Narrative:

We departed ZZZ airport runway 24 uneventfully enroute to our planned destination of ZZZ1 with 2 passengers on board. During climb at approximately 12;000 ft; we observed a hydraulic 2 low pressure amber annunciator illuminate for approximately 1 minute; and then go out. Hydraulic pressure gauge indicated 3;000 psi (normal) at that time. I was pilot flying in the right seat; assumed ATC radio duties and my partner ran the abnormal checklist. The abnormal checklist called for no inflight action. We advised the acp on duty via afis message; and continued on. As the flight progressed in cruise we noticed the hydraulic pressure began to fluctuate between 3;000 psi and the minimum pressure maintaining valve indication of 2;300 psi. The hydraulic 2 low pressure annunciator illuminated again; followed by a periodic hydraulic 1 low pressure indication; which agreed with the pressure gauge indications we were seeing. Acp on duty was then contacted by flight phone and advised of the situation; who subsequently advised maintenance control. My partner and I discussed our options; and reviewed the complete main hydraulic system failure abnormal checklist of the aircraft in case its use became necessary. I suggested that I transfer control of the aircraft to my partner in the left seat as to avoid transfer of controls on the runway; and we did so at that time. Due to the number of systems that are affected by a main hydraulic system failure (gear; flaps; steering; brakes; flaps; air brakes; thrust reverse); we declared an emergency with center approximately 150 miles from ZZZ1. We advised ATC that we would be unable to taxi and ask the crash fire rescue equipment be standing by; and to notify FBO that we would need a tug to tow our aircraft from the runway. Approximately 35 miles from ZZZ1; we began to slow and configure the aircraft in case an alternate gear/flaps extension became necessary. Observing the hydraulic pressure gauge; we had occasional moments of 2;800 psi and higher. With that 2;800 psi indication; my partner called for flaps 15 degrees; which extended normally. Gear down was selected shortly thereafter. It took approximately 20 seconds for the main gear to indicate down and locked; standby gear indications confirmed gear down. At approximately 15 miles from ZZZ1 we were cleared for the ILS runway 28L approach and selected the remainder of our landing flaps; which extended normally. Both hydraulic #1 and hydraulic #2 low pressure were illuminated at that time; and hydraulic pressure was varying at that point between 2;300-2;800 psi. After a normal touchdown; my partner selected lift dump and thrust reverse; which deployed normally. Steady brake pressure was applied; with an apparent loss of steering at approximately 60-80 KTS. We stopped on the runway and performed after landing and shutdown with APU checklists. Hydraulic pressure at that time indicated 1;800 psi and I observed that the parking brake 'left and right' white lights were illuminated. We observed that the lift dump/flaps and air brakes did not retract; and the left thrust reverse 'unlock' light was illuminated. Crash fire rescue was notified by radio of the left thrust reverse unlock light and that we would not coordinate with personnel on the ground. My partner performed a postflight walkaround on the runway; and pinned both the main and nose gear. Passengers were offered a ride on an airport operations vehicle; however; after some discussion we elected to keep them with us until arrival at our facilities (night; etc). In accordance with maintenance personnel who arrived to tow our aircraft; we determined the aircraft was safe to be towed; and we were then repositioned to the ramp. Passengers were met at the aircraft by owner's service representatives; and we secured the aircraft.

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Original NASA ASRS Text

Title: An HS 125-800 XP made an emergency landing after both HYD 1 and 2 had abnormal pressure indications. After landing the aircraft was towed to the ramp because hydraulic pressure did not allow normal systems operations.

Narrative: We departed ZZZ Airport Runway 24 uneventfully enroute to our planned destination of ZZZ1 with 2 passengers on board. During climb at approximately 12;000 FT; we observed a Hydraulic 2 Low Pressure amber annunciator illuminate for approximately 1 minute; and then go out. Hydraulic pressure gauge indicated 3;000 PSI (normal) at that time. I was Pilot Flying in the right seat; assumed ATC radio duties and my partner ran the abnormal checklist. The abnormal checklist called for no inflight action. We advised the ACP on duty via AFIS message; and continued on. As the flight progressed in cruise we noticed the hydraulic pressure began to fluctuate between 3;000 PSI and the minimum pressure maintaining valve indication of 2;300 PSI. The Hydraulic 2 Low Pressure annunciator illuminated again; followed by a periodic Hydraulic 1 Low Pressure indication; which agreed with the pressure gauge indications we were seeing. ACP on duty was then contacted by flight phone and advised of the situation; who subsequently advised Maintenance Control. My partner and I discussed our options; and reviewed the complete Main Hydraulic System Failure abnormal checklist of the aircraft in case its use became necessary. I suggested that I transfer control of the aircraft to my partner in the left seat as to avoid transfer of controls on the runway; and we did so at that time. Due to the number of systems that are affected by a main hydraulic system failure (gear; flaps; steering; brakes; flaps; air brakes; thrust reverse); we declared an emergency with Center approximately 150 miles from ZZZ1. We advised ATC that we would be unable to taxi and ask the Crash Fire Rescue equipment be standing by; and to notify FBO that we would need a tug to tow our aircraft from the runway. Approximately 35 miles from ZZZ1; we began to slow and configure the aircraft in case an alternate gear/flaps extension became necessary. Observing the hydraulic pressure gauge; we had occasional moments of 2;800 PSI and higher. With that 2;800 PSI indication; my partner called for flaps 15 degrees; which extended normally. Gear down was selected shortly thereafter. It took approximately 20 seconds for the main gear to indicate down and locked; standby gear indications confirmed gear down. At approximately 15 miles from ZZZ1 we were cleared for the ILS Runway 28L approach and selected the remainder of our landing flaps; which extended normally. Both Hydraulic #1 and Hydraulic #2 Low Pressure were illuminated at that time; and hydraulic pressure was varying at that point between 2;300-2;800 PSI. After a normal touchdown; my partner selected lift dump and thrust reverse; which deployed normally. Steady brake pressure was applied; with an apparent loss of steering at approximately 60-80 KTS. We stopped on the runway and performed After Landing and Shutdown With APU checklists. Hydraulic pressure at that time indicated 1;800 PSI and I observed that the parking brake 'left and right' white lights were illuminated. We observed that the lift dump/flaps and air brakes did not retract; and the left thrust reverse 'unlock' light was illuminated. Crash Fire Rescue was notified by radio of the Left Thrust Reverse Unlock light and that we would not coordinate with personnel on the ground. My partner performed a postflight walkaround on the runway; and pinned both the main and nose gear. Passengers were offered a ride on an airport operations vehicle; however; after some discussion we elected to keep them with us until arrival at our facilities (night; etc). In accordance with Maintenance personnel who arrived to tow our aircraft; we determined the aircraft was safe to be towed; and we were then repositioned to the ramp. Passengers were met at the aircraft by Owner's service representatives; and we secured the aircraft.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.