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(WARNING)
RED MESSAGE (CAUTION)
AMBER MESSAGE (ADVISORY)
CYAN MESSAGE (STATUS)
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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02/02/21

Message Overview:

Message Name:

CH A FAULT
(Service Message)

Message Code:

B3-006826

Associated CAS:

None

Reporting LRU: HOT AIR T SNSR
System Description: 21-61-00
Schematic Diagram: 21-61-00
Wiring Diagram: 21-61-29

Message Description:

Channel A of the Hot Air Temperature Sensor are detected failed. Check for sensor failure.

Possible Causes:

  • Hot Air Temperature Sensor (HATS) (MT27)
  • Integrated Air System Controller (IASC1) (A55)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Removal of the HATS AMM 21-61-29-000-801
Installation of the HATS AMM 21-61-29-400-801
Operational Test of the Bleed Air System AMM 36-11-00-710-801
Standard Practices - Replace Wiring SPM 20-12-00-02
Standard Practices - Wire Repair SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Reset the PRESS 1 / PACK circuit breaker CB1-D14 and the L WING / BLD LK circuit breaker CB1-E10.

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

  2. Check resistance of Hot Air Temperature Sensor MT27 between pins 1 and 3.

    1. If resistance is within tolerance, go to step 4.
    2. If resistance is out of tolerance, continue with next step.

      Temp in °C Temp in °F Resistance in Ω
      -65 -85 148.4
      -60 -75 152.4
      -50 -58 160.4
      -40 -40 168.4
      -30 -22 176.3
      -20 -4 184.3
      -10 14 192.2
      0.0 32 200.0
      10 50 207.8
      20 68 215.6
      30 86 223.36
      40 104 231.1
      50 122 238.8
      60 140 246.5
      70 158 254.0
      Temp in °C Temp in °F Resistance in Ω
      80 176 261.8
      90 194 269.4
      100 212 277.0
      110 230 284.6
      120 248 292.1
      130 266 299.6
      140 284 307.1
      150 302 314.6
      160 320 322.0
      170 338 329.4
      180 356 336.8
      190 374 344.2
      200 392 351.5
      210 410 258.9
      220 428 366.1
      Temp in °C Temp in °F Resistance in Ω
      230 446 373.4
      240 464 380.7
      250 482 387.9
      260 500 395.1
      270 518 402.3
      280 536 409.4
      290 554 416.5
      300 572 423.6
      310 590 430.7
      320 608 437.8
      330 626 444.8
      340 644 451.8
      350 662 458.8
      360 680 465.8
      370 698 472.7

  3. Replace HATS sensor, (or swapwith Pack Inlet Temperature Sensor MT25).

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

  4. DoWiring & Connectionswiring check between IASC1 A55P3 (pins 17 & 18) and HATS MT27 (pins 1 & 3). Repair as required.

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

  5. SwapIASCs.
  6. Do close out.

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