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Boeing 757/767 > Engines/APU > Flashcards

Engines/APU Flashcards

1
Q

Thrust Reference Modes

A

Takeoff:

  • TO
  • TO 1
  • TO 2
  • D-TO
  • D-TO 1
  • D-TO 2

Climb:

  • CLB
  • CLB 1
  • CLB 2

Continuous:

  • CON
  • CON 1
  • CON 2

Cruise:

  • CRZ
  • CRZ 1
  • CRZ 2

Other:

  • GA
  • MAN
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2
Q

EGT Start Limit Line

A

Displayed (Red) prior to and during engine start until engine is stabilized

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3
Q

When is the Inflight start envelope displayed

A
  • respective Fire Switch in
  • Fuel Control switch is in CUT OFF
  • N2 RPM(N3-RR) is below idle
  • Primary and Secondary EICAS displayed
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4
Q

Secondary EICAS engine indications

A
  • N2 RPM
  • Fuel flow (FF)
  • Oil pressure
  • Oil temperature
  • Oil quantity
  • Vibration
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5
Q

Engine vibration indication sources

A

N1
N2
BB - source is unknown and average vibration is displayed

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6
Q

When does the Standby Engine Indicator (SEI) in view?

A

In AUTO:

  • AC Power is lost
  • EICAS display failed

Selected ON

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7
Q

Engine Start Valve light illuminated (amber)

A
  • start valve not in commanded position

- N2 RPM exceeds 50% and starter valve open

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8
Q

Engine Start Selector positions

A

GND

  • Opens Start Valve
  • arms selected ignitors
  • selector magnetically held in GND position until 50% N2

AUTO

  • closes start valve
  • terminates ignition
  • selected ignitors operate continuously when slats extended or engine Anti-ice ON

OFF
- no ignition

CON
- selected ignitors operate continuously (no time limit)

FLT
- Both ignitors operate continuously (no time limit) regardless of selector position

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9
Q

EEC Power Switch

A

NORM - Aircraft power provided to EEC when engine is not running

ALTN - Permanent magnet alternator (PMA) selected to provide power to EEC when engine is running

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10
Q

APU Fault Light

A
  • APU has automatically shutdown

* APU fuel valve disagrees with the commanded position

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11
Q

APU Selector in the OFF position

A
  • Closes APU bleed air valve, if open
  • Initiates APU cooling cycle
  • Closes the APU fuel valve and inlet door shutting down APU when cooling cycle is complete
  • Resets auto shutdown fault logic
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12
Q

Engine description (PW)

A
  • 2 x Pratt and Whitney PW2037
  • 37,000 lbs of takeoff thrust
  • two-rotor axial flow turbofans of high compression and bypass ratio
  • N1 Rotor —> Fan, low pressure compressor, low pressure turbine
  • N2 Rotor —> high pressure compressor, high pressure turbine
  • N2 Rotor drive accessory gear box
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13
Q

Primary Engine Indications (PW)

A
  • EPR
  • N1
  • EGT
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14
Q

What determines max EPR value?

A
  • Electric Engine Control (EEC), or
  • Thrust management computer (TMC)

*EPR varies with existing ambient conditions

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15
Q

Reduced takeoff trust ratings

A

TO 1 - approx 91% of takeoff thrust

TO 2 - approx 81% of takeoff thrust

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16
Q

How is Assumed Temperature Takeoff thrust calculated

A
  • Thrust Management Computer (TMC) calculated the reference EPR(N1 - 767)
  • temp entered via TMSP or CDU TO Ref page
  • limited to 25% reduction of takeoff thrust or selected climb thrust
17
Q

Reduced Climb Thrust rating

A

CLB 1 - approx 92% of max climb thrust

CLB 2 - approx 85% of max climb thrust (noise abatement reduced thrust level)

18
Q

Purpose of EECs

A
  • electronic engine control
  • dual channel (primary and secondary)
  • set thrust by controlling EPR based on thrust lever position
  • powered by respective engine PMA when engine is running
19
Q

When does EEC switch from Primary to Secondary Control mode?

