4K-1

Pratt and Whitney JT15D-4 Engine

Citation I/II/SII For training onlyJune 1997

Po

wer

pla

nt

Sys

tem

s

4K-2 For training only Citation I/II/SIIJune 1997

Powerplant

Citation I/II/SII For training only 4K-3May 1998

TO BEARINGS 1, 2, 3

BEARINGS1, 2, 3, 3

RESERVOIR

GR

AVIT

Y FE

ED T

O G

EAR

BO

X

PUMP ASSEMBLY

PRESSUREELEMENT

PRESSURERELIEF VALVE

OILCOOLER

PRESS

OILFILTER

SCAVENGEELEMENTS

TO BEARINGS 1, 2, 3 TO BEARINGS 3 AND 4

SYSTEM DRAIN

BEARING 4

SUPPLY

PUMP PRESSURE

RETURN

1 2

1 2

OIL PRESSWARN

LH RH

OIL

PRESS

L

OIL

PRESS

R

100

80

60

40

20

0PSI

OFF

OIL

TEMP

L

OIL

TEMP

R

120

100

80

60

40

20

0� C

OFFL OIL

PRESS LO

TEMP

Engine Oil System

4K-4 For training only Citation I/II/SIIJune 1997

Fuel Control System

MOTIVEFLOWVALVE

FROMFUELTANK

TOFLOW

METER

BLEEDAIR

SHUTOFF

FUEL NOZZLES

AUTOMATICFUEL SHUTOFF

CONTROL

OILCOOLER

FUELCONTROL

UNITFUELFLOW

ENGINEDRIVENPUMP

FUELDIV.

IGNITIONSTEPMODULATOR

MOTIVE FLOWTO FUEL TANK

Citation I/II/SII For training only 4K-5June 1997

Powerplant

PowerplantTwo Pratt & Whitney of Canada JT15D engines power theCessna Citation aircraft. The JT15D is a lightweight, two-spool,medium bypass turbofan that produces between 2,200 and2,550 lbs of static takeoff thrust at sea level (see Table 4K-1).After air enters the engine inlet, a front fan driven by the lowpressure (LP) turbine accelerates air rearward toward the axial(JT15D-4/-4B only) and centrifugal compressors and the full-length, annular bypass duct. Approximately 75% (-1/-1A/-1B) to66% (-4/-4B) of the total air flows around the engine corethrough the bypass duct.After the air passes through the fan, an axial compressor, dri-ven by the low pressure turbine, accelerates the air beforepassing it to the centrifugal compressor. The compressor, dri-ven by the high-pressure (LP) turbine, slings air outward toaccelerate it to a high-velocity, low-pressure flow. The diffuserconverts the high-velocity flow into a low-velocity, high-pressureflow before it reaches the combustion section.

Static ThrustEngine Takeoff Max Aircraft

Continuous

JT15D-1 2,200 2,090 Citation

JT15D-1A 2,200 2,090 Citation I

JT15D-1B 2,200 2,090 Citation I

JT15D-4 2,500 2,375 Citation II

JT15D-4B 2,500 2,375 Citation SII

Table 4K-1; Pratt and Whitney JT15D Engines

4K-6 For training only Citation I/II/SIIJune 1997

After entering the annular, reverse-flow combustion section, theairflow makes a 180° turn forward, then mixes with fuel intro-duced by the fuel nozzles. Initially ignited by two igniter plugs,the air/fuel mixture burns and expands. The hot combustiongases then flow to the exit duct where they make a 180° turnbefore reaching the HP turbine. As the high velocity gas streampasses through the turbine, the turbine rotates to extract ener-gy to drive the centrifugal compressor. The combustion gasesthen flow through the two-stage LP turbine to rotate it. The LPturbine, in turn, drives the axial LP compressor (JT15D-4/-4Bonly) and front fan. After exiting the turbine section, the gasstream enters the exhaust duct where it mixes with bypass airto produce forward thrust.

Lubrication SystemThe engine-driven oil pump draws oil from a tank and provides itunder pressure through a fuel/oil cooler and filter to the enginebearings, bevel and spur gears, and accessory gearbox.After lubricating, cooling, and cleaning the engine, oil drains fromthe bearings into the accessory gearbox and from the No. 4engine bearing into a sump. The oil pump’s scavenge elementsdraw oil from the sump areas to the oil tank.A breather system relieves excess air pressure from the lubrica-tion system to prevent pump cavitation and excess system pressure.Pressure and temperature transmitters in the lubrication systemdrive the vertical tape OIL PRESS and OIL TEMP gages. Belowapproximately 35 PSI, the respective OIL PRESS LO or OILPRESS WARN annunciator illuminates.

