Instrumentation Flashcards
What does the engine RPM sensor consist of?
It monitors compressor RPM normally as a percentage.
Uses tacho generators or hall effect transducer
Feeds speed info to central processor and then electronic signals to the cockpit
What is the engine pressure ratio?
Indicates power (thrust) It is a ratio of inlet pressure to jet pipe pressures
What is a torque indicating system?
“torque meter”
Engine torque is used to indicate the power that is developed by a turboprop or turboshaft engine.
Engine torque of the motor is proportional to horsepower transmitted through the propeller.
Displayed in: PSI, Ft/lbs, %, HP
What are the two types of torque sensing systems?
Hydromechanical type - Converts oil pressure into a torque signal.
Electronic type - which converts the twisting of the power shaft under torque into an electrical signal.
Explain the turbine Temperature indicating system
Monitors the temperature of the turbine, through thermocouple probes which are mounted in various stages of the gas stream. Creates a small voltage and can be measured and displayed in the cockpit
An automatic gas stream control system is usually provided to ensure that the maximum gas temperature is not exceeded.
Explain the thermocouples how they measure the temperature of the gases and transmit it to the cockpit?
They consist of two wires joined together in a metal-safe gaurd tube. Transfer holes allow the gas to flow across the junction and the temperature is measured. From the multiple probes positioned in the gas stream, they obtain an average that is shown to the cockpit.
What are the materials of the thermocouple wires?
Nickel chromium and Nickel aluminum alloys
How is oil temperature/pressure measured?
Sensed by a temperature-sensitive element fitted in an oil system. A change in temperature/pressure causes a change in resistance and the corresponding change in indication.
How is fuel temperature and the pressure monitored?
Electrically transmitted
How is fuel flow measured?
through a transmitter that measures the fuel flow electrically and sends a signal to the indicator.
How are engine vibrations monitored?
Through piezoelectric accelerometers mounted around the engine, and displayed through the EICAS window.