A
  • Primary can set thrust using EPR, N1, or N2 control mode
  • Secondary can only use N1 or N2 control mode
  • automatic switching occurs when primary mode becomes incapable of maintaining control
  • automatic switching also occurs when engine shutdown inflight
20
Q

How can you determine EEC has switched from EPR to N1 control mode

A
  • EPR display blanks

- small thrust increase

21
Q

N2 Control Mode

A
  • EEC operation in EPR or N1 not possible
  • ENG LIM PROT illuminates
  • automatic thrust limit protection is not available
  • inflight idle speed between both engines may be different
  • EGT and rotor speeds must be monitor during reverse thrust operation
22
Q

L or R ENG STATOR EICAS message

A
  • both channels of EEC are unable to control stator vane actuator
  • if engine fails and messages remain displayed engine restart is not possible
23
Q

Engine Overspeed Protection

A
  • EEC provides N1 and N2 red line Overspeed protection
  • If N1 or N2 approaches overspeed, EEC commands reduced fuel flow
  • no EGT overtemp protection
24
Q

Engine Start Sequence (PW)

A
  • ENG START selector to GND:
    • opens start valve
    • engages air driven starter (connected to N2 rotor)
    • closes engine bleed valve
  • FUEL CONTROL switch to RUN as N2 accelerated to Maximum motoring speed (less than 1% in 5 sec)
    • opens spar and engine fuel valves
    • activate selected ignition (normally one ignitors for grnd start and two for inflight starts)
  • at approx 50% N2
    • ENG START selector moves to AUTO
    • starter cuts out and start valve closes
    • engine bleed valve opens
25
Q

Starter Normal Duty Cycle and Re-engagement speed

A
  • 3 attempts of up to 2 mins each followed by cool down to 0% N2
  • 15 min cool down after 3 attempts

Re-engagement speed:

0% N2 - recommended
0-20% N2 - normal

26
Q

Power source for Ignition

A

Primary - Main AC power

Backup - STBY AC power

27
Q

How is fuel routed from tank to engine?

A
  • Fuel supplied by pumps located in fuel tanks

Spar Valve (located in main tank) —> 1st stage engine fuel pump (pressure added) —> fuel/oil heat exchanger (preheated) —> fuel filter —> 2nd stage engine fuel pump (pressure added) —> fuel control unit (control by EEC for fuel metering) —> engine fuel valve —> engine

28
Q

Where are Oil Temp and Oil Pressure measured?

A
  • Oil pressure is measure prior to entering the engine

- Oil temp is measure after leaving the engine

29
Q

Moving reverse thrust levers to interlock position

A
  • autothrottle disengages

- auto Speedbrakes deploy

30
Q

What happens when reverser system is activated

A
  • reverser isolation valve opens allowing reverser sleeves to hydraulically move aft
  • fan flow blocker doors rotate to direct fan air through stationary cascade guide vanes
  • REV display above EPR (amber during transition; green when fully deployed)
31
Q

APU operating envelope

A
  • electrical power has priority over bleed
  • electrical power is avail through entire aircraft envelope
  • bleed avail to approx 17,000’
32
Q

Compressor/Turbine stages PW-2037 (757)

A
  • 1 stage Fan
  • 4 stage LP compressor
  • 12 stage HP compressor
  • 2 stage HP Turbine
  • 5 stage LP Turbine
33
Q

Compressor/Turbine stages RR-RB211 (757)

A
  • 1 stage fan
  • 7 stage IP compressor
  • 6 stage HP compressor
  • 1 stage HP turbine
  • 1 stage IP turbine
  • 3 stage LP turbine
34
Q

Compressor/turbine stages CF6-80C2 (767)

A
  • 1 stage fan
  • 4 stage LP compressor
  • 14 stage HP compressor
  • 2 stage HP turbine
  • 5 stage LP turbine
35
Q

APU Control Switch ON

A

ON (APU operating position) -

  • Opens APU fuel valve and inlet door
  • Activates AC or DC fuel pump
  • Powers the APU controller
  • Permits the APU bleed valve to open if the APU Bleed switch is on when APU reaches
    operating speed
36
Q

How many batteries are required for APU start?

A

2 - APU Battery and Main Battery

– APU battery powers inlet door, starter and start circuitry
– Aircraft battery powers DC fuel pump, fuel valve, and fire detection

37
Q

What signals that the APU self test has been conducted?

A

The APU RUN light will illuminate twice during start

38
Q

Maximum thrust reduction allowed by Thrust Management Computer (TMC)

A

25% of Takeoff Thrust or Selected Climb Thrust, whichever is the greater thrust value

39
Q

What lights illuminate during APU Start Sequence

A 
• During APU start sequence, the following lights illuminate:
   o FAULT (once) as APU fuel valve opens
   o RUN (twice) as self-tests occur

Boeing 757/767 (19 decks)

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