FAA Powerplant Written Practice Test

What role does a dump valve play in a gas turbine engine's fuel system?

1. Increases fuel pressure for ignition

2. Drains engine manifold lines to prevent fuel boiling

3. Regulates fuel mixture during operation

4. Controls fuel flow into the combustion chamber

The correct answer is: Drains engine manifold lines to prevent fuel boiling

A dump valve is a critical component in a gas turbine engine's fuel system, specifically designed to help manage fuel lines and prevent potential issues such as fuel boiling. When the engine is not operating or during certain conditions where fuel is not needed in the manifold, the dump valve opens to allow the fuel to drain from the engine manifold lines. This draining action helps to maintain an optimal temperature within the fuel system. By preventing fuel from remaining stagnant in the lines, it minimizes the risk of boiling, which can adversely affect fuel flow and combustion efficiency. Additionally, boiling fuel can lead to vapor lock, which could impair engine performance or even cause engine failure. This function is essential for ensuring reliable engine performance, particularly in situations where the engine experiences changes in operating conditions, temperature, and pressure. The importance of the dump valve is underscored by its role in maintaining the integrity of the fuel system across various operational scenarios.