NIFE ENGINES Chapter 5 - Hydraulic
Systems Exam Questions and
Answers
Pressurized Reservoir - Answer-Pressurized by bleed air from the compressor or
hydraulic system pressure. Used in high performance aircraft.
Types of Pumps - Answer-Provide adequate flow of fluid.
1) Hand Pumps
2) Power Pumps
Hand Pumps - Answer-Supply fluid pressure to subsystems (ie landing gear). Normally
only emergency systems.
Power Pumps - Answer-Typically driven by engine, but may be electric-motor driven.
Displace a variable amount of fluid (regulates volume delivery based on system flow
demand) or a constant amount of fluid (delivers constant fluid output for any given
rotational speed). Constant displacement pumps need a pressure regulator/unloader
valve to divert any excess pump flow back to the reservoir therefore maintaining a
constant pressure.
Check Valve - Answer-Maintains one-way flow in system by allowing free flow of fluid
from pumps, but preventing back flow of fluid. Works with accumulator.
Accumulator - Answer-- **ACTS AS SHOCK ABSORBER**
- Supplements the pump's output by storing fluid under pressure
- Stores fluid under pressure for emergency operations
Filters - Answer-Ensure the delivery of contaminant free hydraulic fluid.
Relief valves - Answer-Safety valve that prevents excess pressure build up.
Pressure gauge - Answer-Indicate amount of pressure in the hydraulic system. If low,
most likely pump failure.
Pressure switches - Answer-Indicates a hydraulic pressure drop below allowable limits
Hydraulic fuses - Answer-Safety devices that detect/gauge leak-producing damage. If
sensed, they shut line down to prevent fluid loss. (Not resettable)
Systems Exam Questions and
Answers
Pressurized Reservoir - Answer-Pressurized by bleed air from the compressor or
hydraulic system pressure. Used in high performance aircraft.
Types of Pumps - Answer-Provide adequate flow of fluid.
1) Hand Pumps
2) Power Pumps
Hand Pumps - Answer-Supply fluid pressure to subsystems (ie landing gear). Normally
only emergency systems.
Power Pumps - Answer-Typically driven by engine, but may be electric-motor driven.
Displace a variable amount of fluid (regulates volume delivery based on system flow
demand) or a constant amount of fluid (delivers constant fluid output for any given
rotational speed). Constant displacement pumps need a pressure regulator/unloader
valve to divert any excess pump flow back to the reservoir therefore maintaining a
constant pressure.
Check Valve - Answer-Maintains one-way flow in system by allowing free flow of fluid
from pumps, but preventing back flow of fluid. Works with accumulator.
Accumulator - Answer-- **ACTS AS SHOCK ABSORBER**
- Supplements the pump's output by storing fluid under pressure
- Stores fluid under pressure for emergency operations
Filters - Answer-Ensure the delivery of contaminant free hydraulic fluid.
Relief valves - Answer-Safety valve that prevents excess pressure build up.
Pressure gauge - Answer-Indicate amount of pressure in the hydraulic system. If low,
most likely pump failure.
Pressure switches - Answer-Indicates a hydraulic pressure drop below allowable limits
Hydraulic fuses - Answer-Safety devices that detect/gauge leak-producing damage. If
sensed, they shut line down to prevent fluid loss. (Not resettable)
