15.14 EXHAUST GAS TEMP/INTERSTAGE TURBIE TEMPN Flashcards
Why do gas turbine engines require an exhaust gas temperature (EGT) indication
Monitor high temp experienced by turbine engines to prevent thermal damage
Where is the highest temperature located
- directly behind combust chamber
Explain turbine inlet temp
- hot gas hits high pressure turbine
Explain the exhaust gas temperature (EGT) indicator
- shows average temp measured by the individual thermocouples
Explain turbine inlet temperature
- visual indication at instrument panel of the temperature of gases entering the turbine
Explain performance indications
- also known as primary indications
- monitor performance, limits of engine, and set thrust for different flight phases
Explain system indications
- also called secondary indications
- monitor oil or fuel systems
- also used to detect malfunctions quickly
Explain engine trend monitoring
- done on ground to detect engine problems at an early stage
- Uses engine parameters that are automatically recorded by aircraft condition monitoring system (ACMS)
What are the 2 engine performance indications
- rotational fan speed (N1)
- Engine pressure ratio (EPR)
Explain engine system indications (secondary engine indications)
- monitor correct operation of engine systems
E.g. for oil system -> monitors quantity,pressure temp etc
Advantage of engine trend monitoring
Alerts operator to a problem at an early stage
To determine EPR, where are the measurements taken from
- engine inlet
- and turbine exhaust
What does it mean if there is a AMBER/RED line indication on EPR DISPLAY
- shows maximum available thrust
What does the BLUE circle show on EPR display
- corresponds to the actual throttle position
Explain flexible take-off
- uses minimum thrust possible to take off depending on ambient temperature
- reduces engine wear
What does the oil pressure indicator show
- engine oil pump discharge pressure
Why is it important to have a oil pressure indicator
- prevent engine failure from inadequate lubrication and cooling
What are the main 2 types of oil pressure transmitters
- Bourdon tube type
- Strain gauge type
Explain low oil pressure switch
- oil pressure under limit
- low oil switch closes
- signal sent to flight display as a warning
Explain oil inlet temperature indicator
- Used to indicate the temperature of oil as it enters the oil pressure pump
What is the primary component responsible for measuring engine oil temperature
- oil temperature sensor
- Resistance temperature detector (RTD) most common in aircraft engines
Most turbine powered aircraft use a low pressure warning switch which is located where
Outlet of each fuel boost pump
A low fuel temperature can be corrected with the use of what component
- fuel heater
The fuel flow indicating system provides 2 different indications to the flight crew which are
- actual fuel flow to engines
- fuel used since engine was started
Explain fuel flow transmitter
Measures mass flow of fuel between fuel control unit and fuel nozzle
Explain synchronous mass flow (fuel flow transmitter)
- turns turbine against spring and deflection angle is measured
- impeller rotates continuously by electric motor
Explain motorless mass flow
- do not require electric motor
- use fuel itself to generate acceleration
- fuel flow turns small turbine
How is the engine rotor speed expressed
- as a percentage of a 100% design speed
Each rotor speed indication has 3 main parts
- sensor
- data transmission
- indication
Explain variable reluctance sensor
- known as magnetic reluctance sensor / magnetic pickup
- detects change in magnetic flux
- phonic wheel/fan blades alter magnetic circuit
Explain tachometer generator
- has permanent magnet that is driven by gearbox with speed proportional to N2
- generates 3-phase AC voltage
What are the 3 different types of rotor speed indications
- display with clock-type scale
- display with moving vertical bar
- classical electromechanical indicator
What occurs if N1 redline limit is exceeded on modern engines
- speed and duration of overspeed is recorded and initiates a report from engine trend monitoring
What are the main parts of the engine vibration monitoring system
- FD indication 0-6
- 1 or 2 vibration sensors
- computer that collects and filters vibration data for indicating
Explain vibration sensors (accelerometer)
- measure the radial acceleration of the rotor system
- 2 sensors ( one located in compressor, another in turbine area)
What are the 2 types of accelerometers used on engines to measure vibration
- electromagnetic accelerometer
- piezoelectric- crystal type sensor
What are the 2 types of accelerometers used on engines to measure vibration
- electromagnetic accelerometer
- piezoelectric- crystal type sensor
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