolated from electrical power when the switch is in the “Off” position. Also, if an overload should occur in the system, the avionics power switch will move to the “Off” position, causing an interruption of power to all aircraft avionics.

Question 1

2. What are static dischargers? (FAA-H-8083-31)

Answer 1

Static dischargers are installed on aircraft to reduce radio receiver interference caused by corona discharge, which is emitted from the aircraft as a result of precipitation static. Static dischargers, normally mounted on the trailing edges of the control surfaces, wing tips, and vertical stabilizer, discharge the precipitation static at points a critical length away from the wing and tail extremities where there is little or no coupling of the static into the radio antenna.

Question 2

3. Within what frequency band does the following type of navigational and communication equipment installed on board most aircraft operate? (AIM)

Answer 2

VOR receiver (VHF band)—108.0 to 117.95 MHz
Communication transceivers (VHF band)—118.0 to 136.975 MHz
DME receiver (UHF band)—960 MHz to 1215 MHz
ADF receiver (LF to MF band)—190 to 530 kHz
Note: Know the location and function of the various antennas on your aircraft!

Question 3

4. Describe the function of the following avionics equipment acronyms: AHRS, ADC, PFD, MFD, FD, FMS, TAWS. (FAA-H-8083-6)

Answer 3

AHRS—attitude and heading reference system. Composed of three-axis sensors that provide heading, attitude, and yaw information for aircraft. AHRS are designed to replace traditional mechanical gyroscopic flight instruments and provide superior reliability and accuracy.
ADC—air data computer. An aircraft computer that receives and processes pitot pressure, static pressure, and temperature to calculate very precise altitude, indicated airspeed, true airspeed, vertical speed, and air temperature.
PFD—primary flight display. A display that provides increased situational awareness to the pilot by replacing the traditional six instruments with an easy-to-scan display that shows the horizon, airspeed, altitude, vertical speed, trend, trim, rate-of-turn, and more.
MFD—multi-function display. A cockpit display capable of presenting information (navigation data, moving maps, terrain awareness, etc.) to the pilot in configurable ways; often used in concert with the PFD.
FD—flight director. An electronic flight computer that analyzes the navigation selections, signals, and aircraft parameters. It presents steering instructions on the flight display as command bars or crossbars for the pilot to position the nose of the aircraft over or follow.
FMS—flight management system. A computer system containing a database for programming of routes, approaches, and departures that can supply navigation data to the flight director/autopilot from various sources, and can calculate flight data such as fuel consumption, time remaining, possible range, and other values.
TAWS—terrain awareness and warning system. Uses the aircraft’s GPS navigation signal and altimetry systems to compare the position and trajectory of the aircraft against a more detailed terrain and obstacle database. This database attempts to detail every obstruction that could pose a threat to an aircraft in flight.

Question 4

• DUPLICATE*

5. What is the function of a magnetometer? (FAA-H-8083-6)

Answer 4

A magnetometer is a device that measures the strength of the earth’s magnetic field to determine aircraft heading; it provides this information digitally to the AHRS, which then sends it to the PFD.

Question 5

• DUPLICATE*
  6. If a failure of one of the displays (PFD or MFD) occurs in an aircraft with an electronic flight display, what will happen to the remaining operative display? (FAA-H-8083-6)

Answer 5

In the event of a display failure, some systems offer a “reversion” capability to display the primary flight instruments and engine instruments on the remaining operative display.