A&P A&P - Aircraft and Powerplant Hydraulic and Pneumatic Systems

Question 1

What type of fluid is used in most modern commercial aircraft hydraulic systems?

Accepted Answer

Skydrol (phosphate ester-based)

Answer

MIL-H-5606 (mineral oil-based)

Answer

MIL-H-83282 (synthetic hydrocarbon)

Answer

Castor oil-based fluid

Question 2

What is the primary function of a hydraulic accumulator in an aircraft system?

Accepted Answer

Store pressurized fluid to dampen pressure surges and provide emergency power

Answer

Filter contaminants from the hydraulic fluid

Answer

Convert hydraulic pressure into electrical energy

Answer

Regulate fluid temperature throughout the system

Question 3

Which component in a hydraulic system prevents pressure from exceeding a safe maximum?

Accepted Answer

Relief valve

Answer

Check valve

Answer

Selector valve

Answer

Priority valve

Question 4

A hydraulic system pressure gauge reads zero with the engine running. What is the MOST likely cause?

Accepted Answer

Failed engine-driven pump or broken drive shaft

Answer

Low fluid temperature

Answer

Accumulator overcharged with nitrogen

Answer

Selector valve stuck in neutral

Question 5

What is the purpose of a hydraulic system's case drain line on a variable-displacement pump?

Accepted Answer

Return leakage fluid from the pump housing back to the reservoir

Answer

Supply fluid to the pump inlet

Answer

Provide a path for emergency fluid bypass

Answer

Cool the hydraulic actuators

Question 6

In a pneumatic system, what component is used to remove moisture from compressed air before it enters system components?

Accepted Answer

Air/oil separator or moisture separator

Answer

Pressure regulator

Answer

Restrictor orifice

Answer

Pneumatic accumulator