Powerplant

Table of Contents:-

Normal Operations:
  • Crossbleed Start
  • Starting In High Tailwinds
  • Engine Warm-Up and Cool Down (CF6-50E Engines)
  • Use of Fuel Heat

Alternate Operations - JT9D Engines:
TBA.

Alternate Operations - CF6-50E Engines:
  • Starting, Engine in Reverse
  • Engine(s) stuck in Reverse During Ground Operation
  • Manual Override Start
  • Aborted Start
  • Low Duct Pressure Start
  • No Indication of N1 Rotation
  • Start Valve Open Light Illuminated
  • Engine Over Temperature on the Ground Other Than Start
  • Engine Over Limits
  • High Oil Consumption
  • Low Oil Quantity Indication
  • Low or High Engine Oil Pressure
  • High Engine Oil Temperature
  • Oil Filter Bypass Light
  • Engine Stalls
  • Fuel Filter Bypass Light Illuminated
  • Ground Idle Light Illuminated in Flight
  • Engine Fuel Condition Actuator Light Disagrees With Start Lever Position
  • Tailpipe Fires
  • Thrust Lever Restriction


Controls and Indicators:
  • Pilot's Engine Indicating Instruments
  • Engine Controls
  • F/E Engine Indicating Instruments
  • TAT / EPRL Controls and Indications

Schematics:
  • JTD9D Engine
  • Oil System
  • Start & Ignition System
  • Engine Fuel System

Supplementary Information

Limitations




Normal Operations
Crossbleed Start:
If a crossbleed start is desired or required using an operating engine:
- Ensure area to rear of operating engine is clear
- Turn off all pneumatic bleeds not required, including air conditioning pack OFF
- Place ADP No. 4 in AUTO, then check brake pressure in green band
- Set the parking brakes
- Advance thrust lever of operating engine slowly until pneumatic pressure is approximately 40 psi (less 1 psi per 1000 feet of pressure altitude) and HIGH STAGE valve light remains illuminated.  70% (75-80% for CF6-50E) N2 is the normal power setting required to attain 40 psi duct pressure.
Note:  Power settings above 70% (84% for CF5-50E) N2 may cut out high stage bleed (HIGH STAGE valve light extinguishes) and reduce duct pressure below required minumum.
- Complete normal engine start procedure.

Starting In High Tailwinds:
JT9D Engines - Move the start lever to RICH (cold engine) or IDLE (warm engine) at maximum motoring speed.  A slightly higher EGT should be anticipated.
CF6-50E Engines - A slightly higher EGT should be anticipated and N1 may be slower in reaching idle if reversing rotation was experienced during the start cycle.

Engine Warm-Up and Cool Down (CF6-50E Engines):
A three minute warm-up/cool down period should normally be allowed at or near ground idle after start and prior to shutdown.  Taxi time may be included as part of the three minute period.

Use of Fuel Heat:
When manual fuel heat is used inflight, a maximum of two fuel heat switches should be positioned to ON at the same time.  Monitor engine instruments during fuel heat operation.
Fuel heat should be OFF for takeoff and landing and should be positioned to AUTO during climb, cruise and descent.  When fuel heat is applied, manually or automatically, check that engine fuel temperature increases and HEATER lights illuminate.  Engine fuel temperature indications may exceed 60 C.

In Flight (Using cyclic fuel heat switch):
If the outboard engine fuel temperatures reach -5 C or below and if desired:
1 and 4 Cyclic Ht Switch ..... ON
Check corresponding HEATER lights illuminate for one minute and every ten minutes thereafter.  Adjust thrust as necessary.

Alternate Operations - JT9D Engines
TBA.

Alternate Operations - CF6-50E Engines

Starting, Engine in Reverse
:
Starting with engine thrust reverser(s) in reverse position is permissable.
Reverst Thrust Levers ..... DOWN (Forward) POSITION
Forward Thrust Levers ..... IDLE POSITION
Observe normal start procedures.  When bleed pneumatic pressure increases, thrust reverser(s) should return to forward (stowed) position.


Engine(s) stuck in Reverse During Ground Operation
Manual Override Start
Aborted Start
Low Duct Pressure Start
No Indication of N1 Rotation
Start Valve Open Light Illuminated
Engine Over Temperature on the Ground Other Than Start
Engine Over Limits
High Oil Consumption
Low Oil Quantity Indication
Low or High Engine Oil Pressure
High Engine Oil Temperature
Oil Filter Bypass Light
Engine Stalls
Fuel Filter Bypass Light Illuminated
Ground Idle Light Illuminated in Flight
Engine Fuel Condition Actuator Light Disagrees With Start Lever Position
Tailpipe Fires
Thrust Lever Restriction


Controls and Indicators

Pilot's Engine Indicating Instruments:


Reverser Operating Light (Amber) - Illuminated:
- Reverser is not in full forward thrust position (stowed)
- Will also illuminate for a failure of a protection feature which prevents thrust reverser actuation in flight.

