15.14 Engine Indication Systems Flashcards
What do all gas turbine engines require?
An exhaust gas temperature (EGT) indication
Where would a low pressure sensor for fuel be positioned?
After the outlet for the low pressure filter
Why could low fuel pressure occur ?
Can originate from cavitation caused by high fuel pump demand
What is an exhaust gas temperature monitor for?
To monitor the high temps experienced by the turbine engines to prevent thermal damage and indicate when a limit is exceeded
What are fuel pressure sensors on filters used for ?
To give warning of an impending filter blockage and risk of cavitation
Where will an indication for low fuel pressure be displayed?
As a warning lamp or as an EICAS status message
There must be an indication that the fuel system is delivering to where ?
That there is flow to the fuel metering device
Where is the highest temperature on an engine?
Directly behind the combustion chamber where hot gas hits the high pressure turbine
There must be an indication that the fuel system is delivered to where ?
What is the highest temperature on an engine called?
Turbine inlet temperature (TIT)
Where is the exhaust gas temperature measured?
In a much colder location either between the high and low pressure turbine or directly behind the low pressure turbine
What do light aircraft use to read fuel pressure ?
A direct reading bourdon tube pressure gauge
What should a direct reading bourdon tube pressure gauge be connected to ?
A fuel line
What are the 5 relative temperatures used to monitor temperature?
Exhaust Gas Temperature (EGT), Turbine Inlet Temperature (TIT), Turbine Gas Temperature (TGT), Interstage Turbine Temperature (ITT), and Turbine Outlet Temperature (TOT)
How may modern complex aircraft read fuel pressure ?
Using a pressure transducer which sends electric signals to the flight deck
What makes up an electrical torque meter system
Torque meter assembly, a phase detector and an indicator
Where are temperature thermocouples placed?
Inserted at the turbine discharge, the temperature provides a relative indication of the temperature at the inlet
If an aircraft is equipped with an auxiliary pump, what does the fuel pressure gauge indicate ?
The auxiliary pump pressure until the engine is started, then the gauge will indicate pressure created by the EDP
Several thermocouples are usually used, spaced at intervals, where are these?
Around the perimeter of the engine exhaust duct near the turbine exit
What does the EGT indicator show in the flight deck?
Average temperature measured by the individual thermocouples
What does the EGT indicator show in the flight deck?
Average temperature measured by the individual thermocouples
Complex reciprocating engined aircraft may use a differential fuel pressure gauge, what are the two values this gauge compares ?
Fuel inlet pressure to air inlet pressure at the fuel metering device
What do the temperature scales range from?
0°C to 1200°C
When an aircraft has sensors that output signals, where is this data processes for display?
Instrument gauge microprocessor or a computer
What is twist in the drive shaft from the engine to the gearbox proportional to in a torque meter
Torque
What does a turbine inlet temperature system provide?
A TIT indicating system provides a visual indication at the instrument panel of the temperature of gases entering the turbine
What does an electric torque meter use to measure torque
Magnet
What happens to the contacts of a pressure sensing switch when there is low fuel pressure ?
Contacts create a circuit as there is insufficient pressure to hold them open, causing lights or annunciations to switch on
What do turbine powered aircraft use to indicate low fuel pressure ?
A low pressure switch at the outlet of each fuel boost pump
What do dual thermocouples consist of?
Dual thermocouples exist containing two electrically independent junctions within a single probe
Why should fuel temperature be monitored ?
Allows indication to the flight crew when temperature is causing ice to form in the fuel system and especially filters
Engine indications are used to monitor the parameters of the engine and its systems. What are the three groups?
Performance indications - also named primary indications- are used to monitor the performance and the limits of the engine and to set the thrust for the different flight phases
System indications - also called secondary indications- are used to monitor the operation of engine systems such as the oil or fuel system. They are also used to detect malfunctions quickly.
Engine trend monitoring - not usually shown in the flight deck, is done on the ground to detect engine problems at an early stage. It uses engine parameters that are automatically recorded by the Aircraft Condition Monitoring System (ACMS)
What is the most common fuel temperature sensor for large High performance turbine aircraft ?
Resistance type electric fuel temperature sender in the main tank
What are the two ways of measuring engine thrust?
Rotational speed of the fan called N1, engine pressure ratio (EPR)
How does a hydraulic torque meter work?
Uses engine oil pressure controlled by a gear in response to applied torque. This year moves a piston which controls the oil pressure flow
Where are the signals from the resistance type electric fuel temperature sender sent to ?
A ratiometer gauge or through a computer for processing and digital display
What are the other engine performance indications?
Engine rotor speed indication for each rotor system
Exhaust gas temperature (EGT)
Fuel flow indication
What is the pressure in the hydraulic torque meter equal to
Torque in the shaft
How can low fuel temperature be corrected ?
Use of a fuel heater
What are used to measure the other performance indications?
N1, N2 and N3 if available
What are the secondary engine indications?
Used to monitor the operation of the engine systems
What are the indications for the oil system?
More to the oil quantity, oil pressure and oil temperature
How can viscosity of fuel due to temperature effect readings and how can it be accounted for ?
Viscosity affects fuel flow sensing accuracy which can be accounted and corrected by flow processing calculations in a computer