Powerplant (Non Oral Exam Guide)

Question 1

What type of engine do we have

Answer 1

CFM-56: high-bypass ratio, twin spool, axial flow turbofan

Question 2

How many igniters

Answer 2

A and B

Question 3

What components are part of the engine gear box?

Answer 3

• lubrication unit, including the engine oil pumps
• engine fuel pumps and FCU
• FADEC
• IDG
• engine starter
• engine hydraulic pump

Question 4

What is FADEC?

Answer 4

Full Authority Digital Engine Control: computer that interfaces with numerous aircraft systems to control engine operation and performance

Question 5

What types of functions does the FADEC perform?

Answer 5

• control of gas generation
• protection against engine exceeding limitations
• power management
• automatic and manual engine starting sequencing
• thrust reverser control
• fuel recirculation control
• detection, isolation, and recording of failures

Question 6

How is the FADEC powered?

Answer 6

An internal magnetic alternator

Question 7

In the event the FADEC’s alternator fails, what happens?

Answer 7

The FADEC will revert to aircraft electrical power

Question 8

When is FADEC self-powered?

Answer 8

When N2 is above 12%

Question 9

How can we tell if the FADEC is not powered?

Answer 9

Engine indications are replaced with amber X’s

*also appear 5 mins after engine shutdown

Question 10

What redundancy does the FADEC have?

Answer 10

• Dual channel redundancy- one channel is active while the other is standby
• If one channel fails, the other automatically takes control

Question 11

Regarding fuel, what does moving the ENG MASTER switch to off do?

Answer 11

• Commands the closing of the LP and HP fuel shut off valves for that engine’s fuel system
• closes the fuel return valve and opens the bypass valve

Question 12

During an automatic engine start, what controls the HP Fuel Shutoff Valve?

Answer 12

FADEC

Question 13

What igniter must be operational for all flights? Why?

Answer 13

Igniter A- only igniter powered when in the Emergency Electrical Configuration mode

Question 14

When will FADEC activate and terminate ignition?

Answer 14

Activate when N2 reaches 16% and terminates when N2 reaches 50%

Question 15

What conditions will FADEC automatically activate continuous ignition?

Answer 15

• when a delayed engine start is sensed
• when the Engine Interface Unit (EIU) fails
• when an engine flameout is detected

Question 16

What is different for the igniters during a manual engine start?

Answer 16

FADEC activates both igniters when the Engine Master switch is placed ON. Ignition stopped when N2 reaches 50%

Question 17

What is the Thrust Lever Angle (TLA)?

Answer 17

Thrust rating limit and N1 for given position of thrust levers

Question 18

What are the 3 different idle modes?

Answer 18

• Modulated Idle
• Approach Idle
• Reverse Idle

Question 19

What is Modulated Idle?

Answer 19

Regulates thrust according to bleed system demands and ambient temps

• In flight: when the flaps are retracted
• On the ground: when reverse is not selected

Question 20

What is Approach Idle?

Answer 20

Engages in flight when flaps are extended. Idle is regulated according to altitude and is not dependent on bleed system demand

Question 21

What is Reverse Idle?

Answer 21

Engages on the ground and the thrust lever is in the Reverse Idle position. Reverse Idle is slightly higher than forward idle thrust

Question 22

When does FADEC command a higher engine idle speed?

Answer 22

• bleed demands
• high engine or IDG temps
• Approach configuration

Question 23

During start, FADEC controls monitoring and sequencing of:

Answer 23

• start valve opening and closing
• ignition activation and termination
• fuel valve opening
• N1, N2, and EGT exceedance protection

Question 24

What is the manual start sequence?

Answer 24

1. ENG MODE selector: Ignition/Start
2. Engine Manual Start pushbutton: ON (engages starter and windmills engine)
3. When max motoring speed reached: ENG Master switch: ON (activates ignition for both igniters and opens LP and HP fuel valves)

Question 25

Does FADEC have abort authority during a manual start?

Answer 25

No, only passively monitors the start and displays sensed abnormalities on the E/WD

Question 26

Compared to an automatic start, what protections are not provided with a manual start?

Answer 26

- will not provide EGT exceedance protection (unless EGT limit is exceeded prior to 50% N2, then FADEC aborts the start) * still provides N1 and N2 exceedance protection

Question 27

Does FADEC have abort authority during an inflight relight?

Answer 27

No

Question 28

When does the automatic relight logic activate?

Answer 28

When FADEC senses that engine’s N2 RPM has decreased below a pre-set limit

Question 29

What does a fault light on the ENG panel indicate?

Answer 29

- auto start abort - position of FUEL HP shutoff valve abnormal - malfunction of the thrust control

Question 30

What determines the max thrust the A/THR system will be able to command?

Answer 30

The position detent of the thrust lever

Question 31

During a normal automatic start sequence; what does moving the ENG Master switch to ON do?

Answer 31

- LP fuel valve opens - start valve opens - APU speed increases - ignition starts: when N2>16% - N2>50%: start valve closes, igniter off (if on ground), APU speed returns to norm, pack valve reopens after 30 secs

Question 32

What does pushing the ENG FIRE pushbutton do?

Answer 32

- silences aural fire warning - arms fire extinguisher squibs - closes the low-pressure fuel valve - closes the hydraulic fire shut off valve - closes the engine bleed valve - closes the pack flow control valve - cuts off FADEC supply power - deactivates the IDG

Question 33

What occurs when the engine fire TEST button is pressed?

Answer 33

- continuous repetitive chime sounds (CRC) - MASTER WARN lights flash - ENG FIRE on the ECAM - ENG FIRE pushbutton illuminates in red - SQUIB and DISC light illuminate - FIRE lights on ENG panel on pedestal

Question 34

When will FADEC abort a start?

Answer 34

- stalled start - no light up - hot start, hung start