15.21 Operation and Monitoring Flashcards
(58 cards)
What are common reasons for running a turbine engine on the ground?
Fault diagnosis, post-maintenance checks, engine deterioration, control linkage checks, repositioning aircraft, or system taxi checks.
What are the sources of air for engine starting?
APU, external ground power unit (GPU), or bleed air from another engine.
What key parameters must be monitored during engine start?
: Engine speed (N1/N2), oil pressure, and EGT.
What must be checked before starting a turbine engine?
Engine intakes/exhausts for FOD, oil/fuel levels, panel security, undercarriage down and locked, and clear ground area (10m in front, aircraft-specific distance behind).
Why is the aircraft positioned into wind before engine start?
To improve airflow into the engine and reduce the risk of hot starts or FOD ingestion.
What safety measures are required during an engine ground run?
Apply brakes, fit chocks, fire extinguisher on hand, wear ear protection, maintain flight deck communication, and restrict access to engine danger zones.
When may the fire service be required during engine runs?
If cowlings are open or for high-power/pressure runs—depends on local airport rules.
What’s the purpose of allowing an engine to idle before shutdown
To cool it down and prevent rotor seizure after high-power operation.
How is a turbine engine shut down after ground running?
Retard thrust lever to idle, then move fuel cut-off lever to OFF.
What is EPR and what does it indicate?
Engine Pressure Ratio – it measures jet pipe pressure vs inlet pressure to indicate thrust output.
This is for centrifugal compressor
What does the N1 rotor speed represent?
Speed of the low-pressure spool.
Why is EGT a critical engine parameter?
It helps detect overheating; exceeding red line requires immediate inspection.
How do turboprop- turboshaft engines measure power output?
- using torque indicators
How is turboprop/ shaft engine power output displayed?
Torque oil pressure (in psi)
Torque percentage
Sometimes a direct horse-power read-out
In turboprop/ shaft where does the torque meter get its input from?
Torque sensing unit in the engine
What are the types of torque sensing system sused in turboprop/shaft engines#?
Hydromechanical: converts engine oil pressure to a torque signal
Electronic: converts twist of the power output shaft into a torque signal
Phase displacement: One shaft is reference, second is allowed to twist. Phase difference tells you how much torque engines producing
Why can’t axial bypass engines use RPM for thrust measurement?
Because ambient conditions affect thrust, so RPM doesn’t directly reflect power output.
What was used in early axial engines to estimate thrust?
A pressure comparison between ambient pressure (Pamb) and exhaust pressure (P7), in inches of mercury.
What system collects engine performance data in modern aircraft?
Aircraft Condition Monitoring System (ACMS).
What is the role of FADEC in trend monitoring?
It measures engine parameters and sends them to the data system.
What are the three types of ACMS reports?
Routine, on-request, and advisory reports.
What is the purpose of thermodynamic analysis?
To identify which engine module is causing performance changes.
What is mechanic-dynamic analysis used for?
To identify vibration-related faults using filtered sensor signals.
What is the function of the Data Management Unit (DMU)?
To compile and transmit ACMS reports.
