A&P Hydraulic and Pneumatic Systems 1

Question 1

What is the primary purpose of a hydraulic system relief valve on an aircraft?

Accepted Answer

To limit maximum system pressure and prevent overpressure damage

Answer

To filter contaminants from the fluid

Answer

To regulate fluid temperature

Answer

To separate air from the hydraulic fluid

Question 2

Which type of hydraulic fluid is used in most modern transport-category aircraft and is compatible with natural rubber seals?

Accepted Answer

Skydrol (phosphate ester)

Answer

MIL-PRF-5606 (mineral-based)

Answer

MIL-PRF-83282 (synthetic hydrocarbon)

Answer

Ethylene glycol-based fluid

Question 3

What color is MIL-PRF-5606 mineral-based hydraulic fluid?

Accepted Answer

Red

Answer

Blue

Answer

Purple

Answer

Clear

Question 4

In an aircraft hydraulic system, what is the function of the accumulator?

Accepted Answer

Store pressurized fluid to supplement the pump during peak demands

Answer

Filter the hydraulic fluid before it reaches actuators

Answer

Sense system pressure and signal the pump to start

Answer

Cool hydraulic fluid returning from actuators

Question 5

What is the purpose of a hydraulic power pack (self-contained unit) on light aircraft?

Accepted Answer

It replaces the engine-driven pump with an electric motor-driven pump, reservoir, and valve assembly

Answer

It stores emergency hydraulic fluid in case of a main system leak

Answer

It converts hydraulic pressure to pneumatic pressure

Answer

It provides a backup source of electrical power

Question 6

When servicing an aircraft pneumatic system's air bottle, what must a technician verify before removing the filler valve?

Accepted Answer

That the bottle pressure has been bled to zero

Answer

That the aircraft is on jacks

Answer

That the engine is running to maintain pressure

Answer

That the hydraulic system is isolated