Powerplant Systems & Engine Maintenance Flashcards

An engine-driven fuel pump has a relief valve. What is the purpose of this valve?

Answer: To bypass excess fuel back to the inlet when outlet pressure exceeds the set value

The relief valve in an engine-driven fuel pump bypasses excess fuel back to the pump inlet to maintain a constant, regulated outlet pressure.

What condition is indicated when a turbine engine's exhaust gas temperature (EGT) is higher than normal at a given power setting?

Answer: Possible turbine damage, compressor fouling, or deterioration reducing engine efficiency

High EGT at a given power setting suggests reduced engine efficiency from causes such as compressor fouling, turbine damage, or bleed air leaks, requiring investigation.

Detonation in a reciprocating engine is best defined as:

Answer: Explosive, uncontrolled burning of the fuel-air mixture after normal ignition

Detonation is the sudden, explosive auto-ignition of the end gas in the cylinder after normal spark ignition, producing damaging pressure spikes.

When performing a magnetic particle inspection on engine steel components, what type of defects can this method detect?

Answer: Surface and near-surface discontinuities in ferromagnetic materials

Magnetic particle inspection reveals surface and near-surface cracks or discontinuities in ferromagnetic (iron/steel) components by attracting iron particles to flux leakage points.

What is the function of the pressurization and dump valve in a gas turbine fuel system?

Answer: Prevents secondary fuel nozzles from opening until primary fuel pressure is sufficient, and dumps manifold fuel on shutdown

The pressurizing and dump valve holds back fuel from secondary nozzles until pressure is adequate for proper atomization, then drains the fuel manifold when the engine shuts down to prevent coking.

Which type of oil system is used on most gas turbine engines to ensure continuous lubrication during unusual flight attitudes?

Answer: Dry-sump pressure-feed system with a dedicated oil tank

Gas turbine engines use a dry-sump system with a dedicated tank and pressure-fed lubrication so oil supply is not affected by aircraft attitude changes.

What is 'compressor surge' in a turbine engine?

Answer: A disruption of airflow through the compressor causing rapid, repetitive flow reversal and loud banging

Compressor surge is an aerodynamic instability in which airflow through the compressor reverses rapidly, causing loud bangs, power loss, and potential damage.