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777 > Engines and APU > Flashcards

Engines and APU Flashcards

1
Q

What are the primary engines indicators?

A

N1 and EGT

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2
Q

What are the secondary engine indications?

A

N2, fuel flow, oil pressure, oil temperature, oil quantity, and engine vibration

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3
Q

What does the EEC do?

A

Electronic Engine Control (EEC) monitors autothrottle and flight crew inputs through the thrust levers to control the engines.

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4
Q

Describe EEC normal mode.

A

Sets thrust by controlling N1 based on thrust lever position

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5
Q

Describe EEC alternate mode.

Soft vs Hard

A

In the alternate mode, the EEC schedules N1 as a function of thrust lever position.

Soft mode - switch normal and EEC mode is alternate
Hard mode - the switch position is ALTN, the EEC mode is alternate

Thrust protection is not provided in the alternate mode and maximum rated thrust is reached at a thrust lever position less than full forward.

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6
Q

How does overspeed protection work?

A

If N1 or N2 approaches overspeed, the EEC commands reduced fuel flow.

EICAS advisory message ENG RPM LIMITED (L or R) is provided

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7
Q

Describe the flow of oil to the engine

A
  • Oil is pressurized by an engine–driven oil pump.
  • From the pump, the oil flows through the oil filter. If the oil filter becomes clogged, then oil bypasses the oil filter and the EICAS advisory message ENG OIL FILTER (L, R) is displayed.
  • Then oil flows through the fuel/oil heat exchangers and
  • Then through the backup generator oil/oil heat exchanger
  • Then flows to the engine main bearings, gears, and accessory drives.
  • A scavenge pump returns the oil to the reservoir.
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8
Q

What is the minimum oil quantity and limitations?

A

No minimum oil quantity or limitations

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9
Q

What is the purpose of the airborne vibration monitoring system?

A

Primarily intended for engine condition monitoring, but it is also a useful tool for isolating and determining corrective action for engine anomalies.

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10
Q

APU bleed air is available at what altitudes?

A

At or Below 22,000’

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11
Q

Explain the APU start system.

What is the starter motor duty cycle?

A

Has an air turbine and electrical starter.

Air turbine starter has priority.

Gets fuel from the left manifold from the AC pump when AC power is available. From the DC pump when AC power isn’t available.

3 starts is a 60 min period for each motor.

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12
Q

What are the 2 modes of the APU?

Explain them

A

Attended and unattended.

Attended when either engine is running or starting and in flight.

Unattended all other times on the ground

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13
Q

When will the APU automatically start?

A

In flight, if both AC transfer busses lose power, the APU automatically starts, regardless of APU selector position.

The APU can be shut down by positioning the selector to ON, then OFF.

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14
Q

What causes the APU to shutdown automatically in the attended mode?

A
  • APU fire/inlet over temperature
  • overspeed/loss of overspeed protection
  • APU controller failure
  • speed droop.
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15
Q

What causes the APU to shutdown automatically in the unattended mode?

A
  • APU fire/inlet overtemperature
  • overspeed/loss of overspeed protection
  • high EGT
  • low oil pressure
  • high oil temperature
  • generator oil filter approaching bypass
  • intake door failure
  • APU controller failure
  • speed droop
  • no combustion on start
  • no acceleration on start.
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16
Q

What is the altitude limit for APU starting?

A

43,100’

17
Q

What protections do the EECs provide in the normal mode?

A
  • Thrust protection - Overspeed
  • During autostart the EEC controls fuel and ignition, and monitors EGT, N2 RPM, and other engine parameters
  • Selects min idle or approach idle
18
Q

What protections do the EECs provide in the alternate mode?

A

EECs provide N1 and N2 redline overspeed protection. If N1 or N2 approach overspeed, the EECs command reduced fuel flow

19
Q

What happens if the EECs detect an internal fault?

A

They automatically go into the soft alternate mode.

20
Q

Why do we select the hard alternate mode if the EEC has gone into the soft alternate mode?

A

To prevent thrust lever stagger at even thrust settings or to prevent asymmetrical thrust when thrust levers are not staggered.

Also to regain the command and reference prompts on the N1 indications with the autothrottle.

21
Q

What must we do before selecting the hard alternate mode? Why?

A

Retard the thrust levers to the mid position; to prevent overboost.

22
Q

Is the autothrottle available in the hard alternate mode?

A

Yes

23
Q

What should you know about thrust lever position and actual thrust between the normal and alternate modes?

A

The alternate mode schedule (N1 schedule) provides equal or greater thrust than the normal mode for the same thrust lever position.

24
Q

What is the difference between soft and hard alternate with respect to reference data?

A

Reference and target N1, and maximum and commanded N1 values are displayed on the N1 indication during the hard-alternate mode. Thrust may change to set the commanded N1 when ALTERNATE is manually selected with the autothrottle arm switch armed. In the soft alternate mode N1 reference/target values are computed by the FMC.

25
Q

How many start attempts will the autostart system make on the ground / in flight?

A

On the ground, 3 start attempts

For in–flight starts, auto start makes continuous start attempts

26
Q

When will autostart not attempt another start on the ground?

A

On the ground, autostart does not attempt a second or third start if there is no N1 rotation, insufficient air pressure, the starter shaft fails, the EGT exceeds the start limit line, or the start time exceeds the starter duty cycle. The EICAS caution message ENG AUTOSTART (L or R) is displayed.

27
Q

What does autostart NOT monitor?

A

Oil temp and pressure.

28
Q

What action should you take for no oil pressure during start?

A

Fuel control to cut off, call maintenance, do not motor the engine.

29
Q

When does the EEC select approach idle?

A

Approach idle is selected in flight when:
• engine anti–icing is operating
• the flaps are commanded to 25 or greater
• one hydraulic system air–driven demand pump is inoperative, and the
flaps are out of the UP position
• the opposite engine bleed air valve is closed

777 (23 decks)

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