08/12/19
Message Overview:
Fault Message:
APU SHUT DOWN-LOSS OVSP PROTECTION
Fault Code:
4960129APU
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: | 49-61-01 [ Global Express ] [ G5000 ] [ Global XRS ] |
Fault Description:
The Full-Authority Digital Engine-Controller (FADEC) cannot supply protection against an over speed condition due to failures of any combination of speed sensors circuits and/or FADEC and/or fuel solenoid that results in a loss of primary and secondary over speed protection. In this condition, the FADEC will prevent a start or cause an Auxiliary Power Unit (APU) shutdown.
| 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) startii) 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 seconds |
| 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 pre-scheduled 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 seconds |
| NO CRANK | RPM does not rise above 5% within:a) 2 seconds when oil temp is warmer than minus 23 °C, orb) 50 seconds when oil temp is minus 23°C or lower. | |
| INLET DOOR | Inlet door position indicates closed 30 seconds before starter engagement, or 600 milliseconds 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 |
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.
Possible Causes:
- Auxiliary Power Unit (APU) Full-Authority Digital Engine-Controller (FADEC) (A108)
- Fuel Control Unit (FCU) (A3)
- 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 Fuel Control Unit | AMM 49-30-01-000-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Installation of the Fuel Control Unit | AMM 49-30-01-400-801 [ 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:
- Examine the APU wiring harness for bare wiring, kinks, worn areas and other damage.
- If damages are found, repair as required and do close out.
- If damages are not found, continue with next step.
- Re-rack FADEC and verify both the tray and FADEC connectors for damage or FOD.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Disconnect the A3P1 connector from the FCU (A3) and examine the FCU (A3) receptacle for contamination and damage.
- Perform a continuity check within FCU connectors (A3P1) receptacle as follows:
From To Expected Result Result A3P1-C A3P1-D 31 Ω - 37 Ω - If there is no continuity, repair defective wiring as required and do close out.
- If there is continuity, continue with next step.
- Perform a continuity check within FCU connectors (A3P1) receptacle as follows:
From To Expected Result Result A3P1-A A3P1-B 15 Ω - 30 Ω - If there is no continuity, repair defective wiring as required and do close out.
- If there is continuity, continue with next step.
- Disconnect the MT4P1 connector from the speed sensor (MT4) and examine the speed sensor (MT4) receptacle for contamination and damage.
- Perform a continuity check within speed sensor connectors (MT4P1) receptacle as follows:
From To Expected Result Result MT4P1-A MT4P1-B 15 Ω - 40 Ω - If there is no continuity, repair defective wiring as required and do close out.
- If there is continuity, continue with next step.
- Perform a continuity check within speed sensor connectors (MT4P1) receptacle as follows:
From To Expected Result Result MT4P1-D MT4P1-E 15 Ω - 40 Ω - If there is no continuity, repair defective wiring as required and do close out.
- If there is continuity, continue with next step.
- Disconnect the P802 connector at the APU fire wall interface (FS1046LHS) and perform a continuity check between the APU connector (P802) and speed sensor connector (MT4P1) as follows:
From To Expected Result Result P802-13 MT4P1-A <1 Ω P802-14 MT4P1-B <1 Ω P802-39 MT4P1-D <1 Ω P802-40 MT4P1-E <1 Ω - If there is no continuity, repair defective wiring as required and do close out.
- If there is continuity, continue with next step.
- Perform a continuity check between the APU connector (P802) and FCU connector (A3P1) as follows:
From To Expected Result Result P802-17 A3P1-A <1 Ω P802-18 A3P1-B <1 Ω P802-41 A3P1-C <1 Ω P802-42 A3P1-D <1 Ω - If there is no continuity, repair defective wiring as required and do close out.
- If there is continuity, continue with next step.
- Remove the FADEC (A108) and Disconnect the J802 connector at the APU firewall interface (FS1046 LHS).
- Perform a continuity check between A/C wiring harness connector (J802) and FADEC (A108AP1) as follows:
From To Expected Result Result J802-13 A108AP1-G11 <3 Ω J802-14 A108AP1-H11 <3 Ω J802-39 A108AP1-J11 <3 Ω J802-40 A108AP1-K11 <3 Ω - If there is no continuity, repair defective wiring as required and do close out.
- If there is continuity, continue with next step.
- Perform a continuity check between the A/C wiring harness connector (J803) and FADEC connector (A108AP1) as follows:
From To Expected Result Result J803-41 A108AP1-F2 <3 Ω J803-42 A108AP1-G2 <3 Ω J803-17 A108BP1-A1 <3 Ω J803-18 A108BP1-B1 <3 Ω - If there is no continuity, repair defective wiring as required and do close out.
- If there is continuity, continue with next step.
- Replace FADEC.
- Do close out.