Engine Indication and Monitoring (vibration, EGT, trend monitoring)
What this domain tests
Engine Indication and Monitoring covers EGT, N1/N2, vibration, and trend monitoring. The exam tests how parameters are interpreted, what exceedances mean, and how trends detect deterioration.
Core rules
- EGT is a turbine-temperature indicator; it is used for takeoff limits, start limits, and trend monitoring. EGT margin is the difference between the observed value and the limit.
- Vibration is measured in velocity, displacement, or acceleration; fan imbalance gives a once-per-rev signal; broadband vibration suggests bearing or accessory problems.
- Trend monitoring compares baseline and current values of EGT, fuel flow, N2, and vibration at a fixed power setting. A rising EGT trend at constant thrust suggests deterioration.
- Exceedance records and chip detectors are part of condition monitoring; they are not flight-deck control parameters.
Worked example
At a fixed cruise Mach and altitude, baseline EGT is 720 C; current EGT is 745 C. The EGT margin has fallen by 25 C. If the limit is 800 C, remaining margin is 55 C. The reasoning: trend shift, not a single reading, identifies deterioration; a 25 C shift may indicate compressor fouling, a sensor error, or hot-section distress, so it needs confirmation, not immediate removal.
Traps
Treating EGT as turbine inlet temperature; confusing vibration units; using a single exceedance as a trend; ignoring sensor bias; assuming a redline is the same as a trend limit.