Reverser In Transit Light (Blue):
Illuminated - Reverser is in transit between forward and reverse thrust positions.
Light is extinguished with reverser in full reverse or full forward position (stowed).

N1 RPM Indicator:
Indicates percent of RPM of low pressure compressor.  Secondary thrust setting instrument.
Pointer and digital readout.  Maximum indication pointer indicates overspeed only and remains at highest  reading until reset.  With electrical power loss or instrument failure, warning flag drops in front of window.

Engine Pressure Ratio Indicator:
Indicates ratio of turbine discharge pressure to compressor inlet pressure.  Primary thrust setting instrument.  Pointers and digital (lower window) readout.  Indicator has two modes of operation:
Manual Mode - Knob out and M flag replaces left digit in upper window.  Bug and upper readout respond to rotation of knob.
Automatic Mode - Knob in M flag out of view.  Bug and upper digital readout respond to TAT/EPRL mode selector.
With electrical power loss a warning flag drops in front of lower digital readout.

Exhaust Gas Temperature Indicator:
Indicates temperature of exhaust gas between high and low pressure turbines.  Pointer and digital readout.  Amber light (on indicator face) illuminates to indicate that the EGT is approaching or has reached a critical over temperature condition.  Maximum indication pointer registers overheat condition and remains at highest reading until reset.  With electrical power loss or instrument failure, warning flag drops in front of window.

Fuel Flow Indicator:
Indicates metered fuel flow to engine.  Pointer and digital readout.  With electrical power loss or
instrument failure, warning flag drops in front of window.
Note:  The fuel flow indicator(s) may give an erroneous indication of fuel flow when electrical power is applied to the airplane with the engines shut down.


Engine Controls

Forward Thrust Lever:
Selects power.  Movement unrestricted except when reverse thrust levers are being used or fan reverser is not in forward. 

Engine Start Lever:
CUTOFF - Fuel and ignition off.
RICH - An enriched quantity of fuel available to engine and ignition available as selected.  Use to start a cold engine.  Move start lever to IDLE after EGT stabilizes.
IDLE - Fuel available to engine and ignition available as selected.  Use to start a warm engine.

Reverse Thrust Lever:
Selects power for reverse thrust.  Cannot be actuated unless forward thrust levers are in idle position.  Interlock prevents application of reverse thrust until fan reverser reaches full reverse position.


Ground Idle Light (Amber):
Illuminates on the ground if trailing edge flaps are at 25 or 30.
Note:  If illuminated in the air when trailing edge flaps are positioned to 25 or 30, one or more of the engines has remained in ground idle.


Engine Ignition:

GRD START - Momentary Position.  Either switch. SYS 1 or 2 will open start valve of selected engine.  When start lever is advanced to RICH or IDLE, and the corresponding engine ignition switch(es) SYS 1/2 are held in GRD START ignition will be supplied.  May be used for air start as defined by the inflight starting envelope to attain required N2 for starting windmilling engine.
OFF - Maintained position.  Ignition off, start valve closed.
FLT START - Maintained position.  With start lever in RICH or IDLE and the corresponding engine ignition switch(es) SYS 1/2 are positioned to FLT START ignition will be supplied.  Used to start windmilling engine and for takeoff, landing or adverse weather conditions.

Standby Ignition Switch:
Utilizes standby bus AC power to provide ignition from battery.
IGN 1 - Provides continuous ignition to all engines through ignitor No. 1 when start levers are in the RICH or IDLE position.
NORM - Off.
IGN 2 -
Provides continuous ignition to all engines through ignitor No. 2 when start levers are in the RICH or IDLE position.
Note:  Captain's heading information will be lost if the Standby Ignition Switch is positioned to IGN 1 or 2.



F/E Engine Indicating Instruments:


Engine Vibration Indicators:
Indicate continuous engine N1 vibration level.  Zero reading with engine operating indicates systems not functioning.

Engine Fuel Condition:
Illuminates bright in transit, in response to start lever movement from or to CUTOFF.  Remains illuminated bright if fuel conditioner valve is not in agreement with start lever position.  Light(s) extinguished when fuel conditioner valve is in agreement with start lever position in RICH or IDLE.  Light(s) illuminate dim when fuel conditioner valve is in agreement with start lever position in CUTOFF.


TAT / EPRL Controls and Indications:

Rating Select Switches:
When switch is depressed, upper portion of switch illuminates green.  "I" will provide -7 Dry performance for mode selected.  "II" will provide -3A Dry performance.  Push switch second time to cancel selection.  Repeater light on pilot's centre panel will also illuminate.

