AME - Aircraft Maintenance Engineer Hydraulic and Pneumatic Systems Questions and Answers

Question 1

An AME is troubleshooting an aircraft hydraulic system and observes that the system pressure fluctuates rapidly and excessively when a component is operated. The pump is known to be in good condition. What is the most likely cause of this issue?

Accepted Answer

The accumulator has lost its nitrogen pre-charge.

Answer

The primary function of an accumulator is to dampen pressure surges and supplement pump flow. If the nitrogen pre-charge is lost, the accumulator's diaphragm or piston has no gaseous 'cushion' to absorb pressure spikes from pump operation and component actuation, leading to rapid and excessive pressure fluctuations.

Question 2

Which of the following is a critical safety and maintenance consideration when working with phosphate ester-based hydraulic fluids such as Skydrol?

Accepted Answer

It is an excellent paint remover and is harmful to many traditional aircraft finishes and plastics.

Answer

Phosphate ester-based hydraulic fluids like Skydrol are known for their excellent fire resistance but are also powerful solvents. They are incompatible with many materials, including most standard paints, plastics, and natural rubber seals, which they can soften and destroy. Proper PPE, including gloves and goggles, is required as the fluid is irritating to human tissue.

Question 3

What is the primary operational characteristic of a constant-delivery hydraulic pump, such as a gear-type pump?

Accepted Answer

It delivers a fixed volume of fluid per revolution, regardless of system pressure.

Answer

A constant-delivery (or constant-displacement) pump moves a fixed amount of fluid for each rotation of the pump's shaft. Because it is always attempting to move this fluid, the system must incorporate a pressure regulator or relief valve to divert excess flow and prevent over-pressurization when there is low demand.

Question 4

An AME is tasked with replacing a component in the aircraft's high-pressure pneumatic system. Before loosening any fittings on the component, what is the most critical safety step that must be performed?

Accepted Answer

Confirm that the specific pneumatic system has been fully depressurized by checking the pressure gauge.

Answer

High-pressure pneumatic systems store a tremendous amount of energy. Attempting to disconnect a fitting before fully bleeding off the pressure can result in an explosive release of gas, turning components into dangerous projectiles. Verifying a zero-pressure reading on the system gauge is the most critical safety action to prevent serious injury.

Question 5

In a typical large transport aircraft, which component is primarily responsible for regulating the pressure and temperature of engine bleed air before it is distributed to various pneumatic systems?

Accepted Answer

The Pressure Regulating and Shutoff Valve (PRSOV).

Answer

The Pressure Regulating and Shutoff Valve (PRSOV), often called a Bleed Air Valve, is the primary component that modulates the flow of hot, high-pressure air from the engine's compressor section. It regulates the downstream pressure and often incorporates a heat exchanger or precooler to reduce the air to a usable temperature for systems like air conditioning and wing anti-ice.

AME - Aircraft Maintenance Engineer Practice Test

AME - Aircraft Maintenance Engineer Practice Test

AME - Aircraft Maintenance Engineer Hydraulic and Pneumatic Systems Questions and Answers