08/16/19
Message Overview:
| DDG Reference: | 49-10-01 |
| Pilot Action (QRH): | ABNORM 4-5 |
| System Description: | 49-90-00 |
| Schematic Diagram: | 49-61-00 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Wiring Diagram: | 49-61-01 [ Global Express ] [ G5000 ] [ Global XRS ] |
Fault Description:
Low oil-pressure switch indicates a low oil pressure condition for 15 seconds as reported by the APU FADEC.
Possible Causes:
- Oil Leakage/low Oil Quantity
- Low Oil-Pressure Switch (failed closed)
- Full Authority Digital Engine Controller (FADEC)
- Oil Pump
- Auxiliary Power Unit (APU) Gearbox
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
The Low Pressure Switch is listed on the recommended spares list and is highly suggested as a customer stocked spare.
This message may be preceded with the APU OIL LOW QTY message.
If this message is in conjunction with an "impending oil bypass" or "oil bypass" message trouble shoot these faults first.
Quick Links:
| Quantity Check of the Oil Supply in the APU | AMM 12-14-09-610-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Servicing of the APU Oil Supply | AMM 12-14-09-612-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Removal of the Low Oil Pressure Switch | AMM 49-90-41-000-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Installation of the Low Oil Pressure Switch | AMM 49-90-41-400-801 [ 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 ] |
| Access to CAIMS Active Faults | AMM 45-45-00-970-802 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Removal of the Oil Pump | AMM 49-90-21-000-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Installation of the Oil Pump | AMM 49-90-21-400-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Removal of the APU | AMM 49-10-00-000-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Installation of the APU | AMM 49-10-00-400-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| APU Electrical Harness Wiring Diagram 49-12-00 | WM 49-12-00 [ Global Express ] |
| Wire Repair | SPM 20-12-10 [ Global Express ] [ G5000 ] [ Global XRS ] |
Troubleshooting Recommendations:
- Prior to opening APU access doors, inspect for area oil leaks in and around the APU exhaust duct (on the right side of the aircraft tail).
- Inspect the low oil pressure switch, the oil pump, the gearbox, the APU and APU exhaust (inside APU enclosure) for signs of oil leaks.
- Check the oil quantity in the APU.
- If APU oil level was low, investigate absence of APU OIL LOW QTY message.
- Fix leak. Go to step 11.
- Check CAIMS for additional messages.
- If additional messages found troubleshoot accordingly.
- No additional messages continue.
- Perform wiring check between APU FADEC and the low oil pressure switch (S1P1).
- If wiring faults found, repair go to step 11.
- If wiring checks good continue.
- Replace low oil pressure switch.
NOTE: Switch contacts A-B will open at 40 psig as monitored by the APU FADEC above 95% RPM. - If fault is still present. Attach pressure gauge "T" at switch port. Monitor pressure.
- If oil pressure checks good. Go to step 8.
- If oil pressure is low go to step 9.
- Replace the APU FADEC.
- Go to step 10.
- Replace the oil pump.
- Monitor oil pressure, if good go to step 10.
- If oil pressure still low continue.
- Replace the APU.
- Do close out.