Are aircraft instruments suitable for trimming a turbine engine?

• A. Yes, JetCal is used as the special analyzer/trimmer.
• B. No, a standard compass is sufficient.
• C. No, a special analyzer/trimmer such as a JetCal should be used.
• D. Yes, the flight data recorder can be used for trimming.

Answer: (C)

Trimming a turbine engine requires precise calibration with equipment designed specifically for engine parameters, not the general instruments used in flight. A specialized analyzer/trimmer—such as JetCal—is built to measure and adjust engine performance factors (like fuel metering and timing) under controlled conditions and to verify tolerances. Regular cockpit instruments, like a compass, are for navigation, and a flight data recorder is a data-logging device; neither provides the real-time calibration capability or the accuracy needed to trim an engine. So, use the dedicated analyzer/trimmer designed for this task rather than standard aircraft instruments.