Temperature Datum System Author: Kev Mc Henry

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

Temperature Datum System 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. 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 TD system requirements 2

Temperature Datum System 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. The components in the TD system are: 1. The Speed Sense Control. 2. The Thermocouples. 3. The TD Control switch. 4. The TD amplifier. 5. The TD valve. 6. The Co-ordinator/Discriminator. 7. The electronic Fuel Correction lights. Temperature Datum System Photo of TD components 3

TD Overview

Temperature Datum System Co-ordinator/ Discriminator Speed Sense Control TD Valve Show the location of the following: The Speed Sense Control. The Co-ordinator/Discriminator. The TD valve. Temperature Datum System Photo of TD components 4

Fuel System Tubing TD system Operation This slide and the next will explain the ‘Cross-over’ bump. Crossover occurs at 66o throttle position. The TD system changes from Temperature Limiting to Temperature controlling. This change is effected by a micro-switch in the Co-ordinator /Discriminator. Fuel System Tubing TD system Operation 18

Temperature Datum System TD Amplifier Thermocouples Show the location of the following: The Thermocouples. The TD amplifier. Temperature Datum System Photo of TD components 5

Temperature Datum System Electronic Fuel Correction Lights TD Control Switches Show the location of the following: The Electronic fuel correction lights. The TD control switches. Temperature Datum System TD valve 6

Temperature Datum Valve Corrected Fuel Out Null Orifice Bypass Valve Motor/ Generator Take Reset Solenoid Venturi Recap the basic component parts of the TD valve. 20% Take Stop 50% Take Stop Bypassed Fuel (5% - 70% of input fuel) 120% of Required Fuel in from FCU Temperature Datum Valve Bypass valve - null 7

Temperature Datum Valve 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

Bypass Needle NULL (always bypass 20%) 120% in 100% out Explain the standard bypass rate of 20% when the needle is in NULL. Bypass Needle Bypass valve - Max put 8

Bypass Needle NULL (always bypass 20%) MAX PUT + 15% (bypass 5%) 120% in 100% out 120% in 115% out Explain the bypass rate when the needle is at MAX PUT. Bypass Needle Bypass valve - Max take 9

Bypass Needle 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 Explain the bypass rate when the needle is at MAX TAKE. (50% up to 94% RPM and 20% above that). Bypass Needle TD system Operation 10

TD Valve Adjustment

Temperature Datum Amplifier

TD Amp Installed

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). 3 things affect the operation of the TD system: 1. Position of the TD control switch. (NULL - LOCKED - AUTO). 2. Engine RPM. (<94% & >94%). 3. Throttle position (<66O & >66O). T. D. System Operation TD system Operation 11

T. D. System Operation - Null 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. TD Control switch in 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. T. D. System Operation - Null TD Controlling check 23

“NULL” TD System OFF

T. D. System Operation - Start Limiting 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. 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 TD system Operation 12

Start Limiting

T. D. System Operation - Normal Limiting 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. 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 TD system Operation 13

Normal Limiting

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. TD control switch in AUTO: On Speed, >66o throttle: TIT @ crossover 820oC (+/- 20oC). Temperature scheduled from 820oC to 1077oC (1067oC - 1083oC) between 66o and 90o throttle position. Maximum ‘Take’ - 20%. Maximum ‘Put’ - 15%. Electronic Fuel Correction light - OUT. T. D. System Operation TD system Operation 15

T. D. System Operation - Controlling 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. 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 TD system Operation 16

Controlling (Sel Temp 820 - 1077°C)

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. 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 TD system Operation 20

T. D. System Operation 18O MAX TORQUE = 19600’’/LBS 66O 20000 1077oC 18000 16000 14000 12000 T O R Q U E 820oC 10000 8000 6000 4000 This slide and the next will explain the ‘Cross-over’ bump. Crossover occurs at 66o throttle position. The TD system changes from Temperature Limiting to Temperature controlling. This change is effected by a micro-switch in the Co-ordinator /Discriminator. 2000 600oC 0O 10O 20O 30O 40O 50O 60O 70O 80O 90O T. D. System Operation THROTTLE TD system Operation 18

T. D. System Operation 18O MAX TORQUE = 19600’’/LBS 66O 20000 1077oC 18000 16000 Torque, Fuel flow and TIT reduce at Crossover 14000 12000 T O R Q U E 820oC 10000 8000 Crossover ‘BUMP’ 6000 4000 The TD system causes a temperature of 820oC +/- 20oC to be scheduled. Generally speaking the TD system will have to cut back the amount of fuel going to the burners to achieve the desired temperature. This cut-back can be seen on the TIT, torque and fuel flow gauges along with the Fuel Correction lights going out. 2000 600oC 0O 10O 20O 30O 40O 50O 60O 70O 80O 90O T. D. System Operation THROTTLE TD system Operation 19

Locked In Correction

Overtemp Release

T. D. System Operation 18O 34O 66O 100% 94% 90% 80% 70% 60% R P M 50% C R O S V E 40% G R O U N D F L I G H T 30% I D L E I D L E 20% This and the next 3 slides give a graphic representation of the operation of the TD system. 10% 0% 0O 10O 20O 30O 40O 50O 60O 70O 80O 90O T. D. System Operation THROTTLE TD system Operation 25

T. D. System Operation 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 V E 40% G R O U N D F L I G H T 30% I D L E I D L E 20% Ground Idle - Throttles in Ground Idle detent - RPM < 94%. Start Temp limiting - 830oC. Max take 50%, No put capability. Electronic Fuel Correction light ON. 10% 0% 0O 10O 20O 30O 40O 50O 60O 70O 80O 90O T. D. System Operation THROTTLE TD system Operation 26

T. D. System Operation 106% 18O 34O 66O 100% NGI 94% 90% GROUND IDLE NORMAL TEMPERATURE LIMITING UP TO 1077OC OVERTEMP PROTECTION @ 1077OC MAX TAKE 20% NO PUT CAPABILITY EFC LIGHT ON 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 V E 40% G R O U N D F L I G H T 30% I D L E I D L E 20% NGI up to 66o throttle, RPM > 94%. Normal Temp limiting - 1077oC (1067oC to 1083oC), Overtemp protection. Max take 20%, No put capability. Electronic Fuel Correction light ON. 10% 0% 0O 10O 20O 30O 40O 50O 60O 70O 80O 90O T. D. System Operation THROTTLE TD system Operation 27

T. D. System Operation 106% 18O 34O 66O 100% NGI 94% 90% GROUND IDLE 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% NO OVERTEMP PROTECTION IN AUTO EFC LIGHT OUT (UNLESS O’TEMP IN LOCKED) 80% 70% START TEMP LIMITING MAX TEMP 830OC MAX TAKE 50% 60% R P M 50% C R O S V E 40% G R O U N D F L I G H T 30% I D L E I D L E 20% > 66o throttle, RPM 100%. Temp Controlling - 820°C - 1077oC (1067oC to 1083oC) scheduled, NO Overtemp protection unless LOCKED has been selected. Max take 20%, Max Put +15%. Electronic Fuel Correction light OUT (unless O/Temp in LOCKED). 10% 0% 0O 10O 20O 30O 40O 50O 60O 70O 80O 90O T. D. System Operation THROTTLE TD system Operation 28

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. 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 TD system Operation 21

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. 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 TD system Operation 22

ANY QUESTIONS?