Final answer:
Tachometers in gas turbine engines are calibrated using a reference device to ensure accurate engine RPM readings across the entire operating range for safe and efficient operation.
Step-by-step explanation:
The question 'How are gas turbine engine tachometers calibrated?' relates to the field of Engineering, as it involves the procedures and principles of instrumentation calibration specific to aerospace or mechanical engineering. Gas turbine engine tachometers are calibrated meticulously to measure engine speed with precision. The calibration process includes setting the tachometer to accurately reflect the engine RPM (revolutions per minute), which is crucial for the safe and efficient operation of the engine. During calibration, a standard reference device with a known accuracy is used to verify the readings of the tachometer. The tachometer is adjusted until its readings match those of the reference device across the entire operating range of the engine. The calibration ensures that the voltage output of the sender units accurately corresponds to the RPMs, similar to how the voltmeters in a 1996 Volkswagen measure voltage output to determine fuel levels and engine temperature.