Message Name:

TRU 1 FAN FAILED

Message Code:

2460460DCP

Associated CAS:

ELEC SYS FAULT
(Advisory)

The Transformer Rectifier Unit (TRU) 1 Fan Speed Sensor is low or no Fan output to the DC Power Center (DCPC).

• DC Power Center (DCPC) (A63)
• DC Power Quality Monitor (DCPQM) Card 1
• Transformer Rectifier Unit (TRU) 1 (A73)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

NOTE: The TRU 1 fan fail will show on the DC synoptic page, as the TRU 1 outline will be amber and the TRU output voltage is approximately 28 VDC.
NOTE: If the TRU voltage displayed on the DC synoptic page is different than 28 VDC, check that all three 115 VAC input phases are present. A missing phase could result in the fan not spinning.
NOTE: Verify C/B status on both pilot and copilot EMS CDUs. This Fault Message will post if either of the following circuit breaker or Smart Contactor status is OUT or Tripped.

1. Check status of AC 1 FEED on EMS CDU, the AC 1 Feed being out or tripped can drive multiple CAS to post.
   BUS > AC 1 > AC 1 FEED.

   1. If AC 1 FEED CB is IN go to step 3.
   2. If AC 1 FEED CB is OUT, set to IN.
      

      AC 1 FEED

      CB	SYSTEM	PHASE	CAS
      CB-G6	ESS TRU 1	3	AC BUS 1 FAIL (Caution)
      CB-G3	EVS FAIRING HEAT	3	EVS HEAT FAIL (Caution)
      CB-G9	SLAT/FLAP PWR 1	3	SLAT-FLAP HALFSPD (Advisory)
      CB-H5	EVS WINDOW HEAT	1	EVS HEAT FAIL (Caution)
      CB-H6	A/T CTLR	1	A/T 1 FAIL (Advisory) A/T 2 FAIL (Advisory)
      CB-H7	PITOT 1 HT A	1	PITOT 1 HT FAIL (Caution)
      CB-H8	R ICE DETECTOR	1	ICE DETECTOR FAULT (Advisory)
      CB-H9	R AOA HEAT A	1	R AOA HEAT FAIL (Caution)
      CB-H10	L WSHLD HEAT 1	1	L WSHLD HEAT FAIL (Caution)
      CB-H11	L WSHLD HEAT 2	1	L WSHLD HEAT FAIL (Caution)
      CB-G12	TRU BAY FAN	3	ELEC SYS FAULT (Advisory) 2460460DCP TRU 1 FAN FAILED
      CB-B6	STAB TRIM CH1	3	STAB CH 1 FAIL (Advisory)

2. Did the CAIMS Fault & CAS messages clear after setting AC 1 FEED CB to IN.

   1. If YES, do close out.
   2. If NO, go to next step.
   3. Get Access to the FWD bay to check for the airflow of the TRU 1 and confirm if the fan is rotating or not.

      1. If the fan is not rotating, replace TRU 1 and do close out.
      2. If the fan is rotating, continue with next step.

   4. Interchange TRU 1 with another TRU. Is the fault still present?

      1. If YES, continue with next step.
      2. If NO, replace defective TRU.

   5. Disconnect TRU 1 connector A73P1 and DCPC connector A63P1. Perform a continuity check as follows:

      From	To	Result
      A73P1-D	Ground

      1. If there is continuity, repair defective wiring as required and do close out.
      2. If there is no continuity, continue with next step.

   6. Perform a continuity check as follows:

      From	To	Result
      A73P1-D	A63P1-A

      1. If there is no continuity, repair defective wiring as required and do close out.
      2. If there is continuity, continue with next step.

   7. Access the DCPC Logic assembly and remove the DCPQM 1 card. Perform a continuity check as follows:

      From	To	Result
      A63P1-A	Ground

      1. If there is continuity, go to step 8.
      2. If there is no continuity, continue with next step.

   8. Perform a continuity check as follows:

      From	To	Result
      A63P1-A	P121A-10

      1. If there is no continuity, go to step 8.
      2. If there is continuity, continue with next step.

   9. Replace the DCPQM 1 card.

      1. If system checks are good, do close out.
      2. If fault remains, continue with next step.

   10. Replace DCPC.
   11. Do close out.