03/28/22
Message Overview:
Message Name:
NO ATS-1 BUS INPUT
Message Code:
B3-681829
Associated CAS:
| Reporting LRU: | IOC 1 |
| Effectivity: | Post SB350-22-002 Aircraft 20937 and Subs |
| System Description: | 22-30-00 - Auto Throttle System (ATS) |
| Schematic Diagram: | 22-30-00-801 - Auto Throttle System (ATS) 31-45-00-101 - Integrated-Avionics Processor System (IAPS) |
| Wiring Diagram: | 22-30-00-801 - Auto Throttle System (ATS) 31-45-11-03 - INPUT/OUTPUT CONCENTRATOR UNIT (IOC) LEFT 31-45-13-03 - INPUT/OUTPUT CONCENTRATOR UNIT (IOC) RIGHT |
Message Description:
The ATS-1 bus is reported absent by the left Input/Output Concentrator (IOC).
Possible Causes:
- Autothrottle (AT) Computer (A252)
- IAPS Input/Output Concentrator (IOC) card
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
NOTE: Review the Auto Throttle "AT Diagnostic Information", to find details about the MDC Data Reader Labels & bits.
NOTE: Bombardier recommends referencing the elements one (1) through eleven(11) of the "Wiring & Connections" Troubleshooting Tips document. The intent of the document is to ensure the Maintenance Technician has the information needed to perform a comprehensive check of an aircraft system wiring circuit, while also doing checks found in the From - To tables called out in the Troubleshooting Recommendations element.
| From | To | Expected Results | Results |
|---|---|---|---|
| XXXX-XX | XXXX-XX | Continuity |
Quick Links:
| Removal of the Auto Throttle Computer | AMM 22-30-01-000-801 |
| Installation of the Auto Throttle Computer | AMM 22-30-01-400-801 |
| Removal of the Input/Output Concentrator Unit (IOC) | AMM 31-45-05-000-801 |
| Installation of the Input/Output Concentrator Unit (IOC) | AMM 31-45-05-400-801 |
| Operational Test of the Input/Output Concentrator Unit (IOC) | AMM 31-45-05-710-801 |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Make sure the Autothrottle (AT) Computer Circuit Breaker (CB2-A8) is set to IN.
- If the CB was set to OUT, investigate the reason and set it back to IN if possible, confirm faults related to the AT system have cleared and do close out.
- If the CB was already set to IN, continue with next step.
- Remove the AT computer (A252). Do wire check as follows:
NOTE: Refer to the "Wiring & Connections" document found in the Troubleshooting Tips element of this page.
From To Expected Result Result A252P1-30 Ground 28 VDC A252P1-22 Ground Continuity A252P1-9 Ground Continuity - If results are as per table above, continue with next step.
- If 28 VDC or ground is missing, perform wiring checks and repair as required.
- Interchange the left Input/Output Concentrator (IOC) card in the IAPS with the right IOC card. Is the fault still present on the same side?
- If YES, return the IOC cards to their original position and continue with next step.
- If NO, replace defective IOC card.
- Remove the AT computer (A252) and disconnect Integrated Avionics Processing System (IAPS) connector A4P3. Do a wire check between the AT Computer (A252) and the IAPS (A4) as follows:
NOTE: Refer to the "Wiring & Connections" document found in the Troubleshooting Tips element of this page.
From To Result A252P1-18 A4P3-11 A252P1-19 A4P3-12 - If wiring defects are found, repair defective wiring as required and do close out.
- If no defects are found, continue with next step.
- Replace the AT Computer (A252)
- Do close out.