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Lear 45 FS > Powerplant > Flashcards

Powerplant Flashcards

1
Q

What engines and how much thrust?

A

Honeywell TFE731-20

Each produces 3500lbs thrust static at SLP, and 3650lbs using APR

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2
Q

N1 Fan Gearbox output to input ratio

A

0.556

Fan spins at 0.556 of what the LP shaft spins at

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3
Q

Name the seven sections of the engine

A 
Air Inlet
Fan
Compressor
Combustor
Turbine
Exhaust
Accessory
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4
Q

Describe N1

A

Fan speed or low pressure rotor rpm.

Consists of the Fan, 4 stage LP compressor and 3 stage LP turbine.

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5
Q

Describe N2

A

Turbine speed or HP rotating group/spool.

Consists of single stage HP compressor and HP turbine.

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6
Q

How is ITT measured?

A

By 10 thermocouples located in between the HP and LP turbines.

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7
Q

What is the engine bypass ratio?

A

3.1 to 1

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8
Q

How many fuel nozzles per engine?

A

12 duples fuel atomizers & 2 ignitor plugs.

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9
Q

What drives the Accessory Gearbox?

A

The HP centrifugal compressor drives the tower shaft, which drives the transfer gearbox, which drives the accessory gearbox.

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10
Q

What is driven by the Accessory Gearbox?

A

(rear)
Oil pump
Engine driven Fuel pump
FCU

(front)
DC Starter/Gen
AC Alternator
Hyd pump
Motive flow fuel pump
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11
Q

What percentage is IDLE

A

Flight idle is 65%N2 and increases w altitude.

Ground idle is 52%N2.
It will be commanded 20secs after touchdown unless higher thrust is set.

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12
Q

What does DEEC provide?

A 
Thrust management
Rating display/N1 Bug
Overspeed protection
Automatic start sequence
Spool speed and temp limiting
Surge-free accel and dece
Engine synchronization
APR
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13
Q

FCU flyweight governer overspeed protection

A

Operates the fuel metering valve to restrict fuel flow to prevent the engine from exceeding 105%N2

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14
Q

DEEC overspeed protection

A

Closes overspeed solenoid valve at 107%N1 or 109%N2.

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15
Q

Describe the flow of fuel from wing to engine.

A

From wing to 2 stage LP and HP engine driven FP.

LP centrifugal FP to heater/cooler and filter and back thru the HP gear fuel pump.

From pump to FCU

FCU to fuel flow sensor

Sensor to flow divider

Divider to manifolds and nozzles.

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16
Q

Target N1 Bug settings should be within…

A

1% between both engines

17
Q

N1 Bug readouts

A

Ground/Flight w flaps or gear down: T/O power

Flight w gear/flaps up: detent power (APR,TO,MCT,MCR)

Below MCR the bug is removed.

18
Q

N2 range

A

0-115%

> 100% display is amber(101.1% for APR)

> 102.5% display is red

19
Q

Oil pressure range

A

65-80psig (white)

20
Q

Oil temp range

A

30-127°C

21
Q

What 3 scenarios does DEEC auto activate ignition?

A
  1. Normal engine start
  2. Uncommanded engine decel
    (N1 is set and N2 not accelerating)
  3. Excessive engine decel
    (to prevent flameout; actual decel is greater than decel commanded thru thrust levers)
22
Q

Describe DEEC normal ignition

A
  1. Thrust lever moved to IDLE
  2. START switch depressed

Ignition activated at 6.8%N2 and off at 45%N2

23
Q

Describe the colors of IGN

A
  1. Green: both ignitors on
  2. White: one not firing
  3. Amber: both not firing
24
Q

Describe the starting process

A

P. 7-26

Starter drives tower shaft which drives N2

DEEC commands ignition at 6.8%N2

Fuel introduced at positive N1 (~11-12%N2)

Ignition/Starter cutoff at 45%N2

DEEC brings generator online at 49.4%N2
(95% of ground idle/52%N2 is 49.4%)

Secondary signal for starter cutout at 50%N2

25
Q

Parameters of starting an engine

A

ITT indication within 10secs of initiation

Oil pressure within 10secs of lightoff

START turns amber if energized above 51%N2

Both spools should increase smoothly and rapidly after lightoff

60secs from start to idle N1

26
Q

Authority limits for SYNC

A

+/-5%N1 during midrange operation

0% at takeoff PLA

-2% to +5%N1 at flight idle

27
Q

When must SYNC be off?

A

Takeoff, landing, and single engine operations

Sync will not function during APR

28
Q

When will SYNC not be green?

A

Sync will be amber while the gear is not locked up. A chime will indicate an amber sync.

29
Q

What is APR?

A

APR provides automatic increase in thrust on the operative engine in the event of a power loss on the other during takeoff and missed approach.

The DEEC senses a > or =15% mismatch in N2 in auto mode. It can also be activated manually.

APR provides an extra 150lbs of thrust by increasing ITT limits by 22°C to allow a 2% increase in N2.

30
Q

How do you reset APR?

A

In auto, the APR ARM switch must be cycled off.

If accidentally activated on the ground by differential thrust, cycling the APR switch off and back to ARM with thrust N2 within 15% will reset the system.

31
Q

Engine oil capacity

A

8.6 quarts per engine

32
Q

Engine oil burn

A

1 quart per 25hrs

33
Q

When should oil levels be checked?

A

Within 1 hour after shutdown

34
Q

Oil pressure limits

A

50-100psi (up to 125psi for start)

35
Q

Reversers should be stowed at

A

40kias

Lear 45 FS (2 decks)

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