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WHITE MESSAGE Require immediate crew attention. These messages are accompanied by flashing master warning, triple chime attenson with or without voice message or dedicated tone. Require immediate crew awareness and future crew action may be required in the form of alternate system selection or performance limitation. These message are accompanied by flashing master caution and a single chime. Indicate safe or normal system operation which require crew awareness, over and above the dark cockpit philosophy. Indicate minor failures or reduction in systems capability, which require no crew action.

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07/06/21

Message Overview:

Message Name:

INTER TURBINE TEMPERATURE (ITT) SPLIT BETWEEN ENGINES

Message Code: 772OBS002
Effectivity: All
System: Temperature Indicating System
System Description: 77-20-00
Schematic Diagram: 77-20-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wiring Diagram: 77-20-01 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Message Description:

Significant Inter Turbine Temperature (ITT) split between the Left Hand (LH) and Right Hand (RH) Engine.

Possible Causes:

  • Inter Turbine Temperature (ITT) Thermocouple Probe
  • Engine Electronic Controller (EEC)
  • Bleed Valve Solenoid Block (BVSB)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter:

Quick Links:

Electrical/Electronic Safety Precautions AMM 24-00-00-910-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Access to Active Faults AMM 45-45-00-970-802 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Engine Safety Precautions AMM 71-00-00-910-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Opening of the Cowls AMM 71-10-00-010-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Closing of the Cowls AMM 71-10-00-410-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Visual Check of the HP Compressor Airflow-Control System AMM 75-31-00-210-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Thrust Reverser Safety Precautions AMM 78-30-00-910-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Deactivation of the Thrust Reverser (for Maintenance) AMM 78-30-00-040-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Activation of the Thrust Reverser (for Maintenance) AMM 78-30-00-440-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Resistance Check of the Harnesses EMM 71-50-00-760-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Eng Electronic Controller (EEC) EMM 73-21-01-000-801-B00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Eng Electronic Controller (EEC) EMM 73-21-01-400-801-B00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Data Entry Plug (DEP) EMM 73-21-02-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Data Entry Plug (DEP) EMM 73-21-02-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Pre SB 73-101443: Trim the Data Entry Plug (DEP) EMM 73-21-02-820-801-A01 [ Global Express ]  [ G5000 ]  [ Global XRS ]
SB 73-101443: Trim the Data Entry Plug (DEP) EMM 73-21-02-820-801-B01 [ Global Express ]  [ G5000 ]  [ Global XRS ]
SB 73-101443: Re-configure/Repair the Data Entry Plug (DEP) EMM 73-21-02-820-801-B02 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Pre SB 75-100385: Engine Bleed System - Do a Leak Check EMM 75-00-00-790-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Inter Turbine Temperature (ITT) Harness EMM 77-21-02-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Inter Turbine Temperature (ITT) Harness EMM 77-21-02-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Troubleshooting Recommendations:

  1. Access CAIMS Active Faults. Are any of the following messages present?

    1. If YES, troubleshoot these messages first and continue with next step.
    2. If NO, continue with next step.

  2. Record the value of the ITT split.

    1. If it is not more than 15 degrees, no maintenance action is required so do close out.
    2. If it is more than 15 degrees, continue with next step.

  3. Check whether the electrical loads (VFGs), hydraulic loads and customer bleed (packs) are identical for both engines.

    1. If they are not identical, ensure that both engines are equally loaded (before ITT is compared) and go to step 2.
    2. If they are identical, continue with next step.

  4. Check whether the LH/RH engine deterioration (life and flying hours) and last engine test certificates (TGT versus speeds) are comparable.

    1. If the LH/RH engine deterioration (life and flying hours) and last engine test certificates (ITT versus speeds) are not identical, go to step 6.
    2. If the LH/RH engine deterioration (life and flying hours) and last engine test certificates (ITT versus speeds) are identical, continue with next step.

  5. Check if the EPR actual for both engines are identical.

    1. If they are not identical ensure that both engines are running at the same EPR (before ITT is compared) and go to step 2.
    2. If the EPR actual or both engines are identical, go to step 7.

  6. Check if the ITT is higher on the less deteriorated engine.

    1. If the ITT is not higher on the less deteriorated engine, go to step 2.
    2. If the ITT is higher on the less deteriorated engine, go to step 5.

  7. Check the DEP configuration.

    1. If the configuration of the DEP (flight deck) against the engine log-book is wrong, re-configure/repair the DEP in accordance with the EMM TASK 73-21-02-820-801-A01 and EMM TASK 73-21-02-820-801-B02 and continue with next step.
    2. If the configuration of the DEP (flight deck) against the engine log-book is correct, continue with next step.

  8. Swap EEC. Did the higher ITT follow to the other engine?

    1. If YES, replace defective EEC and do close out.
    2. If NO, continue with next step.

  9. Compare the HP speeds (N2) between the LH and RH engines.

    1. If the HP speeds (N2) do not match, go to step 7.
    2. If the HP speeds (N2) match, continue with next step.

  10. Check if the higher ITT corresponds to a higher fuel flow and/or N2 speed.

    1. If NO, go to step 13.
    2. If YES, continue with next step.

  11. Carry out an inspection of the engine handling bleed system (Pipes, pipe connections, etc).

    1. If damages are found, repair EMM as required and do close out.
    2. If no damages are found, continue with next step.

  12. Perform a "free movement" check of the stage 5 Handling Bleed Valve (HBV) and stage 8 HBV.

    1. If the tests pass, replace the Bleed Valve Solenoid Block (BVSB) and do close out.
    2. If the tests fail, replace the defective valve and do close out.
      NOTE: Inspect the stage 8 HBV cover P-seal. If the P-seal shows signs of damage or overheating, contact Rolls Royce Deutschland service engineering.

  13. Are there P50 or T20 related maintenance messages?

    1. If YES, apply corrective action and do close out.
    2. If NO, continue with next step.

  14. Perform the ITT probe Insulation Resistance (IR) test and NTO 87 on the engine with the lower ITT reading (EMM TASK 71-50-00-760-801).

    1. If the test fails, replace the defective ITT probe and do close out.
    2. If the test passes, continue with next step.

  15. Replace the ITT Harness. Is the ITT split still present?

    1. If NO, do close out.
    2. If YES, go to step 8 it not already carried out. If step 8 has already been carried out, continue with next step.

  16. Perform AMM TASK 75-31-00-210-801 - Visual Check of the HP Compressor - Airflow Control System.

    1. If there is any damage, apply corrective action and do close out.
    2. If there is no damage, continue with next step.

  17. Contact Rolls Royce Deutschland service engineering.
  18. Do close out.
     

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