A&P Aircraft Hydraulic & Pneumatic Systems Flashcards
6 cards from real A&P practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 A&P Aircraft Hydraulic & Pneumatic Systems flashcards as text
In an aircraft pneumatic system, what is the most common source of high-pressure air used for system operation?
Answer: Bleed air tapped from the engine compressor stages
Most turbine-powered aircraft pneumatic systems use bleed air extracted from the engine's compressor section as the primary pressure source for flight controls, pressurization, and other pneumatic actuators.
What is the function of a pneumatic system's pressure regulator?
Answer: Reduce high-pressure bleed air to a lower, usable system pressure
The pressure regulator reduces the very high pressure of engine bleed air to a lower, controlled pressure suitable for operating pneumatic components without damage.
Why is moisture a critical concern in pneumatic systems, especially at high altitudes?
Answer: Moisture can freeze in lines and valves at altitude, causing blockages and system failure
Water vapor in pneumatic lines can freeze at the low temperatures encountered at altitude, blocking orifices, valves, and lines and causing system malfunctions.
A hydraulic actuator that holds position under load without continuous fluid flow is best described as a:
Answer: Locked (mechanically locked) actuator
Mechanically locked actuators (such as those used for landing gear) hold their position through a mechanical lock so they do not require continuous hydraulic pressure to remain extended or retracted.
What is the purpose of a debooster valve in an aircraft hydraulic brake system?
Answer: Reduce high system pressure to a lower, controllable pressure at the brake actuators
A debooster valve reduces the high hydraulic system pressure to a lower pressure suitable for the brake actuators, protecting brake components from overpressure.
Which type of hydraulic pump provides a constant flow regardless of system pressure, making it simple but potentially wasteful of energy?
Answer: Fixed-displacement (constant-delivery) pump
A fixed-displacement pump delivers a constant volume of fluid per revolution regardless of system demand; excess fluid is bypassed through the relief valve, generating heat in inefficient designs.