Turbine Engine Indicating And Instrumentation Flashcards
Describe the following types of turbine engine indicators and instrumentation including their function and basic principles of operation—
(a) engine rpm
Usually indicated for each spool in the engine. Can use a three phase AC generator and synchronous indicator pairing.
Also uses a inductive sensor which works by having a magnet and electric sensor at a point and having the fan blade pass that point and as it passes, the magnetic field is disturbed and the sensor counts when this happens and transmits it to display.
Describe the following types of turbine engine indicators and instrumentation including their function and basic principles of operation—
engine torque
Torque is measured at the reduction gear and is proportional to the horsepower developed and transmitted through the shaft to the propeller or transmission gearbox.
Describe the following types of turbine engine indicators and instrumentation including their function and basic principles of operation—
engine pressure ratio and turbofan power ratio
used at the primary indication of engine thrust. EPR comprises the pressure sensed at pitot heads located in the tailpipe exhaust stream compared to pitot heads located at intake.
Turbofan Power ratio is a means of setting indication power as a percentage of the maximum available in each mode
Describe the following types of turbine engine indicators and instrumentation including their function and basic principles of operation—
Fuel flow
Fuel temperature and quality, as well as fuel flow rates are used to calculate the fuel remaining in each tank. This is done by a fuel vane in the fuel line which moves according to the flow rate.
Fuel quantity is measured in weight
Describe the following types of turbine engine indicators and instrumentation including their function and basic principles of operation—
Pressure and temperature indicators (EGT & oil temp)
exhaust gas temperature is measured by thermocouples protruding into the gas stream. Thermocouples are connected in parallel and provide an average gas temperature.
Oil temperature pressure and quantity indicators are normally provided as well.
Describe the following types of turbine engine indicators and instrumentation including their function and basic principles of operation—
Vibration indicators
If there is any vibration outside limits, the engine can easily become damaged, so keeping an eye on this is another way to monitor your engine’s health.
Several accelerometers placed throughout the engine monitor vibration and if these vibrations become too much, a warning in the cockpit will be activated.
State meaning of EPR
Engine Pressure Ratio - difference between turbine discharge pressure and engine inlet pressure. An indication of what the engine has done with the air its scooped.
The EPR reading is used to determine the amount of thrust produced in many turbofan aircraft. The higher the EPR, the more thrust is being produced.
State meaning of fan speed N1 and N2 and N3
N1 is the speed of the low speed spool, which in a turbofan engine is connected to the fan.
N2, in a two spool turbine engine, is the high pressure spool.
N3, triple spool engine, N2 is now IP and n3 HP.
State meaning of TIT
Turbine inlet temp - the temperature of the gases from the combustion section of the engine as they enter the first stage of the turbine.
Most critical of all temp as its the hottest part of engine.
State meaning of ITT
Interstage Turbine Temperature - temperature of exhaust gasses (combustion chamber) between high and low pressure turbines.
Number of thermocouples placed around the perimeter of the engine core are used to measure it.
What is thermocouple
Device devices which produce a small electrical current when heated. They are used on many types of engines, piston and turbine.
What is EGT/TOT/JPT/TGT
Exhaust gas temp, the temp of the exhaust gas as it leaves the turbine unit. Also referred to as Turbine Outlet Temperature or Jet Pipe temperature or Turbine Gas Temp.
