Fault Message:

R CH B AIR DATA COMPUTER T20 RNG MA

Fault Code:

7327517RBR

Associated CAS:

None

This message shows when the T20 signal of Total Air Temperature (TAT) sent by the Micro Air-Data Computers (MADCs) is not within operational parameters. The signal is sent to channel B of the Engine Electronic Controller (EEC) by the Micro Air-Data Computer (MADC) 1 or MADC 2. These circuits are continuously monitored by the Full-Authority Digital Engine-Controller (FADEC).

• Micro Air-Data Computer (MADC) 1 (A27)
• Micro Air-Data Computer (MADC) 2 (A28)
• P20/T20 Probe
• Right Engine Electronic Controller (EEC)

Advisory Wire/Service Bulletin:

• AW700-45-0065 - CAIMS Nuisance Fault Messages

Forum Articles/Infoservice/Newsletter: None

1. Check if the fault message shows only on ground, review AW700-45-0065 - CAIMS Nuisance Fault Messages.
2. Check if the fault message happens during flight, use the Flight Test Data Sheet table to record all 3 TAT readings at various altitudes. Once all the data is recorded, compare temperature readings between all three.

   1. If one of the TAT probes is generally warmer than the other two, especially at higher altitudes, replace affected probe and do close out.
   2. If all reading values are the same on all three TAT probes throughout the flight, continue with next step.

3. Swap Right EEC with Left EEC and monitor for failure at the next flight. Is the fault still present?

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

4. Swap MADC 1 with MADC 3 and monitor for failure at the next flight. Is the fault still present?

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

5. Replace MADC 2.
6. Do close out.