Narrative:

Departed the gate area with the right engine in feather and right high pressure bleed in automatic for maximum cabin cooling. Used differential thrust and nosewheel steering to make the sharp turn out of the gate area. At that time, I temporarily selected the hydraulic pump to override to ensure adequate hydraulic pressure in the accumualtors for making the sharp r-hand turn. Everything appeared to be working normally at this point. Ground control instructed us to follow a regional jet to runway 23 via taxiway a. During the taxi, the first officer completed the before takeoff check up to the condition levers and I then proceeded to turn off the high pressure bleed on the right engine and move the right condition lever into the minimum/maximum range. At this point, we were approaching the approach end of runway 23 behind the regional jet and the GA aircraft. While slowing the aircraft, we received a master caution 'hydraulics' on the central warning panel. Per procedure, I instructed the first officer to 'identify and cancel' which he completed. I selected the hydraulic pump to off. We observed the main accumulator approaching the red line. Additionally, the hydraulic quantity was normal, the emergency accumulator was normal, and the inboard and outboard brake accumulators were decreasing. I called for the 'QRH hydraulics' from the first officer. After analyzing the situation, we had hydraulic fluid and pressure in the emergency accumulator. I placed the hydraulic pump switch to override in an attempt to repressurize the main accumulator. The first officer informed ATC we needed some time to resolve a mechanical issue and started running the QRH. ATC wanted us to 'taxi into position and hold' because of traffic behind us. I informed ATC that we had a hydraulic problem and would not be moving the aircraft and suggested the traffic behind us go around via back taxi on runway 23. At this time, I cycled the hydraulic pump switch again (offirst officerverride) and concluded the pump was not working due to the absence of pressure in the main accumulator and the fact we could not hear the pump turn on when selected to override. The first officer suggested checking the circuit breakers at which time I located the 'automatic' and 'override' breakers on my side and recycled them accordingly. Again, I attempted to recycle the switch from (offirst officerverride) and it was obvious the pump had failed. The first officer was working in the QRH during this time period. In looking at the main and the brake accumulators, to our surprise, they were approaching 0 psi very rapidly (if not already at 0 psi). Awareness: at this point, the aircraft was positioned on the downwind sloping alpha taxiway (about A1 intersection) with a severe drop off in terrain to our immediate front and right. I must emphasize the severity of this situation was quite apparent since there was no overrun to our front or to the right, and the very steep drop off I can only estimate to be anywhere from 200-300 ft of wooded terrain. I became immediately concerned that we would lose our ability to turn and stop the aircraft at any moment and did not want to aggravate the situation with 'thrust producing' propellers. That is, while at ground idle with the condition levers in minimum/maximum range we were producing thrust. I was very concerned that once brake pressure was lost completely, we would begin rolling on the downsloping taxiway with no ability to turn or stop. We were presently in a stopped condition and I believed that by feathering the engines we could maintain status quo until we could manually pump the break accumulators (per the QRH) and have the aircraft chocked. I knew that by feathering the left engine we would have the ability to use asymmetrical thrust with power on the right engine to get us over in the grass on our left side between the taxiway and the runway (the only safe option). Consequently, I began to bring the left condition lever into feather. Simultaneously, the braking we previously had was lost and the aircraft began to move to the right. While rolling, I made several attempts to turn the aircraft with the nosewheel steering as well as braking with no success. Because I could neither stop nor steer the aircraft, the aircraft was gaining momentum, and because the aircraft was approaching the right side of the taxiway, we did not complete the QRH. I elected to apply power to the right engine and arrested the trend to the right, and we were successfully able to then establish a trend to the left as we continued to roll. While approaching the left side of the taxiway, it was apparent the left propeller was going to strike the taxiway/runway sign. I moved the left condition lever to fuel off 2-3 seconds prior to impact and the propeller struck the sign while the engine was spooling down. As we left the taxiway, we elected to shut the right engine down as well. We rolled to a stop in the grass between taxiway a and the approach end of runway 23.

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Original NASA ASRS Text

Title: TXWY EXCURSION AFTER A NEAR DROP OFF INTO A CANYON WHEN AN SF340 PIC LOSES CTL OF HIS ACFT ON THE TXWY WHEN UNDER PWR ON #1 ENG ONLY AND LOSES HIS HYD SYS DUE TO A PUMP FAILURE AT CRW, WV.

