Temperature Datum System

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Temperature Datum System Temperature Datum System

Author: Kev Mc HenryAuthor: Kev Mc Henry

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ObjectivesObjectives

• Describe the systemDescribe the system

• Identify the components and their locationIdentify the components and their location

• List significant specificationsList significant specifications

• Describe the system interfaceDescribe the system interface

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Temperature Datum SystemTemperature Datum System

• The Temperature Datum (TD) system is used to The Temperature Datum (TD) system is used to electronically trim the fuel to the engine.electronically trim the fuel to the engine.

• The TD system will:The TD system will:

a. Provide over-temperature protection during start and in a. Provide over-temperature protection during start and in flight.flight.

b. Maintain a selected temperature in flight.b. Maintain a selected temperature in flight.

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Components in the TD system are: Components in the TD system are: 1.1. The Speed Sense Control.The Speed Sense Control.

2.2. The Thermocouples.The Thermocouples.

3.3. The TD Control switch.The TD Control switch.

4.4. The TD amplifier.The TD amplifier.

5.5. The TD valve.The TD valve.

6.6. The Co-ordinator/Discriminator.The Co-ordinator/Discriminator.

7.7. The electronic Fuel Correction lights.The electronic Fuel Correction lights.

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TD OverviewTD Overview

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SpeedSpeedSenseSenseControlControl

TDTDValveValve

Co-ordinator/Co-ordinator/DiscriminatorDiscriminator

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Fuel System Tubing Fuel System Tubing

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ThermocouplesThermocouples

TDTDAmplifierAmplifier


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Electronic FuelElectronic FuelCorrection LightsCorrection Lights

TD ControlTD ControlSwitchesSwitches


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Motor/Motor/GeneratorGenerator

Take ResetTake ResetSolenoidSolenoid

BypassBypassValveValve

120% of Required120% of RequiredFuel in from FCUFuel in from FCU

CorrectedCorrectedFuel OutFuel Out

Bypassed FuelBypassed Fuel(5% - 70% of input fuel)(5% - 70% of input fuel)

50% Take50% TakeStopStop


VenturiVenturi

Temperature Datum ValveTemperature Datum Valve

Null OrificeNull Orifice

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Motor/Motor/GeneratorGenerator

Take ResetTake ResetSolenoidSolenoid

BypassBypassValveValve

120% of Required120% of RequiredFuel in from FCUFuel in from FCU

CorrectedCorrectedFuel OutFuel Out

Bypassed FuelBypassed Fuel(5% - 70% of input fuel)(5% - 70% of input fuel)



VenturiVenturi

Temperature Datum ValveTemperature Datum Valve

Null OrificeNull Orifice

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120%120%inin

100%100%outout

NULLNULL(always bypass 20%)(always bypass 20%)

Bypass NeedleBypass Needle

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120%120%inin

100%100%outout

120%120%inin

115%115%outout



MAX PUT + 15%MAX PUT + 15%(bypass 5%)(bypass 5%)

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120%120%inin

100%100%outout

120%120%inin

115%115%outout

120%120%inin

80%/50%80%/50%outout


MAX PUT + 15%MAX PUT + 15%(bypass 5%)(bypass 5%)

MAX TAKE - 20%/50%MAX TAKE - 20%/50%(bypass 40%/70%)(bypass 40%/70%)


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TD Valve AdjustmentTD Valve Adjustment

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Temperature Datum Amplifier Temperature Datum Amplifier

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TD Amp InstalledTD Amp Installed

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T. D. System OperationT. D. System Operation

3 things affect the operation of the T.D. system:3 things affect the operation of the T.D. system:

1.1. Position of the TD control switch. (NULL - LOCKED - Position of the TD control switch. (NULL - LOCKED - AUTO).AUTO).

2.2. Engine RPM. (<94% & >94%).Engine RPM. (<94% & >94%).

3.3. Throttle position (<66Throttle position (<66OO & >66 & >66OO).).

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• TD Control switch to NULL:TD Control switch to NULL:

If the TD control switch is in the NULL position, the TD If the TD control switch is in the NULL position, the TD Valve will remain in 20% bypass position.Valve will remain in 20% bypass position.

