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Temperature Datum System

Temperature Datum System. Author: Kev Mc Henry. Describe the system Identify the components and their location List significant specifications Describe the system interface. Objectives. The Temperature Datum (TD) system is used to electronically trim the fuel to the engine.

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Temperature Datum System

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  1. Temperature Datum System Author: Kev Mc Henry

  2. Describe the system • Identify the components and their location • List significant specifications • Describe the system interface Objectives

  3. The Temperature Datum (TD) system is used to electronically trim the fuel to the engine. • The TD system will: • a. Provide over-temperature protection during start and in flight. • b. Maintain a selected temperature in flight. Temperature Datum System

  4. Components in the TD system are: • The Speed Sense Control. • The Thermocouples. • The TD Control switch. • The TD amplifier. • The TD valve. • The Co-ordinator/Discriminator. • The electronic Fuel Correction lights. Temperature Datum System

  5. TD Overview

  6. Co-ordinator/ Discriminator Speed Sense Control TD Valve Temperature Datum System

  7. Fuel System Tubing

  8. TD Amplifier Thermocouples Temperature Datum System

  9. Electronic Fuel Correction Lights TD Control Switches Temperature Datum System

  10. Corrected Fuel Out Null Orifice Bypass Valve Motor/ Generator Take Reset Solenoid Venturi 20% Take Stop 50% Take Stop Bypassed Fuel (5% - 70% of input fuel) 120% of Required Fuel in from FCU Temperature Datum Valve

  11. Corrected Fuel Out Null Orifice Bypass Valve Motor/ Generator Take Reset Solenoid Venturi 20% Take Stop 50% Take Stop Bypassed Fuel (5% - 70% of input fuel) 120% of Required Fuel in from FCU Temperature Datum Valve

  12. NULL (always bypass 20%) 120% in 100% out Bypass Needle

  13. NULL (always bypass 20%) MAX PUT + 15% (bypass 5%) 120% in 100% out 120% in 115% out Bypass Needle

  14. NULL (always bypass 20%) MAX PUT + 15% (bypass 5%) MAX TAKE - 20%/50% (bypass 40%/70%) 120% in 100% out 120% in 115% out 120% in 80%/50% out Bypass Needle

  15. TD Valve Adjustment

  16. Temperature Datum Amplifier

  17. TD Amp Installed

  18. 3 things affect the operation of the T.D. system: • Position of the TD control switch. (NULL - LOCKED - AUTO). • Engine RPM. (<94% & >94%). • Throttle position (<66O & >66O). T. D. System Operation

  19. TD Control switch to NULL: • If the TD control switch is in the NULL position, the TD Valve will remain in 20% bypass position. • In NULL, the Fuel Correction lights behave in the same manner as for AUTO but the TD valve will not move. • NB:In ‘NULL’, > 66o throttle, there is NO Overtemperature protection if 1077o is exceeded. T. D. System Operation - Null

  20. “NULL” TD System OFF

  21. TD Control switch in AUTO: • Starting: • LSGI selected: • RPM <94%. • TD system in Start Limiting mode. • Maximum permitted TIT - 830oC. • Maximum ‘Take’ capability - 50%. (Fuel is taken [trimmed] if temp >830oC). • Electronic Fuel Correction light - ON. T. D. System Operation - Start Limiting

  22. Start Limiting

  23. TD Control switch in AUTO: • Starting: • NGI selected: • RPM >94%. • TD system in Normal Limiting mode. • Maximum permitted TIT - 1077oC. • Maximum ‘Take’ capability - 20%. (Fuel is taken [trimmed] if temp >1077oC). • Electronic Fuel Correction light - ON. T. D. System Operation - Normal Limiting

  24. Normal Limiting

  25. TD Control switch in AUTO: On Speed, >66o throttle: TIT @ crossover 820oC (+/- 20oC). Temperature scheduled from 820oC to 1077oC between 66o and 90o throttle position. Maximum ‘Take’ - 20%. Maximum ‘Put’ - 15%. Electronic Fuel Correction light - OUT. T. D. System Operation

  26. TD Control switch in AUTO: • As the throttles are advanced through 66o (crossover), the TD system normally ‘cuts back’ the fuel to set 820oC (+/- 20oC). This is known as the crossover bump. • Between throttle settings of 66o & 90o , a specific temperature is scheduled. The TD valve will either ‘put’ or ‘take’ fuel to achieve the required temperature. T. D. System Operation - Controlling