Powerplant

Citation I/II/SII For training only 4K-7June 1997

Fuel and Fuel ControlUnder pressure from the wing fuel system, fuel flows through thefirewall shutoff valve to the engine-driven fuel pump at approxi-mately 20 to 30 PSI. A pressure switch between the firewall shut-off valve and engine pump illuminates the FUEL PRESS LO orFUEL LOW PRESS annunciator if fuel pressure drops belowapproximately 5 PSI. Low fuel pressure automatically turns theelectric fuel boost pump on. The engine-driven fuel pump thendelivers fuel at approximately 500 to 700 PSI through a filter tothe fuel control unit (FCU).Movement of a throttle lever controls the FCU through direct link-age. Each throttle lever has a mechanical stop that prevents inad-vertent selection of CUTOFF and a latch that must be released toadvance the throttle from CUTOFF to IDLE. In response to throt-tle movement, the FCU meters fuel to provide efficient engineoperation based on engine N2 speed, ambient and compressordischarge pressure, compressor inlet temperature, and throttleposition during starting, acceleration, and shutdown.Metered fuel from the FCU flows through the fuel/oil cooler to theflow divider valve and motive flow valve. A fuel flow transmitterbetween the FCU and cooler drives the vertical tape FUELFLOW gage. The gage shows fuel flow from 0 to 2,000 pounds-per-hour (PPH).In the flow divider valve, the fuel flow splits to supply the primaryand secondary manifolds. The divider valve also controls fuelpressure to the primary manifold during engine start and ensuresthat fuel does not enter the manifolds until it reaches a minimumpressure.The motive flow valve supplies low pressure high-flow motiveflow fuel to the fuel system’s primary ejector pump.From the flow divider valve, fuel flows to the fuel manifold assem-bly. The assembly then distributes fuel to the fuel nozzle primaryand secondary passages. The fuel nozzles deliver a finely atom-ized spray of fuel into the engine’s combustion chamber.

4K-8 For training only Citation I/II/SIIJune 1997

An emergency fuel shutoff system prevents engine overspeedshould a catastrophic failure occur by cutting fuel flow to theengine. Axial displacement of the low pressure turbine shaft acti-vates a plunger in the shutoff valve piston. The piston assembly,in turn, activates the fuel inlet and emergency shutoff valve. Fuelflow stops and the engine shuts down.

IgnitionDuring the engine start cycle, advancing a throttle out of the cut-off position supplies power from the Hot Battery bus to the igni-tion exciters. The exciters provide high-voltage electrical pulsesto the two ignition plugs. The plugs, extending into the combus-tion chamber, fire to ignite the fuel/air mixture. When the enginestart cycle terminates, the ignition system deactivates.Placing an IGNITION switch in ON supplies power for continuousignition system operation. During ignition system operation agreen light above each switch illuminates. Placing an ENGINEANTI-ICE switch to ON also provides engine ignition.

ControlEach throttle lever mechanically connects with its engine FCUthrough cables and bellcranks and controls the FCU from cutoffto full thrust. A mechanical stop prevents inadvertent selection ofthe CUTOFF position. A latch must be raised before the throttlecan be moved from CUTOFF to the IDLE position. In responseto throttle movement, the FCU then meters fuel to the enginebased on N2 RPM.

During intentional and unintentional thrust reverser operation, afeedback cable between the thrust reverser actuating mecha-nism, FCU, and throttle lever ensures that the FCU is in the idlethrust position during thrust reverser deployment and stowing.This mechanism also drives the associated throttle lever to theidle position should an inadvertent deployment occur.

Powerplant

Citation I/II/SII For training only 4K-9June 1997

Engine SynchronizerWhen operating, the engine synchronizer provides automatic N1or N2 synchronization between the left (master) and right (slave)engines. With the ENGINE SYNC switch in FAN or TURB, thesystem compares the right engine’s N1 or N2 speed (whicheveris selected) to the left engine. If there is a speed mismatch, thesystem trims the right engine’s FCU through an actuator to eitherincrease or decrease engine speed. The system has a 1.5% N1or 1.0% N2 RPM authority range. The system does not operateif the slave engine speed, when compared to the master, is outof this range. This prevents the right engine from synchronizingwith a failing left engine.

4K-10 For training only Citation I/II/SIIJune 1997

Powerplant

Citation I/II/SII For training onlyMay 1998

Thrust Reversers

4K-11

UNLOCK

DEPLOY

BOTTLE 1ARMEDPUSH

LHENGFIRE

BOTTLE 2ARMEDPUSH

EMER

NORM

STOW

SW

ARM EMER

NORM

HYDPRESS ON

LH THRUREV

RETURN

1,500 PSI

SPRING

ISOLATIONVALVE

200 PSIPRESSURESWITCH

STOWSOLENOID

STOW

CONTROL VALVEDEPLOY POSITION SHOWN

DEPLOY

DEPLOYSOLENOID

AIGND

RESTRICTOR

SQUAT SWITCH

RIGHT THRUST REVERSER

STOWED

UNLOCK

STOW LIMITSWITCH

DEPLOYED

STOWED ORIN TRANSIT

DEPLOYLIMIT SWITCH

THROTTLELOCKSOLENOID

DEPLOYEDPOSITIONSHOWN

STOW

DEPLOYRH STOWDEPLOYSWITCH

TO LH T/RTO LH STOW

RH THRUREV

WARN LITE 1

5A

PRESSURE

RETURN

STATIC

STOW

SW

UNLOCK

ARM

DEPLOY

RH CROSSOVER BUS

7.5 A

HYD PRESSON

LH MAIN EXT BUS

RHENGFIRE

7.5 A

4K-12 For training only Citation I/II/SIIJune 1997