AMT Hydraulics and Pneumatics Questions and Answers

Question 1

An aircraft's hydraulic system utilizes a component to ensure the landing gear doors are fully open before the landing gear begins to extend. What is this component called?

Accepted Answer

A sequence valve

Answer

A sequence valve is designed to control the order of operations in a hydraulic circuit. In the context of landing gear, it ensures that one action (doors opening) is completed before the next action (gear extending) begins.

Question 2

Which of the following is a primary advantage of using a phosphate ester-based hydraulic fluid, such as Skydrol, over a mineral-based fluid in modern transport category aircraft?

Accepted Answer

Superior fire resistance

Answer

Phosphate ester-based hydraulic fluids like Skydrol are widely used in commercial aviation primarily because of their excellent fire-resistant properties, which enhance safety in high-temperature and high-pressure hydraulic systems.

Question 3

A technician is servicing a hydraulic accumulator that is part of an aircraft's main hydraulic system. What is one of the primary functions of this component?

Accepted Answer

To store hydraulic fluid under pressure to supplement the pump during peak demand

Answer

Hydraulic accumulators store incompressible fluid under pressure from an external source, typically compressed nitrogen. This stored energy is used to supplement the hydraulic pump during periods of high demand, dampen pressure surges, and provide emergency pressure if the pump fails.

Question 4

The fundamental principle that allows hydraulic systems to transmit and multiply force is known as:

Accepted Answer

Pascal's Law

Answer

Pascal's Law states that a pressure change at any point in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere. This principle allows a small force applied to a small area to generate a much larger force on a larger area.

Question 5

Compared to hydraulic systems, a primary characteristic of aircraft pneumatic systems is that they generally:

Accepted Answer

Use a compressible fluid (air or nitrogen)

Answer

Pneumatic systems use a compressible gas, such as air or nitrogen, as the working fluid. This is a key difference from hydraulic systems, which use incompressible liquids. The compressibility of air results in less precise motion control compared to hydraulics.

(AMT) Aviation Maintenance Technician Practice Test

(AMT) Aviation Maintenance Technician Practice Test

AMT Hydraulics and Pneumatics Questions and Answers