09/19/19
Message Overview:
Fault Message:
FADEC [OVERSPEED CIRCUIT 1]
Fault Code:
4960250APU
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 ] |
Fault Description:
The Full-Authority Digital Engine-Controller (FADEC) has detected a loss of redundant overspeed protection. The FADEC has detected an internal failure to its overspeed protection circuitry.
NOTE: An asterisk mark (*) in any row above means that the automatic protection shut down on that row is inhibited if the associated fault occurs in flight. The respective CAS message, or an advisory message reading APU FAULT will be displayed in the CAS window and the APU will not shut down automatically in flight. However the pilot may select to shut down the APU manually by placing the APU control switch to OFF.
| Fault | See * below | Description |
|---|---|---|
| FADEC FAILURE | ECU internal failure (CPU, watchdog timer, O/S circuit failure, loss of O/S protection, etc.) | |
| O/SPD | (Hardware/Software) overspeed circuits tripped (at 106%) | |
| LOSS OF SPEED | Both monopoles failed | |
| LOSS OF O/SPD | FADEC overspeed circuit/FCU fuel output solenoid failed | |
| OVERTEMP | * | EGT limit exceeded during i) start ii) on-speed operation |
| FIRE EMERG | * | Fire signal is received by the FADEC |
| REVERSE FLOW | * | T2 temp. limit (176.6°C/350°F) has been exceeded for 5 secs |
| HIGH OIL TEMP | * | Oil temp limit of >148.9°C exceeded for 10 seconds |
| LOW OIL PRESS | * | Oil pressure has fallen below lower limit of 30 psig for 15 seconds, with rpm > 95% |
| LOSS OF EGT DETECTION | * | Both EGT thermocouples have failed (NOTE: In Essential Mode, FADEC programs an EGT of 260°C to maintain the APU running) |
| NO FLAME | EGT rise has not been detected within 17 seconds of fuel solenoid being commanded open by FADEC, or rpm >18% for 5 seconds | |
| NO ACCEL | Acceleration is < 0.05% of the prescheduled rate (normal acceleration is 2.5% per seconds) | |
| SLOW SPEED | Starter timer expired - APU rpm > 5% and less than starter cut out for 30 seconds | |
| UNDER SPEED | * | Speed has reached 100%, then drops below 80% for 5 secs |
| NO CRANK | rpm does not rise above 5% within: a) 2 secs when oil temp is warmer than minus 23°C, or b) 50 secs when oil temp is minus 23°C or lower |
|
| INLET DOOR | Inlet door position indicates closed 30 secs before starter engagement, or 600 msecs. after starter engagement | |
| LOSS OF DC POWER | Loss of 28 VDC power for 200 milliseconds | |
| LOP SW FAIL | * | Oil pressure switch has failed open when rpm is < 7% ( NOTE: This switch is normally closed during prestart BITE) |
| FALLBACK | APU drop below 25% rpm after starter cutout | |
| APU GCU HIGH OIL TEMP | * | APU Generator oil temperature above 215°C |
Possible Causes:
- Auxiliary Power Unit (APU) Full-Authority Digital Engine-Controller (FADEC) (A108)
- Speed Sensor (MT4)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Removal of the Engine Branched Wiring-Harness | AMM 49-12-01-000-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Installation of the Engine Branched Wiring-Harness | AMM 49-12-01-400-801 [ 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 ] |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 [ Global Express ] [ G5000 ] [ Global XRS ] |
Troubleshooting Recommendations:
- Inspect the wiring and connectors to the speed sensor for any damage.
- If system checks are not good, repair or replace defective wiring as required and do close out.
- If system checks are good, continue with next step.
- Inspect the speed sensor for condition and check that the resistance within speed senor as follows:
From To Expected Result Result MT4P1-A MT4P1-B 54.08 - 81.12 Ohms - If system checks are not good, replace speed sensor and do close out.
- If system checks are good, continue with next step.
- Re-rack FADEC and verify connector A108AP1-G11, A108AP1-H11, A108AP1-J11 and A108AP1-K11 for damage or FOD, verify if fault is still present.
- Perform continuity check between APU firewall and the speed sensor connector. The resistance should measure as follows:
From To Expected Result Result P802-13 MT4P1-A <1 ohm P802-14 MT4P1B <1 ohm - If measurements are not good, repair defective wiring as required and do close out.
- If measurements are good, continue with next step.
- Perform wiring check between APU firewall and the APU FADEC connector. The resistance should measure as follows:
From To Expected Result Result J802-13 A108AP1-G11 <3 ohms J802-14 A108AP1-H11 <3 ohms - If measurements are not good, repair defective wiring as required and do close out.
- If measurements are good, continue with next step.
- Replace the APU FADEC.
- Do close out.