ACS Hydraulic & Pneumatic Systems 2

Question 1

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

Accepted Answer

Store hydraulic fluid under pressure to supplement the pump during peak demands

Answer

A hydraulic accumulator stores pressurized fluid to assist the pump during peak demand periods, such as when multiple systems operate simultaneously.

Question 2

Which type of hydraulic seal is most commonly used between two parts that have relative motion (dynamic application)?

Accepted Answer

O-ring or lip seal in a dynamic groove

Answer

Dynamic seals such as O-rings installed in dynamic grooves or lip seals are designed to prevent leakage between moving components.

Question 3

When bleeding an aircraft hydraulic system, why is it important to work from the component farthest from the reservoir first?

Accepted Answer

To purge all air systematically toward the reservoir and prevent air pockets

Answer

Bleeding from the farthest point ensures air bubbles are progressively pushed back toward the reservoir rather than trapped in the system.

Question 4

What does a hydraulic system pressure relief valve protect against?

Accepted Answer

Thermal expansion causing pressure spikes that exceed system design limits

Answer

The pressure relief valve opens to bypass fluid back to the reservoir when system pressure exceeds the maximum design limit, protecting components from overpressure damage.

Question 5

What material are most aircraft hydraulic lines made of when routing through areas subject to vibration?

Accepted Answer

Flexible rubber hose reinforced with braided wire

Answer

Flexible braided hose is used in areas subject to vibration or relative movement because it can absorb movement without cracking or failing.

(ACS) Airman Certification Standard Certified Mechanic Practice Test

(ACS) Airman Certification Standard Certified Mechanic Practice Test

ACS Hydraulic & Pneumatic Systems 2