02/16/21
Message Overview:
Message Name:
SPEED SENSOR [THRESHOLD SIG CKT 2]
Message Code:
4960271APU
Associated CAS:
| Reporting LRU: | Full-Authority Digital Engine-Controller (FADEC) |
| System Description: | 49-60-00 |
| Schematic Diagram: | 49-61-00 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Wiring Diagram: | 49-12-01 [ Global Express ] [ G5000 ] [ Global XRS ] 49-61-01 [ Global Express ] [ G5000 ] [ Global XRS ] |
Message Description:
Full Authority Digital Engine Controller (FADEC) detected a low signal amplitude for Speed Sensor CKT2.
Possible Causes:
- Auxiliary Power Unit (APU) Full-Authority Digital Engine-Controller (FADEC) (A108)
- Speed Senor (MT4)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Access to Active Faults | AMM 45-45-00-970-802 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Access to Stored Faults | AMM 45-45-00-970-803 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Removal of the Full-Authority Digital Engine-Controller (FADEC) | AMM 49-61-01-000-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Installation of the Full-Authority Digital Engine-Controller (FADEC) | AMM 49-61-01-400-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Removal of the Speed Sensor | AMM 49-61-17-000-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Installation of the Speed Sensor | AMM 49-61-17-400-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Stowage of Electrical Wiring - Maintenance Practices - ALL | SPM 20-12-05-02 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 [ Global Express ] [ G5000 ] [ Global XRS ] |
Troubleshooting Recommendations:
- Get access to the CAIMS to view the above fault message and other APU related faults.
- If fault message is present, troubleshoot them first and continue with next step.
- If fault message is not present, continue with next step.
- Re-rack APU FADEC and verify condition of APU FADEC connector, as well as APU mounting tray connectors for damage.
- If there is a damage, repair as required and do close out.
- If there is no damage, continue with next step.
- Perform a continuity check on Speed Sensor receptacle (MT4) using an ohmmeter as follows:
From To Expected Result Result MT4P1-D MT4P1-E 54.08-81.12 ohms - If resistance is out of range, go to step 7.
- If resistance is within range and fault indication remains, continue with next step.
- Perform wiring checks between APU FADEC connector (A108AP1) and the speed sensor 2 connector (MT4P1) as follow:
From To Result A108AP1-J11 MT4P1-D A108AP1-K11 MT4P1-E - If wiring checks are not good, repair defective wiring as required and do close out.
- If wiring checks are good, continue with next step.
- Perform wiring checks between Speed Sensor 1 (MT4P1) connector and connector on APU firewall as follow:
From To Result MT4P1-A J802-13 MT4P1-B J802-14 - If wiring checks are not good, repair defective wiring as required and do close out.
- If wiring checks are good, continue with next step.
- Perform wiring checks between P802 connector on APU firewall and FADEC (A108AP1) as follow:
From To Result P802-39 A108AP1-J11 P802-40 A108AP1-K11 - If wiring checks are not good, repair defective wiring as required and do close out.
- If wiring checks are good, continue with next step.
- Replace Speed Sensor.
- If system checks are good, do close out.
- If fault remains, continue to next step.
- Replace FADEC.
- Do close out.