Hydraulic & Pneumatic Systems Flashcards
7 cards from real ACS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Hydraulic & Pneumatic Systems flashcards as text
What is the purpose of a pneumatic system bootstrap reservoir?
Answer: Pressurize the reservoir above atmospheric pressure to prevent pump cavitation at altitude
A bootstrap reservoir is pressurized above the fluid inlet pressure so the hydraulic or pneumatic pump receives adequate inlet pressure, preventing cavitation at high altitudes.
Which component in a pneumatic system performs the same function as a hydraulic system relief valve?
Answer: Pressure relief valve
A pneumatic pressure relief valve protects the system from overpressure just as a hydraulic relief valve does, opening to vent excess pressure to atmosphere.
What is the main hazard of moisture contamination in a high-pressure pneumatic system?
Answer: Moisture can freeze at altitude, blocking orifices and valves
Water moisture in pneumatic lines can freeze at altitude temperatures, blocking critical orifices, valves, and lines, causing system failure.
When inspecting a hydraulic actuator for internal leakage, what is the most reliable method?
Answer: Measure the time it takes the actuator rod to drift under a known load with ports blocked
Applying a load and timing rod drift with ports blocked reveals internal seal bypass, which is the definitive test for internal actuator leakage.
What is the correct torque technique when installing AN/MS flareless tube fittings?
Answer: Use the 'finger-tight plus turns' method specified in the applicable maintenance manual
Flareless fitting installation requires presetting the ferrule on the tube first, then during final assembly using the turns method specified in the maintenance manual.
What is the purpose of a desiccant in an aircraft pneumatic system?
Answer: Remove moisture from compressed air before it enters system components
A desiccant absorbs moisture from compressed air, preventing ice formation at altitude and corrosion within system components.
What does a hydraulic system ground test unit (GTU) allow a technician to do?
Answer: Operate aircraft hydraulic systems using external ground power without running the engines
A ground test unit provides external hydraulic pressure and flow, allowing full system operation and testing without starting the aircraft engines.