HYD 3 LO PRESS

07/23/19

Message Overview:

HYD 3 LO PRESS
(Caution)

DDG Reference:	None
Pilot Action (QRH):	ABNORM 10-8
System Description:	29-30-00
Schematic Diagram:	29-13-00 [ Global Express ] [ G5000 ] [ Global XRS ]
Wiring Diagram:	29-00-05 [ Global Express ] [ G5000 ] [ Global XRS ]

Fault Description:

No. 3 hydraulic-system is less than 1800 psi.

Possible Causes:

The hydraulic System Filter Manifold Pressure Transducer
Data Acquisition Unit (DAU) 3
AC Hydraulic Pump 3A
AC Hydraulic Pump 3B
Hydraulic quantity
Hydraulic Fluid Filter Elements
Hydraulic System Pressure Relief Valve (Filter Manifold)
Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Quantity Check of the Hydraulic Reservoir Fluid	AMM 12-12-00-610-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Removal of Data Acquisition Units (DAU)	AMM 31-42-01-000-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Installation of Data Acquisition Units (DAU)	AMM 31-42-01-400-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Removal of No. 3 Hydraulic System Filter Manifold	AMM 29-13-05-000-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Installation of No.3 Hydraulic System Filter Manifold	AMM 29-13-05-400-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Removal of No. 3 Return Filter Element	AMM 29-13-13-000-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Installation of No. 3 Return Filter Element	AMM 29-13-13-400-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Removal of No. 3 Press Filter Element	AMM 29-13-09-000-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Installation of No.3 Press Filter Element	AMM 29-13-09-400-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Removal of No. 3 Case Drain Filter Element	AMM 29-13-17-000-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Installation of No. 3 Case Drain Filter Element	AMM 29-13-17-400-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Removal of No.3 ACMP	AMM 29-13-01-000-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Installation of No.3 ACMP	AMM 29-13-01-400-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Removal of Hydraulic Temperature Transducers	AMM 29-33-01-000-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Installation of Hydraulic Temperature Transducers	AMM 29-33-01-400-801 [ Global Express ] [ G5000 ] [ Global XRS ]
Wire Repair	SPM 20-12-10 [ Global Express ] [ G5000 ] [ Global XRS ]

Troubleshooting Recommendations:

Ensure system is properly serviced.
1. If low quantity found, service system and recheck system. If system checks are good, do a close out.
2. If quantity is good, continue with next step.
Operate 3A and 3B Hydraulic ACMPs independently. Confirm pump operation on Hydraulic Synoptic page.
1. If pump(s) fail to operate, replace applicable pump and retest. If system checks are good, do a close out.
2. If fault remains, continue with next step.
Inspect system filter DPIs.
1. If DPIs are tripped, replace associated filter(s) and recheck system. If system checks are good, do a close out.
2. If DPIs are good, continue.
Swap Hyd System No. 3 Transducer (MT146) and Hyd System No. 1 Transducer (MT140).
1. If system checks are good, do a close out.
2. If fault remains, continue with next step.
Swap DAUs.
1. If system checks are good, do a close out.
2. If fault remains, continue with next step.
Perform wiring check between No. 3 filter manifold transducer (MT146), DAU 3 and SPDA 3. Confirm 28 VDC input from SPDA 3 to transducer.
1. If wiring fault found / repaired and message clears, do a close out.
2. If no voltage is found, SWAP SPDA 3 and SPDA 2.
3. If system checks are good, do a close out.
Replace the No. 3 Hydraulic System Filters.
1. If system checks are good, do a close out.
2. If fault remains, continue with next step.
Swap Hydraulic System Filter Manifolds 3 and 2.
1. If system checks are good, do a close out.
2. If fault remains, continue with next step.
Accomplish Hydraulic System No. 3 Internal Leakage Check.
Do close out.