Hydraulic and Pneumatic Power Flashcards
7 cards from real Airframe Mechanic Certification 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 and Pneumatic Power flashcards as text
A shuttle valve in a hydraulic system is used to:
Answer: Automatically select the higher of two pressure sources to supply a critical component
A shuttle valve connects a component to whichever of two supply sources (normal or emergency) has the higher pressure, ensuring continuous supply.
What determines the maximum safe working pressure of a hydraulic hose assembly?
Answer: The manufacturer's published rated working pressure for that hose specification
Each hose assembly has a manufacturer-specified maximum working pressure that must equal or exceed the system's operating pressure.
Fluid in an aircraft hydraulic reservoir is maintained above the minimum level primarily to:
Answer: Prevent pump cavitation and allow for thermal expansion of fluid
Adequate fluid level prevents the pump from drawing air (cavitation) and provides volume for fluid that expands when heated during operation.
An aircraft pneumatic system using engine bleed air would MOST likely use bleed air from which compressor stage?
Answer: An intermediate or high-pressure compressor stage depending on engine power setting
Bleed air is tapped from intermediate or high-pressure compressor stages, with automatic selection between stages to maintain adequate pressure across the flight envelope.
What is the function of a priority valve in a hydraulic system?
Answer: To ensure that flight-critical systems receive pressure before non-essential systems when pressure is low
A priority valve closes off non-critical hydraulic consumers when system pressure drops, reserving available pressure for flight-critical systems like flight controls.
When installing a hydraulic fitting using the B-nut (flareless) tube fitting method, the sleeve is set by:
Answer: Pre-setting the sleeve onto the tube by tightening until resistance is felt, then backing off before final installation
Flareless fittings require pre-setting the sleeve onto the tube in a presetting tool or union before final assembly to properly bite and grip the tube.
If a hydraulic system pressure gauge reads zero with the pump operating, the FIRST item to check is:
Answer: Whether the system selector valve is open and the pump is actually receiving fluid
Zero pressure with the pump running often indicates no fluid is reaching the pump (closed isolation valve, low reservoir) or the pump is not actually running, making fluid supply and pump operation the first checks.