Module 15.14 Engine indication systems

Question 1

Where is EGT measure from?

Answer 1

After the HP turbine or after the LP turbine

Question 2

Why do we take the EGT?

Answer 2

As we want to know the Turbine Inlet Temperature (TIT) but the 1st nozzle guide vane is too hot to measure temperature at the point

Question 3

TIT is not easy to read as it can be above what temperature?

Answer 3

1400℃

Question 4

What improves the accuracy of the calculations of TIT?

Answer 4

Placing the EGT sensor after the HP turbine

Question 5

What does the EGT indicator in the flight deck show?

Answer 5

The average temperature measured by the thermocouples

Question 6

What does the instrument scale range from?

Answer 6

0 to 1200℃

Question 7

What are dual thermocouples?

Answer 7

Two electrically independent junctions within a single probe

Question 8

Digital flight deck instrumentation does not use what to give temperature information to the crew?

Answer 8

• Resistance type indicators
• Adjusted servo-driven thermocouples

Question 9

What does EPR stand for?

Answer 9

Engine Pressure Ratio

Question 10

What are the two types of engine performance indicators?

Answer 10

• N1, rotational speed of the fan
• Engine Pressure Ratio (EPR)

They give an equivalent value

Question 11

Engine indication can be divided into what 3 groups?

Answer 11

• Performance indications
• System indications
• Engine trend indications

Question 12

What are the primary indications?

Answer 12

• N1
• EPR
• N2/N3
• EGT
• Fuel Flow (FF)

Question 13

What warnings and cautions are displayed on the EICAS/ECAM?

Answer 13

• Indication exceeds limit
• Low oil pressure
• Clogged filter
• Unlocked thrust reverser

Question 14

What are the 3 types of analysis done?

Answer 14

• Thermodynamic
• Mechanic dynamic
• Oil consumption

Question 15

What does EPR compare?

Answer 15

Compares engine turbine discharge pressure to the pressure of the ram air at the inlet

Question 16

What does the blue circle represent on the EPR display?

Answer 16

EPR compared to the throttle position

Question 17

What does the amber/red represent on the EPR display?

Answer 17

Max available thrust

Question 18

What is the purpose of Flexible Take Off/Assumed Temperature Derate?

Answer 18

Uses an assumed temperature thrust reduction to preserve wear and prolong life

Question 19

Where is oil pressure measured?

Answer 19

After the pump

Question 20

What happens to the bourdon tube profile as pressure enters the tube?

Answer 20

Oval to a circle

Question 21

What is the most common arrangement of a strain gauge?

Answer 21

Wheatstone bridge configuration

Question 22

What does a strain gauge measure?

Answer 22

Change in resistance

Question 23

When there is no strain, what is the voltage across the Wheatstone bridge?

Answer 23

0, balanced

Question 24

What is the oil pressure switch connected to?

Answer 24

• Oil supply line
• Oil tank vent line

Question 25

Where does the oil pressure signal get sent to?

Answer 25

Flight warning computer

Question 26

What are the most common type of temperature sensors?

Answer 26

- Resistance temperature detector - Thermocouple

Question 27

Where is oil temperature measured?

Answer 27

As oil enters the pump

Question 28

Where is the low pressure sensor in the fuel system?

Answer 28

After the LP pump

Question 29

What sensor is fitted across the filter?

Answer 29

Differential pressure

Question 30

What aircraft utilise bourdon tubes?

Answer 30

Small reciprocating aircraft

Question 31

What is sued alongside the gauge indications for warnings?

Answer 31

Visual and audible warnings

Question 32

Low fuel pressure warning lights are illuminated using what?

Answer 32

Simple pressure sensing switches

Question 33

When do the switch contacts close?

Answer 33

When there is not enough pressure to hold open the diaphragm

Question 34

Where is the low pressure warning switch usually located?

Answer 34

Outlet of the fuel boost pump

Question 35

How can low fuel temperature be corrected?

Answer 35

Fuel heater if equipped

Question 36

The fuel temperature can be integrated into what?

Answer 36

The fuel flow processing calculations

Question 37

What two indications does the fuel flow indication system display?

Answer 37

- Actual fuel flow to the engines - Fuel used by the engines since the start

Question 38

What is required to generate fuel flow and fuel used indications?

Answer 38

Fuel flow transmitters

Question 39

What law do the fuel flow transmitters utilise?

Answer 39

Newton's 2nd law

Question 40

What do all transmitters measure?

Answer 40

Force applied by the mass of fuel

Question 41

What are the types of flow meters?

Answer 41

- Synchronous mass flow - Motorless mass flow

Question 42

What measures the force in the synchronous mass flow meter?

Answer 42

Fuel mass turns a turbine against a spring, deflection angle corresponds to the force

Question 43

In a motorless mass flow meter, what is used to generate acceleration?

Answer 43

Turbine driven by fuel itself

Question 44

What does the rotating turbine drive? (motorless)

Answer 44

Drum and impeller

Question 45

How are the drum and impeller coupled?

Answer 45

By a spring

Question 46

What are the 2 types of turbine engine speed sensor?

Answer 46

- Variable reluctance - Tachometer generator

Question 47

Where is the variable reluctance probe placed?

Answer 47

- On the fan blades - Phonic wheel

Question 48

What spool is a variable reluctance sensor on?

Answer 48

N1

Question 49

Tachometer generator frequency is proportional to what?

Answer 49

N2 rotor speed

Question 50

The 3 phase generator output of the tachometer supplies power to what?

Answer 50

FADEC computer

Question 51

What are the 3 types of rotor speed indication?

Answer 51

- Clock type scale - Moving vertical bar - Electromechanical indicator

Question 52

If the engine speed exceeds the N1 redline limit what is initiated?

Answer 52

Generation of a report from engine trend monitoring

Question 53

How is the vibration indication given?

Answer 53

Units from 0 to 6

Question 54

What does EVMU stand for?

Answer 54

Engine Vibration Monitoring Unit

Question 55

Where are the sensors on each engine located?

Answer 55

- Compressor area - Turbine area

Question 56

What are 2 accelerometer types used to measure vibrations?

Answer 56

- Electromagnetic accelerometer - Piezoelectric crystal type sensor

Question 57

If N1 or N2 speed signal is lost what will be shown?

Answer 57

BroadBand (BB)

Question 58

The computerised engine fan balancing system helps to do what?

Answer 58

Change or decrease vibration

Question 59

Torque meters give engine power in what engines?

Answer 59

Turboshaft

Question 60

How do torque meters measure torque?

Answer 60

- Electrically - Hydraulically

Question 61

How is a reading obtained on a torque meter?

Answer 61

Concentric shafts. Twist between the inner and outer shaft, the twist is proportional to the torque

Question 62

How is an electric torque reading produced?

Answer 62

Relative movement between teeth and magnet

Question 63

How do hydraulic torque meters give a reading?

Answer 63

Movement opens a valve. Oil pressure is proportional to the torque

Question 64

What is the purpose of the power assurance test?

Answer 64

Check engine can accelerate and decelerate in a certain time

Question 65

How long should the engine be held at idle for initially?

Answer 65

5 mins

Question 66

If above 70% N1 is achieved during the test, how long post test must the engine be run at idle?

Answer 66

10 mins

Question 67

What switches should be set too off in a power assurance test?

Answer 67

Anti-ice and bleed air

Question 68

How is N2 rotor speed found?

Answer 68

Output from a Permanent Magnet Generator