02/02/21
Message Overview:
Message Description:
Both channels of the COCKPIT DUCT TEMPERATURE SENSOR are detected failed. Check for the sensor failure.
Possible Causes:
- Cockpit Duct Temperature Sensor (MT35)
- Integrated Air System (IAS) Controller(IASC1) (A55)
- Integrated Air System (IAS) Controller(IASC2) (A56)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Removal of the Integrated Air System (IAS) Controller | AMM 21-31-01-000-801 |
| Installation of the Integrated Air System (IAS) Controller | AMM 21-31-01-400-801 |
| Removal of the Compressor Discharge Temperature-Sensor | AMM 21-52-17-000-801 |
| Installation of the Compressor Discharge Temperature-Sensor | AMM 21-52-17-400-801 |
| Standard Practices - Replace Wiring | SPM 20-12-00-02 |
| Standard Practices - Continuity Test | SPM 20-12-01-05 |
| Standard Practices - Repair Wiring | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Disconnect connector MT35P1. Check continuity between pins 1 to 3 (channel A) and 4 to 5 (channel b) on the Cockpit Temp Sensor. Ref chart for resistance values.
- Reconnect MT35P1 and gain access to IASC #1.
- Disconnect A55P1 and check resistance between pins 28 and 29. Compare to readings recorded between pins 1 and 3 of step 1. If resistance is substantially higher verify wiring between the IASC #1 and DTS.
- Disconnect A56P1 and check resistance between pins 28 and 29. Compare to readings recorded between pins 4 and 5 of step 1. If resistance is substantially higher verify wiring between the IASC #2 and Compressor Discharge Temperature Sensor.
- If the DTS is checking normal and fault still exists, recommend swapping IASCs for further troubleshooting.
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