In NULL, the Fuel Correction lights behave in the same In NULL, the Fuel Correction lights behave in the same manner as for AUTO but the TD valve will not move.manner as for AUTO but the TD valve will not move.

NB:NB: In ‘NULL’, > 66In ‘NULL’, > 66oo throttle, there is throttle, there is NONO Overtemperature protection if 1077Overtemperature protection if 1077oo is exceeded. is exceeded.

T. D. System Operation - NullT. D. System Operation - Null

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““NULL” TD System OFFNULL” TD System OFF

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T. D. System Operation - Start LimitingT. D. System Operation - Start Limiting

TD Control switch in AUTO:TD Control switch in AUTO:

Starting:Starting:

LSGI selected:LSGI selected:

RPM <94%.RPM <94%.

TD system in TD system in Start LimitingStart Limiting mode. mode.

Maximum permitted TIT - Maximum permitted TIT - 830830ooC.C.

Maximum ‘Take’ capability - Maximum ‘Take’ capability - 50%.50%.(Fuel is taken [trimmed] if temp >830(Fuel is taken [trimmed] if temp >830ooC).C).

Electronic Fuel Correction light - Electronic Fuel Correction light - ON.ON.

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Start LimitingStart Limiting

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Starting:Starting:

NGI selected:NGI selected:

RPM >94%.RPM >94%.

TD system in TD system in Normal LimitingNormal Limiting mode. mode.

Maximum permitted TIT - Maximum permitted TIT - 10771077ooC.C.

Maximum ‘Take’ capability - Maximum ‘Take’ capability - 20%.20%.(Fuel is taken [trimmed] if temp >1077(Fuel is taken [trimmed] if temp >1077ooC).C).

Electronic Fuel Correction light - Electronic Fuel Correction light - ON.ON.

T. D. System Operation - Normal Limiting T. D. System Operation - Normal Limiting

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Normal Limiting Normal Limiting

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On Speed, >66On Speed, >66oo throttle: throttle:

TIT @ crossover TIT @ crossover 820820ooC (+/- 20C (+/- 20ooC).C).

Temperature scheduled from Temperature scheduled from 820820ooC to 1077C to 1077ooC between 66C between 66oo and 90and 90oo throttle position. throttle position.

Maximum ‘Take’ - Maximum ‘Take’ - 20%.20%.

Maximum ‘Put’ - Maximum ‘Put’ - 15%.15%.

Electronic Fuel Correction light - Electronic Fuel Correction light - OUT.OUT.


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• TD Control switch in AUTO:TD Control switch in AUTO:

As the throttles are advanced through 66As the throttles are advanced through 66oo (crossover), the (crossover), the TD system normally ‘cuts back’ the fuel to set 820TD system normally ‘cuts back’ the fuel to set 820ooC (+/- C (+/- 2020ooC). This is known as the crossover bump.C). This is known as the crossover bump.

Between throttle settings of 66Between throttle settings of 66oo & 90 & 90oo , a specific , a specific temperature is scheduled. The TD valve will either ‘put’ or temperature is scheduled. The TD valve will either ‘put’ or ‘take’ fuel to achieve the required temperature.‘take’ fuel to achieve the required temperature.

T. D. System Operation - ControllingT. D. System Operation - Controlling

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Controlling (Sel Temp 820 - 1077°C)Controlling (Sel Temp 820 - 1077°C)

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• TD Control switch in LOCKED:TD Control switch in LOCKED:

The crossover ‘bump’ can be an inconvenience, especially The crossover ‘bump’ can be an inconvenience, especially during formation and tactical flying and also during take-during formation and tactical flying and also during take-off in very cold weather.off in very cold weather.

To overcome this, the TD valve is electronically locked in To overcome this, the TD valve is electronically locked in position and will alter the fuel hydro-mechanically with position and will alter the fuel hydro-mechanically with throttle selection.throttle selection.

The TD valves are normally locked in pairs, above The TD valves are normally locked in pairs, above crossover.crossover.


