AMT Powerplant Theory and Maintenance 3

Question 1

Which statement about pre-ignition in a reciprocating engine is correct?

Accepted Answer

Pre-ignition occurs before the spark plug fires and can cause engine damage

Answer

Pre-ignition occurs when the fuel-air charge ignites before the spark plug fires, often due to a hot spot, and can cause severe engine damage.

Question 2

The compressor pressure ratio of a turbine engine is defined as:

Accepted Answer

Compressor outlet total pressure divided by compressor inlet total pressure

Answer

Compressor pressure ratio is the ratio of total air pressure at the compressor outlet to total air pressure at the compressor inlet, indicating compression efficiency.

Question 3

A reciprocating engine has excessive blow-by past the piston rings. Which instrument indication would you expect?

Accepted Answer

Increased oil consumption and crankcase pressure

Answer

Blow-by allows combustion gases to pass the piston rings into the crankcase, causing increased crankcase pressure and oil consumption.

Question 4

During turbine engine ground run-up, a 'hung start' is characterized by:

Accepted Answer

RPM stabilizing below idle with exhaust temperature continuing to rise

Answer

A hung start occurs when the engine lights off but RPM stabilizes at a sub-idle value while EGT continues to rise, risking a hot start.

Question 5

What does the term 'specific fuel consumption' (SFC) describe in turbine engines?

Accepted Answer

The pounds of fuel burned per hour per pound of thrust produced

Answer

Specific fuel consumption (SFC) is the ratio of fuel flow (lb/hr) to thrust produced (lb), measuring how efficiently an engine converts fuel into thrust.

(AMT) Aviation Maintenance Technician Practice Test

(AMT) Aviation Maintenance Technician Practice Test

AMT Powerplant Theory and Maintenance 3