Narrative:

At approximately after completing all checklists including the after start checklists we contacted ground for taxi. (Flight #X to white plains, ny (hpn)). It was then that I (PF - captain) noticed that the no #2 hydraulic quantity had dropped below dispatch minimums (3.0 qts) and was continuing to decrease at a rapid rate. We immediately taxied back to gate. Maintenance in baltimore, md (bwi) worked on the aircraft (actually it was one mechanic working outside in the rain in a poorly lit area). After approximately 4 1/2 hours we were asked to runup the aircraft to make sure that the quantity and pressure remained normal for the #2 system. We also checked the # 1 system as well although we had not experienced any problems with the #1 system. The first officer and I were satisfied with the work done as was the mechanic. He signed off the write-up with the #2 system. We left the gate at XA10 am for white plains, ny. Approximately 35 mi south of philadelphia, PA (phl) while climbing thru fl 190 I (PF-captain) noticed that the #1 hydraulic quantity had dropped below 1.5 qts (minimum dispatch limit) and continued to drop at a good rate (not as fast as the rate drop of the #2 system at bwi). The first officer (PNF) requested a descent to 11000 ft and I called for the loss of hydraulic contents/pressure checklist page 18B. We entered a holding pattern at phl to complete all items of the checklist, discuss the ILS approach runway 9R (WX at the time was 200 ft visibility 1/2 mi), notified ATC we were declaring an emergency and diverting to pnl, notified the flight attendant that we would be on the ground in approximately 10 min and to prepare the cabin, notified our company dispatch of the problem and intentions. Prior to starting the approach we thoroughly discussed what components would be lost with the #1 hydraulic system inoperative - flaps, anti-skid, #1 inboard spoilers, normal brakes and ptu. We briefed for a zero flaps approach and landing. After touchdown we cleared the runway and stopped. After some discussion (#2 hydraulic psi normal quantity normal) we decided to taxi to the gate area. We arrived at the gate area and shut the aircraft down. The landing gear was pinned and the aircraft shocked. No injuries, no damage to the aircraft. Reflecting back on this incident, I would say the first officer and I made good use of cockpit resource management. There was no doubt at any time as to who was flying the aircraft and who was reading the checklist and doing the problem solving. The upper most thing in my mind was to maintain aircraft control and not let other problems distract me from that. The only thing I would have done different would be to have the aircraft towed to the gate area since we were using the emergency brake system.

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Original NASA ASRS Text

Title: FLT OF AN MDT DECLARED AN EMER AND DIVERTED TO LAND AT A NEAR BY ARPT DUE TO MAIN HYD SYS MALFUNCTION.

Narrative: AT APPROX AFTER COMPLETING ALL CHKLISTS INCLUDING THE AFTER START CHKLISTS WE CONTACTED GND FOR TAXI. (FLT #X TO WHITE PLAINS, NY (HPN)). IT WAS THEN THAT I (PF - CAPT) NOTICED THAT THE NO #2 HYD QUANTITY HAD DROPPED BELOW DISPATCH MINIMUMS (3.0 QTS) AND WAS CONTINUING TO DECREASE AT A RAPID RATE. WE IMMEDIATELY TAXIED BACK TO GATE. MAINT IN BALTIMORE, MD (BWI) WORKED ON THE ACFT (ACTUALLY IT WAS ONE MECH WORKING OUTSIDE IN THE RAIN IN A POORLY LIT AREA). AFTER APPROX 4 1/2 HRS WE WERE ASKED TO RUNUP THE ACFT TO MAKE SURE THAT THE QUANTITY AND PRESSURE REMAINED NORMAL FOR THE #2 SYS. WE ALSO CHKED THE # 1 SYS AS WELL ALTHOUGH WE HAD NOT EXPERIENCED ANY PROBS WITH THE #1 SYS. THE FO AND I WERE SATISFIED WITH THE WORK DONE AS WAS THE MECH. HE SIGNED OFF THE WRITE-UP WITH THE #2 SYS. WE LEFT THE GATE AT XA10 AM FOR WHITE PLAINS, NY. APPROX 35 MI S OF PHILADELPHIA, PA (PHL) WHILE CLBING THRU FL 190 I (PF-CAPT) NOTICED THAT THE #1 HYD QUANTITY HAD DROPPED BELOW 1.5 QTS (MINIMUM DISPATCH LIMIT) AND CONTINUED TO DROP AT A GOOD RATE (NOT AS FAST AS THE RATE DROP OF THE #2 SYS AT BWI). THE FO (PNF) REQUESTED A DSCNT TO 11000 FT AND I CALLED FOR THE LOSS OF HYD CONTENTS/PRESSURE CHKLIST PAGE 18B. WE ENTERED A HOLDING PATTERN AT PHL TO COMPLETE ALL ITEMS OF THE CHKLIST, DISCUSS THE ILS APCH RWY 9R (WX AT THE TIME WAS 200 FT VISIBILITY 1/2 MI), NOTIFIED ATC WE WERE DECLARING AN EMER AND DIVERTING TO PNL, NOTIFIED THE FLT ATTENDANT THAT WE WOULD BE ON THE GND IN APPROX 10 MIN AND TO PREPARE THE CABIN, NOTIFIED OUR COMPANY DISPATCH OF THE PROB AND INTENTIONS. PRIOR TO STARTING THE APCH WE THOROUGHLY DISCUSSED WHAT COMPONENTS WOULD BE LOST WITH THE #1 HYD SYS INOP - FLAPS, ANTI-SKID, #1 INBOARD SPOILERS, NORMAL BRAKES AND PTU. WE BRIEFED FOR A ZERO FLAPS APCH AND LNDG. AFTER TOUCHDOWN WE CLRED THE RWY AND STOPPED. AFTER SOME DISCUSSION (#2 HYD PSI NORMAL QUANTITY NORMAL) WE DECIDED TO TAXI TO THE GATE AREA. WE ARRIVED AT THE GATE AREA AND SHUT THE ACFT DOWN. THE LNDG GEAR WAS PINNED AND THE ACFT SHOCKED. NO INJURIES, NO DAMAGE TO THE ACFT. REFLECTING BACK ON THIS INCIDENT, I WOULD SAY THE FO AND I MADE GOOD USE OF COCKPIT RESOURCE MGMNT. THERE WAS NO DOUBT AT ANY TIME AS TO WHO WAS FLYING THE ACFT AND WHO WAS READING THE CHKLIST AND DOING THE PROBLEM SOLVING. THE UPPER MOST THING IN MY MIND WAS TO MAINTAIN ACFT CTL AND NOT LET OTHER PROBS DISTRACT ME FROM THAT. THE ONLY THING I WOULD HAVE DONE DIFFERENT WOULD BE TO HAVE THE ACFT TOWED TO THE GATE AREA SINCE WE WERE USING THE EMER BRAKE SYS.

Data retrieved from NASA's ASRS site as of July 2007 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.