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THROTTLETHROTTLE00OO 1010OO 2020OO 3030OO 4040OO 5050OO 6060OO 7070OO 8080OO 9090OO

TTOORRQQUUEE

20002000

40004000

60006000

80008000

1000010000

1200012000

1400014000

1600016000

1800018000

20000200001818OO 6666OO

MAX TORQUE = 19600’’/LBSMAX TORQUE = 19600’’/LBS

10771077ooCC

600600ooCC

820820ooCC


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THROTTLE00OO 1010OO 2020OO 3030OO 4040OO 5050OO 6060OO 7070OO 8080OO 9090OO

TTOORRQQUUEE

20002000

40004000

60006000

80008000

1000010000

1200012000

1400014000

1600016000

1800018000

20000200001818OO

MAX TORQUE = 19600’’/LBSMAX TORQUE = 19600’’/LBS

Torque, Fuel flowTorque, Fuel flowand TIT reduce atand TIT reduce at

CrossoverCrossover

10771077ooCC

600600ooCC

CrossoverCrossover‘‘BUMP’BUMP’

820820ooCC

6666OO


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Locked In CorrectionLocked In Correction

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Overtemp Release Overtemp Release

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RRPPMM

0%0%


10%10%

20%20%

30%30%

40%40%

50%50%

60%60%

70%70%

80%80%

90%90%

100%100%1818OO 6666OO

94%94%

3434OO

GROUND

IDLE

IDLE

FLIGHT

CROSSOVER


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RRPPMM

0%0%


10%10%

20%20%

30%30%

40%40%

50%50%

60%60%

70%70%

80%80%

90%90%

100%100%1818OO 6666OO

94%94%

3434OO

GROUND

IDLE

IDLE

FLIGHT

CROSSOVER

STARTTEMP

LIMITINGMAX TEMPMAX TEMP

830830OOCCMAX TAKE

50%NO PUT

EFCLIGHT ON

GROUNDIDLE


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RRPPMM

0%0%


10%10%

20%20%

30%30%

40%40%

50%50%

60%60%

70%70%

80%80%

90%90%

100%100%1818OO 6666OO

94%94%NGINGI

3434OO

GROUND

IDLE

IDLE

FLIGHT

CROSSOVER

106%106%

STARTTEMP


830830OOCCMAX TAKE

50%NO PUT

EFCLIGHT ON

NORMALTEMPERATURE

LIMITINGUP TO 1077UP TO 1077OOCCOVERTEMP

PROTECTION@ 1077OC

MAX TAKE20%

NO PUTCAPABILITY

EFCLIGHT ON

GROUNDIDLE


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0%0%


10%10%

20%20%

30%30%

40%40%

50%50%

60%60%

70%70%

80%80%

90%90%

100%100%1818OO 6666OO

94%94%NGINGI

3434OO

GROUND

IDLE

IDLE

FLIGHT

CROSSOVER

106%106%

TEMPERATURECONTROLLING

820°C - 1077820°C - 1077OOCCSCHEDULED

AT 90O THROTTLEMAX TAKE

20%MAX PUT

+15%NONO OVERTEMPOVERTEMPPROTECTIONPROTECTION

IN AUTOIN AUTOEFC

LIGHT OUT(UNLESS O’TEMP

IN LOCKED)

STARTTEMP


830830OOCCMAX TAKE

50%

NORMALTEMPERATURE

LIMITINGUP TO 1077UP TO 1077OOCCOVERTEMP

PROTECTION@ 1077OC

MAX TAKE20%

NO PUTCAPABILITY

EFCLIGHT ON

GROUNDIDLE


RRPPMM

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The TD valve will only unlock if an over-temp occurs The TD valve will only unlock if an over-temp occurs (>1077(>1077ooC), or if ‘NULL’ or ‘AUTO’ is selected.C), or if ‘NULL’ or ‘AUTO’ is selected.

The Fuel Correction lights will remain in the state they The Fuel Correction lights will remain in the state they were in when locked was selected.were in when locked was selected.

If locked was selected above crossover, when an overtemp If locked was selected above crossover, when an overtemp occurs the Fuel Correction light will come on to advise occurs the Fuel Correction light will come on to advise that controlling action has occurred.that controlling action has occurred.


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If it is required to re-lock the TD valves, the throttles must If it is required to re-lock the TD valves, the throttles must be selected back above crossover with the TD switches in be selected back above crossover with the TD switches in AUTO then LOCKED re-selected.AUTO then LOCKED re-selected.


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ANY QUESTIONS?ANY QUESTIONS?

Temperature Datum System

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