02/06/26
Message Overview:
Message Name:
AUX HYDRAULIC QTY INDICATION ERRONEOUS
| Identifier: | 292OBS001 |
| Effectivity: | AIRCRAFT 20501 - 20999 |
| System: | Hydraulics |
| System Description: | 29-30-00 - Indicating |
| Schematic Diagram: | 29-12-00 - Left and Right Hydraulic Systems |
| Wiring Diagram: | 29-31-01-1 - Hydraulic Pressure Transducer (LHS) 20501 to 20886, 20888 to 20890, 20896 to 20898 29-31-01-2 - Hydraulic Pressure Transducer (LHS) 20887, 20891 to 20895, 20899 and Subs 29-31-03-1 - Hydraulic Pressure Transducer (RHS) 20501 to 20886, 20888 to 20890, 20896 to 20898 29-31-03-2 - Hydraulic Pressure Transducer (RHS) 20887, 20891 to 20895, 20899 and Subs |
Message Description:
The Auxiliary (AUX) Hydraulic (HYD) Quantity (QTY) indication on the EICAS does not reflect the actual QTY in the HYD fluid reservoir or is dashed out.
Possible Causes:
- Auxiliary Hydraulic Reservoir Quantity Transducer (MT140)
- Remote Data Concentrator (RDC) (A13)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Full Throttle Blog/Forum Articles/Infoservice/Newsletter: None
Flight Operation Notifications Manual (FONM): None
Quick Links:
| General Setup for Maintenance | |
|---|---|
| Standard Aircraft Configuration for Maintenance | AMM 12-00-00-867-803 |
| Connect Electrical Power to the Aircraft | AMM 24-00-00-861-801 |
| Remove Electrical Power from the Aircraft | AMM 24-00-00-861-802 |
| Electrical/Electronic Safety Precautions | AMM 24-00-00-910-801 |
| Electrostatic Discharge Safety Precautions | AMM 24-00-00-910-802 |
| Maintenance Tasks | |
| Hydraulic Safety Precautions | AMM 29-00-00-910-801 |
| Hydraulic Technical Precautions | AMM 29-00-00-910-802 |
| Draining of the Auxiliary Hydraulic System Reservoir | AMM 29-20-00-680-801 |
| Bleeding of the Auxiliary Hydraulic System | AMM 29-20-00-870-801 |
| Removal of the Bleed Relief Valve | AMM 29-21-21-000-802 |
| Installation of the Bleed Relief Valve | AMM 29-21-21-400-802 |
| Removal of the Visual Quantity Indicator | AMM 29-21-21-000-803 |
| Installation of the Visual Quantity Indicator | AMM 29-21-21-400-803 |
Troubleshooting Recommendations:
- On the EICAS Auxiliary (AUX) Hydraulic (HYD) Quantity (QTY) display, is there a QTY value displayed or are dashes displayed.
- If a QTY value is displayed, continue with next step.
- If dashes are displayed, go to step 3.
- Access and disconnect the AUX HYD Reservoir QTY transducer connector (MT140P1). Are dashes now displayed on the EICAS instead of a QTY value?
- If YES, replace the QTY transducer (MT140) and do close out.
- If NO, continue with next step.
- Perform a wiring check between the AUX HYD QTY Transducer and the Remote Data Concentrator (RDC) as follows:
From To Result MT140P1-A A13DP1-5J MT140P1-C A13DP1-2J MT140P1-B A13DP1-2K - 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 AUX HYD QTY Transducer (MT140). Is the fault still present.
- If YES, replace the RDC and do close out.
- If NO, continue with next step.
- Do close out.