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B777 CATHAY STUDY GUIDE > POWERPLANT > Flashcards

POWERPLANT Flashcards

1
Q

What are the primary engine parameters on the 300-ER?

A

N1 and EGT

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2
Q

What are the secondary Engine parameters on the 300-ER?

A

N2, fuel flow, oil pressure, oil temperature and Engine vibration

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3
Q

When are EGT indications inhibited from changing to Amber?

A

For 5 min during take-off or go-around

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4
Q

How can the red exceedance box be removed from EICAS?

A

By pressing the CANC/RECALL switch on the display select panel

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5
Q

Which two engine parameters change to black (reverse colours) when abnormal?

A

Oil quantity and ENG VIB

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6
Q

How can maximum rated thrust be obtained?

A

In normal mode: by´moving the thrust levers to the full forward positions

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7
Q

What are the two levels of control is available in EEC alternate mode and what is the difference?

A
  • Soft Alternate Mode:
    If these numbers are not valid, the EEC changes to the SOFT ALTERNATE mode. The EEC now calculates the required thrust N1 by estimating the Mach number looking at the total air temperature (TAT), standard day temperature (from P0) and the last valid difference between the standard day temperature and static temperature (TO). As the EEC estimates the Mach number, lower thrust N1 can be the result but also a possible engine limit exceedance may occur when the OAT changes during the SOFT ALTERNATE mode operation.
  • Hard Alternate Mode:
    To calculate thrust N1 the EEC uses now static pressure (P0) to assume the Mach number together with an assumed OAT for the highest thrust N1 setting requirement. This makes sure that the required aircraft performance is met, but can cause thrust exceedances resulting in excessive EGT’s. A good reference is the FMC computed green marker on the N1 indicator to prevent over-boosting the
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8
Q

How is engine EEC soft mode selected?

A

When the EEC automatically switches to the alternate mode but the EEC mode switch remains in NORM

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9
Q

How is hard engine alternate mode selected?

A

Manually. By pushing the EEC mode switch to ALTN

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10
Q

In which EEC modes is A/T available?

A

In Normal Mode and Alternate Modes

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11
Q

When is maximum rated thrust achieved in Alternate Mode?

A

Before the full forward position of the thrust levers

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12
Q

What protections are available in EEC
alternate mode?

A

N1 and N2 red line protections

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13
Q

How does the EEC protect against N1 or N2 overspeed?

A

By commanding reduced fuel flow

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14
Q

Why is approach idle selected with FLAPS 25?

A

To decrease acceleration time for a go-around

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15
Q

During autostart, what do the fuel control switches do?

A

They open the spar valve and arm the Engine fuel valve and ignitiors.
The EEC will open the Engine fuel valve and start the ignitors when the appropriate N2 and N3 RPMs are reached

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16
Q

When does the EGT maximum start limit disappear?

A

Once the engine is stabilized at idle

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17
Q

Which fuel valve is operated by moving the fuel control switch to RUN?

A

The spar valve in autostart.
The spar valve and engine valve in manual start

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18
Q

Does autostart monitor all engine parameters?

A

No, not oil temperature

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19
Q

After an aborted ground start, at what EGT will a re-attempt be performed?

A

After the EGT falls below 100 deg C

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20
Q

How many times will autostart re-attempt a ground start?

A

Twice for a hot start, no EGT rise or compressor stall
For more serious abnormalities (no N1 rotation) it will not make a second attempt

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21
Q

For which events will autostart not attempt to re-start for a ground start?

A

No N1 rotaion
Low air starter pressure
Starter shaft failiure
Duty cycle timer expires
Start is aborted above starter cut out speed
Oil pressure less than 10 psi

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22
Q

After an aborted in-flight start, at what EGT will a re-attempt be performed?

A

200 deg C or lower

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23
Q

During a manual start, when are fuel and ignition introduced?

A

As soon as the fuel control switch is positioned to RUN

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24
Q

In flight, how many attempts will the autostart perform?

A

The autostart will make continous start attempts until the engine either starts or the pilot aborts the start attempt

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25
Q

How many igniters are used for in-flight starting?

A

Dual ignitors are always used for in flight starts

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26
Q

How is flameout protection for the engines accomplished?

A

By both igniters activating

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27
Q

When is the auto ignition function activated?

A

Whenever an engine is at or below idle with the fuel control switch in RUN

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28
Q

What are the lower limit for engine oil quantity?

