FM 1-506 Fundamentals of Aircraft Power Plants ... - Survival Books

WWW.SURVIVALEBOOKS.COMFM 1-506magnet and wire coil. They produce a pulse of currenteach time a shaft or reference tooth passes (Figure 9-3).TORQUEMETER INDICATING SYSTEMOnly a small part of the propulsive force producedby a turboprop is caused by jet thrust. Neither turbinespecialized oil pressure tap on the engine inlet housingand to a vent connection on the accessory drive gearboxThe 28-volt AC system operates the electrical circuit.The Lycoming (T-55-L-712) torquemeter, a refinedtorque measuring system, comprises five componentsand interconnecting wiring. Two of these, the powerdischarge pressure nor engine pressure ratio is used toindicate power produced by the engine. Instead a torquemetermeasures the power level that the enginedevelops on the ground and in flight. Consult the enginemaintenance manual for a description of torquemetersystem functions. In most systems, however, torquemeteroil pressure is used to actuate a torque indicating instrumentin the aircraft. The torquemeter instrumentportrays torquemeter oil pressure (which is proportionalto engine power) in pounds per square inch. Sometorquemeter instruments are calibrated to read poundfeetof torque. Some may read shaft horsepower directly(Figure 9-4).One torquemeter indicating system sometimescalled a torque pressure indicating system, contains apressure-indicator-type instrument. It provides continuousreading of engine output shaft torque supplied byan electrical transmitter mounted on the engine inletsection. The transmitter is connected by hoses to a9-3