A&P Hydraulic and Pneumatic Systems Questions and Answers

Question 1

A technician observes that a hydraulic system's pressure gauge fluctuates rapidly and the system operates erratically, especially upon initial actuator movement.
Which component is most likely failing to perform its function of dampening pressure surges?

Accepted Answer

Accumulator

Answer

Sequence valve

Answer

Pressure relief valve

Answer

Selector valve

Question 2

Which of the following is the primary purpose of a hydraulic sequence valve in a landing gear system?

Accepted Answer

To ensure the gear doors are open before the gear begins to extend.

Answer

To regulate system pressure to a predetermined maximum.

Answer

To allow fluid to flow in one direction only.

Answer

To store hydraulic fluid for emergency gear extension.

Question 3

A technician is servicing a large transport category aircraft hydraulic system that uses a purple-colored, phosphate-ester based fluid (Skydrol). What type of seal material MUST be used for components within this system?

Accepted Answer

Butyl rubber or Ethylene Propylene (EPDM)

Answer

Neoprene

Answer

Buna-N

Answer

Natural rubber

Question 4

In a high-pressure pneumatic system, what is the primary function of a moisture separator?

Accepted Answer

To remove entrained water vapor to prevent freezing and corrosion.

Answer

To add oil to the air for lubricating pneumatic components.

Answer

To regulate the downstream air pressure to a constant value.

Answer

To store a reserve of compressed air for emergency operations.

Question 5

An aircraft hydraulic system is powered by a constant-displacement pump. To prevent pump and system overload when no services are being operated, what component diverts the full output of the pump back to the reservoir at low pressure?

Accepted Answer

Unloading valve

Answer

System pressure relief valve

Answer

Shuttle valve

Answer

Check valve

Question 6

What is the mandatory, first procedural step before checking the nitrogen pre-charge pressure of a hydraulic system accumulator?

Accepted Answer

Ensure all hydraulic system pressure is completely discharged.

Answer

Operate the system until normal operating temperature is reached.

Answer

Pressurize the hydraulic system to its maximum rated value.

Answer

Cycle a nearby hydraulic actuator several times.

A technician observes that a hydraulic system's pressure gauge fluctuates rapidly and the system operates erratically, especially upon initial actuator movement.Which component is most likely failing to perform its function of dampening pressure surges?

A technician observes that a hydraulic system's pressure gauge fluctuates rapidly and the system operates erratically, especially upon initial actuator movement.
Which component is most likely failing to perform its function of dampening pressure surges?