A

There is no minimum oil quantity limit

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29
Q

How are the fan reversers activated?

A

Hydraulically

30
Q

When can maximum reverse thrust be achieved?

A

When the interlock releases

31
Q

What is the purpose of the reverse thrust interlock?

A

A/T disengages and auto speed brake deploy.
When released, maximum reverse thrust can be achieved

32
Q

Where is average vibration indicated?

A

On the secondary engine display

33
Q

What is the limitaion for engine vibration?

A

There is no limit, but high vibration level will cause automatic display of secondary engine parameters (4 units)

34
Q

Which rotor vibration is mostly likely to cause tactile vibration?

A

N1

35
Q

When will the ENGINE FAIL message appear on the PFD?

A

If actual thrust is less than commanded thrust during take-off with airspeed between 65 kts and V1 -6 kts

36
Q

Which EICAS message indicates that actual thrust is significantly less than the commanded thrust?

A

ENG THRUST L/R

37
Q

What is the name and model designator for the B777-300ER engine?

A

GE90-115B/L2

38
Q

What does the L2 designator in the GE engine mean?

A

The L2 means that the Electronic Engine Control (EEC) control software gives a T/O bump. This feature can be used at airports between 4’000-9’500 ft at temperatures ranging from +14°C to +32°C to give a thrust increase of 1,1% - 2,5%.

39
Q

Will T/O bump thrust kick in if it is not pre-selected?

A

The EEC will allow T/O bump thrust even if it isn’t selected when the thrust levers are advanced manually to max thrust.

40
Q

How much of the air through the GE engine is bypass air and how much goes through the core?

A

83% of the thrust is generated from the bypass air and 17% comes from the air going through the core of the engine.

41
Q

What is the rated thrust (lbs) for the GE90 engine?

A

115’540 lbs

42
Q

What is the max continous thrust rating (lbs) for the GE90 engine?

A

110’000 lbs

43
Q

What parts does the N1 rotor system consist of?

A

The N1 low pressure compressor rotor consists of a fan (1 stage), a low pressure compressor section (4 stages) and a low pressure turbine (6 stages) on a common shaft.

44
Q

What parts does the N2 rotor system consist of?

A

The N2 high pressure compressor rotor consists of a high pressure compressor (9 stages) and a high pressure turbine section (2 stages) on a common shaft

45
Q

Which rotor system drives the accessory gear box?

A

The N2 rotor drives the engine accessory gearbox.

46
Q

What is the N1 limitations in rpm and %?

A

N1 = 110,5 % which equals 2602 rpm. 100% N1 is 2355 rpm

47
Q

What is the N2 limitations in rpm and %?

A

N2 = 121,0 % which equals 11’292 rpm. 100% N2 is 9332 rpm

48
Q

What is the different EGT temperature limitations?

A

EGT = 750°C (ground start), 825°C (air start), 1’050°C (all altitudes, no limit), 1’090°C (all altitudes, 5 min) and 1’095°C (below 17’000 ft, 30 seconds)

49
Q

What are the oil temperature limitations?

A

Oil temp = 132°C (no limit), 143°C (15 min)

50
Q

What are the oil pressure limitations?

A

Oil pressure = 10 psi (no limit), below 10 psi (15 seconds)

51
Q

What is the meaning of the color lines on the N1 indicator?

Red line
Amber line
Green line
White line

A

-Red line is the maximum speed limit for the N1 rotor.
Red line is an overspeed

-Amber line is the highest N1 that will not cause the engine to exceed maximum rated thrust for the ambient conditions. The EEC calculates this maximum N1. If you advance the thrust levers full forward, this is the max N1 the EEC will allow.
Amber line is an overboost

-Green line is the best N1 for the selected thrust mode. The FMC supplies this nr.
Green Line turns Magenta when VNAV is engaged (target N1)

-White line is the actual N1

52
Q

Where is EGT measured?

A

EGT is measured at the LPT inlet.

53
Q

What is the meaning of the color lines on the EGT indicator?

Red line
Amber line
White line

A

Red line is the maximum EGT limit during takeoff (1090 with 1095 available). Amber line is the maximum continuous EGT (1050). White line is the actual EGT

54
Q

What is EEC Normal Mode?

A

When operated in the normal mode the EEC modulates the fuel flow so as to control the N1 based on inputs from the thrust levers

55
Q

What is EEC alternate Mode?