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

  28. TD Control switch in LOCKED: • The crossover ‘bump’ can be an inconvenience, especially during formation and tactical flying and also during take-off in very cold weather. • To overcome this, the TD valve is electronically locked in position and will alter the fuel hydro-mechanically with throttle selection. • The TD valves are normally locked in pairs, above crossover. T. D. System Operation

  29. 18O 66O MAX TORQUE = 19600’’/LBS 20000 1077oC 18000 16000 14000 12000 820oC T O R Q U E 10000 8000 6000 4000 2000 600oC 0O 10O 20O 30O 40O 50O 60O 70O 80O 90O T. D. System Operation THROTTLE

  30. 18O 66O MAX TORQUE = 19600’’/LBS 20000 1077oC 18000 16000 Torque, Fuel flow and TIT reduce at Crossover 14000 12000 820oC T O R Q U E 10000 8000 Crossover ‘BUMP’ 6000 4000 2000 600oC 0O 10O 20O 30O 40O 50O 60O 70O 80O 90O T. D. System Operation THROTTLE

  31. Locked In Correction

  32. Overtemp Release

  33. 18O 34O 66O 100% 94% 90% 80% 70% 60% R P M 50% C R O S S O V E R 40% G R O U N D F L I G H T 30% I D L E I D L E 20% 10% 0% 0O 10O 20O 30O 40O 50O 60O 70O 80O 90O T. D. System Operation THROTTLE

  34. 18O 34O 66O 100% 94% 90% GROUND IDLE 80% 70% START TEMP LIMITING MAX TEMP 830OC MAX TAKE 50% NO PUT EFC LIGHT ON 60% R P M 50% C R O S S O V E R 40% G R O U N D F L I G H T 30% I D L E I D L E 20% 10% 0% 0O 10O 20O 30O 40O 50O 60O 70O 80O 90O T. D. System Operation THROTTLE

  35. 106% 18O 34O 66O 100% NGI 94% 90% NORMAL TEMPERATURE LIMITING UP TO 1077OC OVERTEMP PROTECTION @ 1077OC MAX TAKE 20% NO PUT CAPABILITY EFC LIGHT ON GROUND IDLE 80% 70% START TEMP LIMITING MAX TEMP 830OC MAX TAKE 50% NO PUT EFC LIGHT ON 60% R P M 50% C R O S S O V E R 40% G R O U N D F L I G H T 30% I D L E I D L E 20% 10% 0% 0O 10O 20O 30O 40O 50O 60O 70O 80O 90O T. D. System Operation THROTTLE

  36. 106% 18O 34O 66O 100% NGI 94% 90% NORMAL TEMPERATURE LIMITING UP TO 1077OC OVERTEMP PROTECTION @ 1077OC MAX TAKE 20% NO PUT CAPABILITY EFC LIGHT ON TEMPERATURE CONTROLLING 820°C - 1077OC SCHEDULED AT 90O THROTTLE MAX TAKE 20% MAX PUT +15% NOOVERTEMP PROTECTION IN AUTO EFC LIGHT OUT (UNLESS O’TEMP IN LOCKED) GROUND IDLE 80% 70% START TEMP LIMITING MAX TEMP 830OC MAX TAKE 50% 60% R P M 50% C R O S S O V E R 40% G R O U N D F L I G H T 30% I D L E I D L E 20% 10% 0% 0O 10O 20O 30O 40O 50O 60O 70O 80O 90O T. D. System Operation THROTTLE

  37. TD Control switch in LOCKED: • The TD valve will only unlock if an over-temp occurs (>1077oC), or if ‘NULL’ or ‘AUTO’ is selected. • The Fuel Correction lights will remain in the state they were in when locked was selected. • If locked was selected above crossover, when an overtemp occurs the Fuel Correction light will come on to advise that controlling action has occurred. T. D. System Operation

  38. TD Control switch in LOCKED: • If it is required to re-lock the TD valves, the throttles must be selected back above crossover with the TD switches in AUTO then LOCKED re-selected. T. D. System Operation

  39. ANY QUESTIONS?

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