Engines Flashcards

1
Q

Describe the engines

A
  • Two CFM56-7, dual rotor, axial-flow turbofan.
  • N1 rotor consists of a fa, a low pressure compressor and a low pressure turbine
  • N2 rotor consists of a high pressure compressor and a high pressure turbine
  • N1 and N2 are mechanically independent
  • A bleed air powered starter motor is connected to the N2 rotor
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2
Q

What regulates each engine ?

A

Dual-channel EEC

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3
Q

What are primary engine indications ?

A

N1 and EGT

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4
Q

What are secondary engine indications and when do they display ?

A

N2, fuel flow, oil pressure, oil temp, oil quantity and engine vibration.

automatically displayed when:

  • the displays initially receive electrical power
  • in flight when a engine start level is moved to cutoff
  • in flight when the engine N2 RPM is below idle
  • a secondary engine parameter is exceeded
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5
Q

How does the EEC in normal mode calculate N1 setting?

A

sensed flight conditions and bleed air demand to calculate N1 thrust setting

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6
Q

How many EEC alternate modes?

A

2: Hard and Soft

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7
Q

EEC’s have how many different types of idle?

A

Ground minimum idle (for ground operations),

flight minimum idle (most phases of flight)

approach minimum idle (if flaps are in landing config or engine anti ice is on)

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8
Q

How is fuel heated?

A

two fuel / oil heat exchangers where IDG oil and main engine oil heat the fuel

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9
Q

How does fuel get to the engine?

A

Fuel Spar Shutoff valve > first stage engine fuel pump > two fuel / oil heat exchangers > fuel filter > second stage fuel pump > hydro mechanical unit (HMU) > Engine fuel shutoff valve

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10
Q

How is the oil system pressurized?

A

Engine driven oil pump

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11
Q

How is oil returned to the oil tank?

A

Scavenge pumps > scavenge filter > main engine oil cooler = oil tank

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12
Q

Engine start system requires what?

A

Pressurized air and electrical power

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13
Q

In the GRD position what does the engine use to close the engine bleed air valve and open the start value for pressure to rotate the motor?

A

Battery power

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14
Q

What is the recommend N2 value for engine start?

A

25%

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15
Q

What does the EEC detect during a ground start?

A

Hot starts, engine stalls, EGT start limit exceedances and wet starts

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16
Q

How many ignitors does each engine have ?

A

2: the left and right ignitors are powered by their respective AC transfer bus

17
Q

What is Auto-relight capability?

A

whenever the EEC detects an engine flameout both ignitors are activated. a flameout is detected by when an uncommanded rapid decrease in N2 occurs or N2 is below idle RPM

18
Q

What are the two methods of inflight starting ?

A

Windmill and crossbleed. None on the ground start protections are available in flight

19
Q

Thrust reverser’s are (blank) operated ?

A

hydraulically operated

20
Q

What system does the hydraulic power for thrust reverse come from

A

A and B respective from each side. If either A or B fails the standby hydraulic provides operation for the respective side (slower deployment).

21
Q

What keeps the reverses stowed during an uncommanded movement?

A

The auto-restow circuit opens the isolation value and commands the control valve to the stow position directing hydraulic pressure to stow the reverser.

22
Q

Engine starter cutout speed (400) and (800)

A

(400) = 46% N2

(800) = 56% N2