A

The alternate mode schedule provides equal or greater thrust than the normal mode for the same thrust lever position. In alternate mode with the thrust levers at a specific position, the trust changes as the flight conditions changes

56
Q

Describe what happens in the fuel and engine systems during an AUTO start

A

Moving the FUEL CONTROL switch to RUN opens the spar fuel valve, but not the engine fuel shut off valve. With the FUEL CONTROL switch in RUN, the EEC is activated and opens the engine fuel SOV and energizes the ignitors at the appropriate N2 rpm. The normal supply of power to the ignitors are 115 VAC from the L or R MAIN AC BUS with the STANDBY BUS as the back-up source.

During an auto start, the EEC starts a 15 second timer when the N2 gets to 2’000 rpm (21,4%). After 15 seconds, the ignition system starts and at 18 seconds the fuel metering valve opens. The EEC removes power to the igniter(s) at 56% N2 and the START selector pops back to NORM and goes into auto ignition mode.

57
Q

How many ignitors are used during an auto start?

A

1

58
Q

Describe what the EEC does if an engine fails to start and how many start attemps it will do?

A

If the engine does not start, the EEC closes the FMV and dry motors the engine for 4 seconds to purge unburnt fuel from the combustor. The EEC then selects both ignition systems and and makes a second and a third attempt. Before the third attempt the fuel flow is adjusted. If all three attempts fails, the EEC aborts the start. Fuel and ignition are shut off and the engine is motored for 30 seconds to clear any residual fuel. The starter air valve also closes and the START selector releases back to the NORM position. The EICAS message “ENG AUTOSTART L/R” will appear.

59
Q

How is the ignition system selected to auto ignition mode?

A

When the START switch goes back to NORM it enters an auto ignition mode.

60
Q

What events will activate auto ignition?

A
  • PS3 (compressor discharge air) air less than 175 psi
  • Rejected takeoff (RTO)
  • Engine flame out or rapid deceleration based on N2 rate exceeding a threshold for 240 msec
61
Q

What are the functions of the engine oil system?

A

Functions of the engine oil system:
- Supplies oil to lubricate, cool, and clean engine bearings and gearboxes
- Supplies oil to decrease vibration at the engine bearings (oil damping)
- Gives heat to the engine fuel to prevent ice formation in the fuel

62
Q

What is the volume capacity of the oil reservoir?

A

28 qts

63
Q

When is oil servicing required?

A

Oil servicing is necessary if the next flight is more than 6 hours.
If the flight is less than 6 hours, check the EICAS oil quantity display and service if quantity is less than 18 qts

64
Q

At what oil quantity will you get a LO indication?

A

4 qts

65
Q

Is there a minimum required oil quantity for flight?

A

No

66
Q

Describe how the oil system works and how oil is circulated through the system?

A

Oil is pressurized by an engine-driven oil pump. From the pump, the oil flows through an oil filter that has a by-pass line in case the filter gets clogged. In such case the EICAS “ENG OIL FILTER L/R” appears. Oil then flows through the oil/fuel heat exchangers and then through the backup generator oil/oil heat exchanger for final delivery to the engine main bearings, gears and accessory drives. A scavenge pump returns the oil to the oil tank.

67
Q

What is the purpose of the Interlock stop for the thrust reverse system?

A

The purpose of the interlock stop is to prevent full reverse thrust until the 2 thrust reverser sleeves have deployed to about 60%.

68
Q

How are the thrust reversers actuated?

A

Hydraulically

69
Q

Describe what happens in the reverser system when full reverse thrust is selected

A

When the thrust reverser sleeve moves to the aft position by hydraulic actuators, the blocker door drag links move the blocker doors into the fan duct to re-direct the airflow. The air is directed though the vanes of the cascade segments which turns the air out to the side of the thrust reverser in a forward direction. This produces reverse thrust.

70
Q

When should the fuel control switch be selected to run during a “Manual Start”?

A

When N2 reaches maximum motoring speed. Which is defined as less than 1% gain in speed in 5 seconds

71
Q

Which two things happens when the reverse thrust lever is raised to the “Idle reverse thrust” position?

A

Auto throttle disengages
Speed brakes deployed, even if they were not armed

72
Q

What two things happens when the reverse thrust lever is moved to the “Reverse Idle” position?

A
  1. Auto throttle disengages
  2. Speed brakes deploy, even if they were not armed

B777 CATHAY STUDY GUIDE (24 decks)

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