EPRL Mode Select Switch:
Selects phase of flight for EPR limit.  Will automatically position to GA when A/P or F/D is engaged and glide slope is captured or when flaps move to 25.
Note:  May position to GA when electrical power source is changed.

EPR Derate Display:
Displays derate increments of manual derate switch.

Manual EPR Derate Switch:
When switch is positioned to DECR the EPR Derate Display will indicate decrease in increments of .01 EPR up to a maximum of .10 EPR.
The decrease will also be indicated in the position of the bugs on the EPR indicator if the knob is in the automatic (in) mode.  INCR position will cancel previous input by .01 increments.
Displays "88" when master dim and test switch is placed in TEST position.

Test Switch:
When the switch is depressed the following values will appear in the TAT and EPRL windows of the digital indicator as the modes are selected:
TAT:     +1- Degrees (+/- .5)
EPRL:    (all values +/- .005)


Schematics
JTD9D Engine
Oil System
Start & Ignition System
Engine Fuel System

Supplementary Information

For airplanes equipped with Pratt and Whitney JT9D series engines, the takeoff thrust ratings at sea level for temperatures up to +80 F (+86F for -7J and -7R4G2) are as follows:  Dry / Wet

-7            45,500 / 47,000
-7A          46,150 / 47,650

-7F          46,750 / 48,650
-7J          50,000 / -
-7R4G2  53,500 / -

The engine is a forward fan, twin spool axial compressor type with a high bypass ratio (5 to1) which results in the fan delivering approximately 75% of the thrust.  The low pressure compressor unit (N1) consists of a single-stage fan and a three-stage (four stage for -7R4G2) compressor connected by a through shaft to a four-stage turbine.  The high pressure compressor unit (N2) consists of an eleven-stage compressor unit connected to a two-stage turbine through concentric shafting.  Variable stators, automatically positioned by fuel pressure, provide an adequate stall margin for engine starting, acceleration, and low power operation.  The fuel control unit schedules fuel to provide thrust called for by the thrust lever setting.

There are two engine idle speeds; low (ground) idle is used during ground operation and during all flight operations except approach and landing when the engines shift to high (flight) idle to facilitate engine acceleration for a go-around.  In flight, idle speed is determined by the position of trailing edge flaps.  Until flaps are positioned to 25 or 30, the engines remain in low idle.  High idle is then programmed and maintained until 5 seconds after touchdown.  Landing gear tilt sensors then dictate a shift to low idle.  The engine inlet is designed to provide optimum cruise performance.

The N2 compressor drives accessories through an angled gearbox.  A complete self-contained oil system provides lubrication and cooling of internal parts.  The thrust reverser system provides means of reversing fan exhaust air.

The engine starting system rotates the N2 compressor to establish airflow through the engine.  Air pressure to start engines is normally obtained from the APU, but can be supplied by ground equipment or an operating engine.  Dual, physically and electrically independant, 4 joule ignition systems are 115V AC powered.  A standby ignition system uses standby inverter AC power to provide ignition from the battery.  The nacelle inlets and first-stage stators have thermal anti-icing.

Engine bleed provides fuel heat when fuel icing is encountered or is anticipated.  Immediately after fuel heat is applied, EPR decreases approximately .01 due to increased engine bleed air usage.  The increase in temperature of fuel entering the fuel control unit causes metered fuel flow to rise.  Within about fifteen seconds, EPR increases approximately .03 with a corresponding rise in N1, N2 and EGT.  The EPR rise for -7R4G2 engines should not exceed the initial volume.

When use of fuel heat is terminated, EPR rises approximately .01 due to the decreased use of bleed air.  In approximately two minutes, as fuel temperature decreases, EPR, FF, N1, N2 and EGT return to the original pre-fuel heat usage setting.

Changes in engine parameters with use of fuel heat are normal.  Thrust lever position should be adjusted only when maximum EPR limits would be exceeded.

As installed:  A timer operated cyclic fuel heat system provides fuel heat for No. 1 & 4 engines.  By pressing the cyclic hear switch ON, the timer allows one minute of immediate fuel heat application, then ten minutes off and continues the one minute/ten minute cycle as long as the cyclic heat switch is left ON.

If a fuel icing condition occurs (ICING light illuminated) with number one and four engine fuel heat switches in AUTO position along with cyclic heat selected, fuel is applied and remains on as long as fuel icing exists.  When the fuel icing condition is eliminated (ICING light extinguished), the timer begins its ten minute off segment, then continues the one minute on/ten minute off sequence.

The cyclic fuel heat system, when activated, is independent and operates with the normal fuel heat switches in AUTO or OFF position.

