Aircraft Systems Flashcards

A capacitance-type fuel quantity probe determines fuel quantity primarily by sensing what?

Answer: The difference in dielectric constant between fuel and air

Fuel has a higher dielectric constant than air, so probe capacitance rises as fuel level rises.

Which flight instrument requires both pitot (ram) pressure and static pressure to operate?

Answer: Airspeed indicator

The airspeed indicator measures the difference between pitot and static pressure (dynamic pressure).

A thermocouple-type fire detection system generates a warning based on what condition?

Answer: A rapid rate of temperature rise at the hot junctions

Thermocouple systems respond to the rate of temperature rise, comparing hot junctions to a reference junction.

What is the primary function of an anti-skid system's wheel speed transducers?

Answer: To signal the controller so it can reduce brake pressure before a wheel locks

Wheel speed signals let the anti-skid controller detect impending skids and relieve brake pressure.

Why is a weight-on-wheels (squat) switch incorporated into landing gear circuits?

Answer: To prevent gear retraction while the aircraft is on the ground

The squat switch opens the retraction circuit when strut compression indicates the aircraft is on the ground.

In a typical pressurized aircraft, cabin pressure is regulated mainly by controlling which component?

Answer: The outflow valve

The pressurization controller modulates the outflow valve to set how much air leaves the cabin.

A stall warning system on many transport aircraft receives its primary input from which sensor?

Answer: Angle-of-attack vane or lift transducer

Stall is a function of angle of attack, so AOA vanes or lift transducers feed the stall warning computer.