15.14 EXHAUST GAS TEMP/INTERSTAGE TURBIE TEMPN

Question 1

Why do gas turbine engines require an exhaust gas temperature (EGT) indication

Answer 1

Monitor high temp experienced by turbine engines to prevent thermal damage

Question 2

Where is the highest temperature located

Answer 2

• directly behind combust chamber

Question 3

Explain turbine inlet temp

Answer 3

• hot gas hits high pressure turbine

Question 4

Explain the exhaust gas temperature (EGT) indicator

Answer 4

• shows average temp measured by the individual thermocouples

Question 5

Explain turbine inlet temperature

Answer 5

• visual indication at instrument panel of the temperature of gases entering the turbine

Question 6

Explain performance indications

Answer 6

• also known as primary indications
• monitor performance, limits of engine, and set thrust for different flight phases

Question 7

Explain system indications

Answer 7

• also called secondary indications
• monitor oil or fuel systems
• also used to detect malfunctions quickly

Question 8

Explain engine trend monitoring

Answer 8

• done on ground to detect engine problems at an early stage
• Uses engine parameters that are automatically recorded by aircraft condition monitoring system (ACMS)

Question 9

What are the 2 engine performance indications

Answer 9

• rotational fan speed (N1)
• Engine pressure ratio (EPR)

Question 10

Explain engine system indications (secondary engine indications)

Answer 10

• monitor correct operation of engine systems
  E.g. for oil system -> monitors quantity,pressure temp etc

Question 11

Advantage of engine trend monitoring

Answer 11

Alerts operator to a problem at an early stage

Question 12

To determine EPR, where are the measurements taken from

Answer 12

• engine inlet
• and turbine exhaust

Question 13

What does it mean if there is a AMBER/RED line indication on EPR DISPLAY

Answer 13

• shows maximum available thrust

Question 14

What does the BLUE circle show on EPR display

Answer 14

• corresponds to the actual throttle position

Question 15

Explain flexible take-off

Answer 15

• uses minimum thrust possible to take off depending on ambient temperature
• reduces engine wear

Question 16

What does the oil pressure indicator show

Answer 16

• engine oil pump discharge pressure

Question 17

Why is it important to have a oil pressure indicator

Answer 17

• prevent engine failure from inadequate lubrication and cooling

Question 18

What are the main 2 types of oil pressure transmitters

Answer 18

• Bourdon tube type
• Strain gauge type

Question 19

Explain low oil pressure switch

Answer 19

• oil pressure under limit
• low oil switch closes
• signal sent to flight display as a warning

Question 20

Explain oil inlet temperature indicator

Answer 20

• Used to indicate the temperature of oil as it enters the oil pressure pump

Question 21

What is the primary component responsible for measuring engine oil temperature

Answer 21

• oil temperature sensor
• Resistance temperature detector (RTD) most common in aircraft engines

Question 22

Most turbine powered aircraft use a low pressure warning switch which is located where

Answer 22

Outlet of each fuel boost pump

Question 23

A low fuel temperature can be corrected with the use of what component

Answer 23

• fuel heater

Question 24

The fuel flow indicating system provides 2 different indications to the flight crew which are

Answer 24

• actual fuel flow to engines
• fuel used since engine was started

Question 25

Explain fuel flow transmitter

Answer 25

Measures mass flow of fuel between fuel control unit and fuel nozzle

Question 26

Explain synchronous mass flow (fuel flow transmitter)

Answer 26

- turns turbine against spring and deflection angle is measured - impeller rotates continuously by electric motor

Question 27

Explain motorless mass flow

Answer 27

- do not require electric motor - use fuel itself to generate acceleration - fuel flow turns small turbine

Question 28

How is the engine rotor speed expressed

Answer 28

- as a percentage of a 100% design speed

Question 29

Each rotor speed indication has 3 main parts

Answer 29

- sensor - data transmission - indication

Question 30

Explain variable reluctance sensor

Answer 30

- known as magnetic reluctance sensor / magnetic pickup - detects change in magnetic flux - phonic wheel/fan blades alter magnetic circuit

Question 31

Explain tachometer generator

Answer 31

- has permanent magnet that is driven by gearbox with speed proportional to N2 - generates 3-phase AC voltage

Question 32

What are the 3 different types of rotor speed indications

Answer 32

- display with clock-type scale - display with moving vertical bar - classical electromechanical indicator

Question 33

What occurs if N1 redline limit is exceeded on modern engines

Answer 33

- speed and duration of overspeed is recorded and initiates a report from engine trend monitoring

Question 34

What are the main parts of the engine vibration monitoring system

Answer 34

- FD indication 0-6 - 1 or 2 vibration sensors - computer that collects and filters vibration data for indicating

Question 35

Explain vibration sensors (accelerometer)

Answer 35

- measure the radial acceleration of the rotor system - 2 sensors ( one located in compressor, another in turbine area)

Question 36

What are the 2 types of accelerometers used on engines to measure vibration

Answer 36

- electromagnetic accelerometer - piezoelectric- crystal type sensor

Question 37

What are the 2 types of accelerometers used on engines to measure vibration

Answer 37

- electromagnetic accelerometer - piezoelectric- crystal type sensor

Question 38

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