A high pressure turbine case cooling system improves fuel consumption.  The system is automatically activated above 23,000 feet and cruise RPM.  Cool fan air is distributed around the N2 turbine case, thus reducing thermal expansion and maintaining a tighter seal between the case and the turbine blade tips.

The airborne vibration monitoring (AVM) system continuously indicates the vibration level of each engine.  Indicated AVM values vary between engines.  The installed vibration characteristics are unique to each engine, installation, and instrumentation.  The system is used for trend monitoring purposes.

Crew procedures associated with engine operation are based primarily on maintaining engine indications within operating limits.  There are no operating limitations for the AVM system; therefore, there are no flight crew actions (or procedures) based solely on a response to engine vibration indications.



For airplanes equipped with General Electric CF6-50 series engines, the takeoff thrust rating at sea level for temperatures up to +86 F / +30 C is 51,800 pounds.

The CF-6 is a dual rotor, axial flow, turbofan engine.  A high bypass ration results in the fan delivering approximately 75% of the thrust.  The low pressure compressor unit (N1) consists of a single stage fan and a three stage compressor connected to a four stage turbine.  The high pressure compressor unit (N2) consists of a fourteen stage compressor unit connected to a two stage turbine through concentric shafts.  The first six stages have variable stators positioned by the engine control in response to thrust lever movement.

There are two engine idle speeds; low (ground) idle is used during ground operation and during all flight operations except approach and landing when the engines shift to high (flight) idle to facilitate engine acceleration fo a go-around.  In flight, idle speed is determined by the position of trailing edge flaps.  Until flaps are positioned to 25 or 30, engines remain in low idle.   High idle is then programmed and maintained until 5 seconds after touchdown.  Landing gear tilt sensors then dictate a shift to low idle.  The engine inlet is designed to provide optimum cruise performance.

The N2 compressor drives accessories through an angled gearbox.  A complete self contained oil system provides for lubrication and cooling of internal parts.  The thrust reverser system provides means of reversing fan exhaust air.

The engine starting system rotates the N2 compressor to establish airflow through the engine.  Air pressure to start engines is normally obtained from the APU, but can be supplied by ground equipment or an operating engine.  Dual, physically and electrically independent, 15 joule ignition systems are 115V AC powered.  A standby ignition system uses standby inverter AC power to provide ignition from the battery.  The nacelle inlets have thermal anti-icing.

The airborne vibration monitoring (AVM) system continuously indicates the vibration level of each engine.  Indicated AVM values vary between engines.  The installed vibration characteristics are unique to each engine, installation, and instrumentation.  The system is used for trend monitoring purposes.

Crew procedures associated with engine operation are based primarily on maintaining engine indications within operating limits.  There are no operating limitations for the AVM system; therefore, there are no flight crew actions (or procedures) based solely on a response to engine vibration indications.


Certain engine malfunctions result in airframe vibrations from a windmilling engine.  As the airplane transitions from cruise to landing, there can be multiple, narrow regions of altitudes and airspeeds where the vibration level can become severe.  In general, airframe vibrations can best be reduced by descending and reducing airspeed.  However, if after descending and reducing airspeed, the existing vibration level is unacceptable, and if it is impractical to further reduce airspeed, the vibration level may be reduced to a previous, lower level by a slight increase in airspeed.


Limitations


Three engine manufacturers have supplied the powerplant for the B747 Classics:

Pratt & Whitney, Rolls Royce and General Electric

For the -200 these were the:

PW JT9D-7R4G2, RR RB211-524D4 & GE CF6-50E2.



Engine thrust per engine is:


PW 54,750 lbf (244 kN)

RR 53,000 lbf (236 kN)

G
E 52,500 lbf (234 kN)

             CF6 Max EGT Acceleration: 960 °C (2 minutes)*           

        CF6 Max EGT Continuous: 910 °C

             CF6 Max EGT Start: 750 °C (900 °C allowed for up to 40 seconds)

             CF6 Max EGT Takeoff: 945 °C (5 minutes)

             CF6 N1 RPM: 118.5%

             CF6 N2 RPM: 109.5%

             JT9D Max EGT Acceleration: 660ºC (2 minutes)
       
JT9D Max EGT Continuous: 620ºC

        JT9D Max EGT Start: 535ºC

        JT9D Max EGT Takeoff: 685ºC (5 minutes)

        JT9D N1 RPM: 106.2/105.8%* 

        JT9D N2 RPM: 103.5%
























































Pratt & Whitney JT9D: http://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT9D

General Electric CF6 engines:  http://en.wikipedia.org/wiki/General_Electric_CF6-50

Rolls Royce RB211: http://en.wikipedia.org/wiki/Rolls-Royce_RB211
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