Left System Failure - Loss of Pressure Only
This is a work in progress
The left HYD pressure is less than or equal to 2349 PSI or greater than or equal to 3449 PSI.
- Aircraft Operating Envelope: Speed reduced to 285 KCAS / 0.90M maximum.
- Left Thrust Reverser: Inoperative.
- Midboard Spoilers: Inoperative.
- Airspeed . . . 285 KCAS / 0.90M maximum
- Hydraulic Synoptic / Quantity . . . Check
- If a loss of L SYS fluid is suspected or has occurred:
- Refer to 04-15-20, Left Hydraulic System (L SYS) Failure - Loss of Pressure and Fluid.
- If the hydraulic failure occurred within 2 hours of takeoff:
- Airplane Land at nearest suitable airport no more than 4 hours after the hydraulic failure, then go to Step 6
- If the hydraulic failure did not occur within 2 hours of takeoff:
- Airplane . . . Land as soon as practicable
- Once the landing airport has been determined:
- PTU . . . NOT ARMED / OFF
- PTU . . . ARMED / ON
- AUX PUMP ARMED / OFF
- FLAPS . . . 20°
- LANDING GEAR / Lights . . . DOWN / 3 green
- FLAPS . . . 39°
- Before Landing Checklist . . . Perform
- Approximately 1 minute prior to landing:
- AUX PUMP . . . ARMED / ON
- Brakes / Steering . . . As required to maintain directional control
- Thrust Reverser (Right) . . . As required
With the landing gear in the up position the Left Hydraulic System reservoir will show approximately one gallon of fluid with a complete loss of Left Hydraulic System fluid. When the gear is selected down, the Left Hydraulic System reservoir will indicate empty.
IF A HYDRAULIC SYSTEM FAILURE OCCURS WITHIN 2 HOURS AFTER TAKEOFF, LAND AT THE NEAREST SUITABLE AIRPORT NO MORE THAN 4 HOURS AFTER THE FAILURE OCCURRED. CONTINUING FLIGHT IN EXCESS OF 4 HOURS COULD RESULT IN A FLIGHT CONTROL SURFACE FAILURE, AND A LOSS OF AIRCRAFT CONTROL.
I am told that this is because the hydraulic fluid gets hot during takeoff and takes four hours to cool. If it has less than that and is just sitting stagnant in the lines, it is apt to rupture a seam or fitting and leak.
Hydraulic fluid temperature has stabilized, and flight control surface failure is not a concern.
With the auxiliary hydraulic pump armed, the pump will automatically activate if required to assist the PTU in providing demanded pressure and to provide pressure for landing gear and flaps.
For landing gear and flap operation, operate one system at a time allowing completion of cycle before operating the next system.
Gulfstream GVII-G500 Airplane Flight Manual, Revision 1, August 31, 2018