AMT Powerplant Theory and Maintenance Questions and Answers

Question 1

During a ground run of a gas turbine engine, a technician observes that the engine lights up, but the RPM fails to accelerate to idle, stabilizing at a lower-than-normal speed.
The EGT is observed to be rising, but may not have exceeded limits yet.
This condition is known as a:

Accepted Answer

Hung start

Answer

Hot start

Answer

Wet start

Answer

False start

Question 2

What is the primary function of the diffuser section in a centrifugal flow gas turbine engine?

Accepted Answer

To decrease the velocity and increase the static pressure of the air.

Answer

To increase the velocity and decrease the pressure of the air.

Answer

To mix the fuel and air for combustion.

Answer

To straighten the airflow before it enters the turbine section.

Question 3

A technician is troubleshooting a reciprocating engine that is consistently backfiring through the induction system during idle. Which of the following is the most likely cause?

Accepted Answer

An excessively lean idle mixture.

Answer

An excessively rich idle mixture.

Answer

A stuck-open exhaust valve.

Answer

Incorrectly gapped spark plugs.

Question 4

For a turbocharged reciprocating engine, what is meant by the term 'critical altitude'?

Accepted Answer

The maximum altitude at which a turbocharger can maintain a rated sea-level manifold pressure.

Answer

The maximum altitude at which the engine can produce 50% of its rated sea-level power.

Answer

The highest altitude the aircraft is certified to fly.

Answer

The altitude at which the turbocharger waste gate is fully open.

Question 5

A maintenance technician inspects a magnetic chip detector removed from a gas turbine engine's oil system and finds several small, metallic particles. This discovery is a primary indicator of what condition?

Accepted Answer

Wear or failure of internal ferrous components like gears or bearings.

Answer

Oil contamination from an external source.

Answer

Normal operation and requires no action.

Answer

Coking and carbon buildup in the lubrication system.

Question 6

What is the primary purpose of the small vent holes found on aircraft magneto housings?

Accepted Answer

To allow for the draining of corrosive gases and moisture.

Answer

To provide cooling airflow over the internal components.

Answer

To act as an inspection port for viewing breaker point alignment.

Answer

To equalize pressure with the crankcase.

During a ground run of a gas turbine engine, a technician observes that the engine lights up, but the RPM fails to accelerate to idle, stabilizing at a lower-than-normal speed.The EGT is observed to be rising, but may not have exceeded limits yet.This condition is known as a:

During a ground run of a gas turbine engine, a technician observes that the engine lights up, but the RPM fails to accelerate to idle, stabilizing at a lower-than-normal speed.
The EGT is observed to be rising, but may not have exceeded limits yet.
This condition is known as a: