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64.26 Turbine Engine Indicating and Instrumentation
64.26.2 Describe the following types of turbine engine indicators and instrumentation including their function and basic principles of operation—
(a) engine rpm
Engine RPM indicator measures the rotational speed of the engine's rotating components, such as the compressor and the turbine.
The indicator works by measuring the frequency of the electrical signal generated by a sensor that senses the rotational speed of the engine.
The frequency of the signal is proportional to the RPM of the engine.
(b) engine pressure ratio
Engine Pressure Ratio (EPR) is the ratio of the pressure at the engine inlet to the pressure at the engine exhaust.
The EPR indicator measures this ratio and provides an indication of the engine's thrust output.
The indicator works by measuring the pressure at the engine inlet and the pressure at the engine exhaust and then calculating the ratio of the two pressures.
(c) engine torque
Engine torque is the twisting force that the engine produces at the output shaft.
The engine torque indicator measures the torque produced by the engine and provides an indication of the engine's power output.