Engines

Question 1

The engines have a ____ starter.

Answer 1

Pneumatic

Question 2

What are the different air sources to start an engine?

Answer 2

1.) APU
2.) Engine Cross-Bleed
3.) Buddy Start

Question 3

5 engine sections

Answer 3

Inlet (includes IPS mounted fwd of compressor
Compressor (6 stage: 5 axial, 1 centrifugal)
Combustor (12 fuel injectors, 2 spark ignitors)
Turbine (4 axial flow turbine wheels)
Exhaust

Question 4

The IPS directs airflow into the ___ and provides mounting for the ____.

Answer 4

Compressor; accessory gearbox

Question 5

What do the first two turbine wheels drive? What signal is given from the first two turbine wheels?

Answer 5

Compressor and AGB ; Ng

Question 6

What do the second two turbine wheels drive? What signal is given from the second two turbine wheels?

Answer 6

MGB ; Np

Question 7

How many thermocouples are there? What signal is generated from thermocouples?

Answer 7

7 ; TGT

Question 8

Np is sensed by two Np sensors in the ___ section of the engine.

Answer 8

Exhaust

Question 9

What four components actually control the engine?

Answer 9

EDECU, HMU, Engine-driven alternator, and fuel flow control valves

Question 10

The HMU controls the gas generator by monitoring what factors?

Answer 10

Acceleration limiting
Stall and flameout prevention
Gas generator speed limiting
Rapid response to power demand
Variable geometry actuation

Question 11

____ trim the HMU to satisfy load requirements to maintain Nr, load sharing, and limit TGT

Answer 11

EDECU

Question 12

What does PCL stand for?

Answer 12

Power Control Lever

Question 13

What are the positions of the PCL?

Answer 13

OFF
IDLE
FLY
LOCKOUT

Question 14

What spindle does the PCL control?

Answer 14

The Power Available Spindle (PAS)

Question 15

How do you enter LOCKOUT?

Answer 15

Advance PCL to LOCKOUT then back to FLY

Question 16

What does LOCKOUT override?

Answer 16

EDECU and the control functions of the EDECU:
Auto TGT governing
Auto Nr governing
Loadsharing

Question 17

What factor is not overridden in LOCKOUT and why?

Answer 17

Overspeed ; overspeed control is an independent function controlled by the overspeed drain valve, not the EDECU

Question 18

How do you cancel LOCKOUT?

Answer 18

Decrease PCL to IDLE then back to FLY

Question 19

What controls the Load Demand Spindle (LDS)?

Answer 19

Collective

Question 20

The engine speed trim switch will increase or decrease what of both engines?

Answer 20

Np

Question 21

What is the adjustment range of the engine speed trim switch? What is it typically set at?

Answer 21

96%-101% ; typically set at 100%

Question 22

What trims fuel to maintain set engine Np?

Answer 22

EDECU

Question 23

What happens if LDS roll pin shears?

Answer 23

LDS cable driven full aft, providing max LDS demand. May produce a Tq split. May be high enough to drive Np/Ng to overspeed limits.

Question 24

Ng overspeed?
Np overspeed?

Answer 24

Ng overspeed: 110 +/- 2%
Np overspeed: 120 +/- 1% (will reset when Np drops below limit)

Question 25

What are the 4 functions of the overspeed drain valve?

Answer 25

1.) Provide fuel to manifolds and 12 injectors 2.) Return fuel back to HMU if Np overspeed solenoid energizes 3.) Purge main fuel manifold overboard after shutdown through SOV and drain valve 4.) Shuts off fuel to prevent hot start by hot start preventer

Question 26

The engine driven alternators three windings independently supply power to what?

Answer 26

1.) EDECU 2.) Ignitor assembly 3.) Ng signal to EICAS

Question 27

What happens when Ng signal generated by engine driven alternator is lost?

Answer 27

No Ng signal on EICAS Red X on respective engine display "No.1/No.2 ENG OUT" w/ Master Warning

Question 28

What is considered a hot start?

Answer 28

> 900 degrees C w/ Ng below 60% and Np below 50%

Question 29

What function allows engines to operate at a higher TGT?

Answer 29

Contingency Power

Question 30

What is lost with Contingency Power?

Answer 30

ECS (bleed air is retained to increase TGT)

Question 31

What factors cause the EDECU to initiate auto-contingency power?

Answer 31

1.) Np less than 96% 2.) Greater than 3% droop b/w Np speed and Np Ref speed 3.) Greater than 5%/second Np droop rate when actual Np is less than or equal to Np Ref speed

Question 32

Will there be a notification when the EDECU initiates auto-contingency power?

Answer 32

No

Question 33

During start, at ___% Ng, the variable guide vanes closes the anti-ice/start bleed valve.

Answer 33

90% Ng

Question 34

IDLE Ng %

Answer 34

52-65% Ng

Question 35

FLY Ng %

Answer 35

96-101% Ng

Question 36

The engines are governed to maintain a Tq match under ___%.

Answer 36

Within 5% Tq of each engine

Question 37

Prior to a cross-bleed start, the donor engine must be operating at a minimum of ___% Ng

Answer 37

90% Ng

Question 38

"ENG OUT" and Red X displayed if Ng drops below ___%

Answer 38

Below 55% Ng

Question 39

There are two Np sensors in the exhaust from. What specifically do the left and right sensors provide?

Answer 39

Left: Np governing and Tach signal to EDECU Right: Tq computation circuit and Np overspeed protection