Fault Message:

L N1 SPEED CH B WRG/PROBE RNG

Fault Code:

7326227LBR

Associated CAS:

L FADEC FAIL
(Caution)

Engine Electronic Controller (EEC) senses that the signal from the N1 Speed Probe of channel B is out of limits. During engine operation the speed probe circuits are continuously monitored by the Full-Authority Digital Engine-Controller (FADEC).

• There are three Speed Probe inputs to the EEC: Channel A, Channel B and Shared
• The output from the N1 Speed Probe shared can be changed with the output from the N1 Speed Probe of channel B to let the aircraft be serviceable

• N1 Speed Probe Channel B
• N1 Speed Probe Shared
• Left Engine Electronic Controller (EEC)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Refer to Figure below.
   WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE DURING OR AFTER AN ENGINE OPERATION. THE ENGINE PARTS STAY HOT FOR APPROXIMATELY THREE HOURS AFTER THE ENGINE STOPS. THIS CAN CAUSE INJURY TO PERSONS.
   WARNING: BE CAREFUL IF YOU MUST DO WORK ON HOT COMPONENTS. USE APPROVED GLOVES AND PROTECTIVE CLOTHING. IF YOU DO NOT DO THIS, YOU CAN CAUSE INJURY TO PERSONS.
2. Perform the fault isolation for the N1 speed probe, on the EMS CDU, open the circuit breakers that follow:

   System Name	Circuit Breaker Name	Bus Name
   ENGINE	L ENG FUEL HPSOV	BATT
   ENGINE	L ENG IGN 1	BATT
   ENGINE	L ENG IGN 2	BATT
   ENGINE	L ENG START A	BATT
   ENGINE	L ENG START B	BATT
   ENGINE	L FADEC CH A	BATT
   ENGINE	L FADEC CH B	BATT

3. Perform a deactivation of the thrust reverser.
4. Open the cowls.
5. Perform a visual inspection of the interface wiring between EEC (P1046) and N1 speed probe (P1077).
   NOTE: Look specially for signs of damage adjacent to clip locations.

   1. If system check is not good, repair defective wiring as required and go to step 23.
   2. If system check is good, continue with next step.

6. Monitor the system to see if the fault message N1 SPEED CH B WRG/PROBE RNG occurs again.

   1. If the fault message is not active, go to step 23.
   2. If the fault message is active, continue with next step.

7. In the flight compartment, on the EMS CDU, open the circuit breakers that follow:

   System Name	Circuit Breaker Name	Bus Name
   ENGINE	L ENG FUEL HPSOV	BATT
   ENGINE	L ENG IGN 1	BATT
   ENGINE	L ENG IGN 2	BATT
   ENGINE	L ENG START A	BATT
   ENGINE	L ENG START B	BATT
   ENGINE	L FADEC CH A	BATT
   ENGINE	L FADEC CH B	BATT

   1. If the fault message N1 SPEED WRG/PROBE SHARED RNG does not show, go to step 9.
   2. If the fault message N1 SPEED WRG/PROBE SHARED RNG shows, then there is also a defective N1 speed probe shared, continue with next step.

8. Perform the troubleshooting procedure for N1 speed probe shared.
9. Change the output from the N1 speed probe shared with the output from the N1 speed probe for channel B as follows:

   1. Disconnect the connector P1077 for the N1 speed probe of channel B.
   2. Disconnect the connector P1076 for the N1 speed probe shared.
   3. Connect the connector P1077 to the interface receptacle for the N1 speed probe shared.
   4. Connect the connector P1076 to the interface receptacle for the N1 speed probe of channel B.
      NOTE: If the fault message N1 SPEED CH B WRG/PROBE RNG does not show again:

      • The problem is possibly moved to the N1 speed probe shared input.
      • The fault message N1 SPEED WRG/PROBE SHARED RNG will show in the maintenance alert faults.

      1. If the fault message N1 SPEED CH A WRG/PROBE RNG is not active, go to step 23.
      2. If the fault message N1 SPEED CH A WRG/PROBE RNG stays active, continue with next step.

10. Disconnect the EEC connector P1046 and the N1 speed probe connector P1077. Perform a visual inspection of the interface wiring between EEC (P1046) and The N1 speed probe (P1077).
    CAUTION: DO NOT DO ELECTRICAL CHECKS INTO THE ENGINE ELECTRONIC CONTROLLER (EEC). IF YOU DO NOT OBEY THIS INSTRUCTION, DAMAGE TO THE EEC CAN OCCUR.
    NOTE: Look specially for signs of chafing adjacent to clip locations, condition of connector pins and wiring kink or strain.

    1. If system check is not good, repair defective wiring as required and go to step 23.
    2. If system check is good, continue with next step.

11. Perform wiring checks between N1 Speed Probe (P1077) and EEC (P1046).

    1. If wiring checks are not good, repair defective wiring as required and go to step 23.
    2. If wiring checks are good, continue with next step.

12. Perform a check of the insulation resistance of the interface between the EEC and the N1 speed probe as follows:

    From	To	Expected Result	Result
    P1046-45	Ground	>20 megohm
    P1046-25	Ground	>20 megohm

    1. If the fault message N1 SPEED CH B WRG/PROBE RNG stays active, replace the EEC and go to step 23.
    2. If the fault message N1 SPEED WRG/PROBE SHARED RNG was given, continue with next step.

13. Perform the fault isolation procedure for N1 speed probe shared.

    1. If the fault message is not active, go to step 23.
    2. If the N1 speed probe shared or its attached core interface wiring are defective, continue with next step.

14. Disconnect the connector P1077 for the N1 speed probe of channel B.
15. Disconnect the connector P1076 for the N1 speed probe shared.
16. Connect the connector P1077 to the interface receptacle for the N1 speed probe shared.

    1. If the fault message N1 SPEED WRG/PROBE SHARED RNG is not given, go to step 19.
    2. If the fault message N1 SPEED WRG/PROBE SHARED RNG is active, the N1 speed probe for channel B or its attached core interface wiring are defective. No more fault isolation is possible, continue with next step.

17. Replace power plant.

    1. If system checks are good, go to step 23.
    2. If fault remains, continue with next step.

18. Disconnect the connector P1077 from the interface receptacle for the N1 speed probe shared and connect the connector P1076 to the interface receptacle for the N1 speed probe shared.
19. Perform the fault isolation procedure for N1 speed probe shared.

    1. If you find a defective interface, no continuity, or insulation resistance not as specified, repair or replace the defective wiring as required and go to step 23.
    2. If the system checks are good, continue with next step.

20. Connect electrical power to the aircraft.
21. Make sure that EICAS L FADEC FAIL (Caution) does not show on the EICAS display.
22. Remove the electrical power from the aircraft.
23. Close the Cowl and activate the thrust reverser.
24. Do close out.