Narrative: DEPARTED THE GATE AREA WITH THE R ENG IN FEATHER AND R HIGH PRESSURE BLEED IN AUTO FOR MAX CABIN COOLING. USED DIFFERENTIAL THRUST AND NOSEWHEEL STEERING TO MAKE THE SHARP TURN OUT OF THE GATE AREA. AT THAT TIME, I TEMPORARILY SELECTED THE HYD PUMP TO OVERRIDE TO ENSURE ADEQUATE HYD PRESSURE IN THE ACCUMUALTORS FOR MAKING THE SHARP R-HAND TURN. EVERYTHING APPEARED TO BE WORKING NORMALLY AT THIS POINT. GND CTL INSTRUCTED US TO FOLLOW A REGIONAL JET TO RWY 23 VIA TXWY A. DURING THE TAXI, THE FO COMPLETED THE BEFORE TKOF CHK UP TO THE CONDITION LEVERS AND I THEN PROCEEDED TO TURN OFF THE HIGH PRESSURE BLEED ON THE R ENG AND MOVE THE R CONDITION LEVER INTO THE MINIMUM/MAXIMUM RANGE. AT THIS POINT, WE WERE APCHING THE APCH END OF RWY 23 BEHIND THE REGIONAL JET AND THE GA ACFT. WHILE SLOWING THE ACFT, WE RECEIVED A MASTER CAUTION 'HYDS' ON THE CENTRAL WARNING PANEL. PER PROC, I INSTRUCTED THE FO TO 'IDENT AND CANCEL' WHICH HE COMPLETED. I SELECTED THE HYD PUMP TO OFF. WE OBSERVED THE MAIN ACCUMULATOR APCHING THE RED LINE. ADDITIONALLY, THE HYD QUANTITY WAS NORMAL, THE EMER ACCUMULATOR WAS NORMAL, AND THE INBOARD AND OUTBOARD BRAKE ACCUMULATORS WERE DECREASING. I CALLED FOR THE 'QRH HYDS' FROM THE FO. AFTER ANALYZING THE SIT, WE HAD HYD FLUID AND PRESSURE IN THE EMER ACCUMULATOR. I PLACED THE HYD PUMP SWITCH TO OVERRIDE IN AN ATTEMPT TO REPRESSURIZE THE MAIN ACCUMULATOR. THE FO INFORMED ATC WE NEEDED SOME TIME TO RESOLVE A MECHANICAL ISSUE AND STARTED RUNNING THE QRH. ATC WANTED US TO 'TAXI INTO POS AND HOLD' BECAUSE OF TFC BEHIND US. I INFORMED ATC THAT WE HAD A HYD PROB AND WOULD NOT BE MOVING THE ACFT AND SUGGESTED THE TFC BEHIND US GO AROUND VIA BACK TAXI ON RWY 23. AT THIS TIME, I CYCLED THE HYD PUMP SWITCH AGAIN (OFF/OVERRIDE) AND CONCLUDED THE PUMP WAS NOT WORKING DUE TO THE ABSENCE OF PRESSURE IN THE MAIN ACCUMULATOR AND THE FACT WE COULD NOT HEAR THE PUMP TURN ON WHEN SELECTED TO OVERRIDE. THE FO SUGGESTED CHKING THE CIRCUIT BREAKERS AT WHICH TIME I LOCATED THE 'AUTO' AND 'OVERRIDE' BREAKERS ON MY SIDE AND RECYCLED THEM ACCORDINGLY. AGAIN, I ATTEMPTED TO RECYCLE THE SWITCH FROM (OFF/OVERRIDE) AND IT WAS OBVIOUS THE PUMP HAD FAILED. THE FO WAS WORKING IN THE QRH DURING THIS TIME PERIOD. IN LOOKING AT THE MAIN AND THE BRAKE ACCUMULATORS, TO OUR SURPRISE, THEY WERE APCHING 0 PSI VERY RAPIDLY (IF NOT ALREADY AT 0 PSI). AWARENESS: AT THIS POINT, THE ACFT WAS POSITIONED ON THE DOWNWIND SLOPING ALPHA TXWY (ABOUT A1 INTXN) WITH A SEVERE DROP OFF IN TERRAIN TO OUR IMMEDIATE FRONT AND R. I MUST EMPHASIZE THE SEVERITY OF THIS SIT WAS QUITE APPARENT SINCE THERE WAS NO OVERRUN TO OUR FRONT OR TO THE R, AND THE VERY STEEP DROP OFF I CAN ONLY ESTIMATE TO BE ANYWHERE FROM 200-300 FT OF WOODED TERRAIN. I BECAME IMMEDIATELY CONCERNED THAT WE WOULD LOSE OUR ABILITY TO TURN AND STOP THE ACFT AT ANY MOMENT AND DID NOT WANT TO AGGRAVATE THE SIT WITH 'THRUST PRODUCING' PROPS. THAT IS, WHILE AT GND IDLE WITH THE CONDITION LEVERS IN MINIMUM/MAXIMUM RANGE WE WERE PRODUCING THRUST. I WAS VERY CONCERNED THAT ONCE BRAKE PRESSURE WAS LOST COMPLETELY, WE WOULD BEGIN ROLLING ON THE DOWNSLOPING TXWY WITH NO ABILITY TO TURN OR STOP. WE WERE PRESENTLY IN A STOPPED CONDITION AND I BELIEVED THAT BY FEATHERING THE ENGS WE COULD MAINTAIN STATUS QUO UNTIL WE COULD MANUALLY PUMP THE BREAK ACCUMULATORS (PER THE QRH) AND HAVE THE ACFT CHOCKED. I KNEW THAT BY FEATHERING THE L ENG WE WOULD HAVE THE ABILITY TO USE ASYMMETRICAL THRUST WITH PWR ON THE R ENG TO GET US OVER IN THE GRASS ON OUR L SIDE BTWN THE TXWY AND THE RWY (THE ONLY SAFE OPTION). CONSEQUENTLY, I BEGAN TO BRING THE L CONDITION LEVER INTO FEATHER. SIMULTANEOUSLY, THE BRAKING WE PREVIOUSLY HAD WAS LOST AND THE ACFT BEGAN TO MOVE TO THE R. WHILE ROLLING, I MADE SEVERAL ATTEMPTS TO TURN THE ACFT WITH THE NOSEWHEEL STEERING AS WELL AS BRAKING WITH NO SUCCESS. BECAUSE I COULD NEITHER STOP NOR STEER THE ACFT, THE ACFT WAS GAINING MOMENTUM, AND BECAUSE THE ACFT WAS APCHING THE R SIDE OF THE TXWY, WE DID NOT COMPLETE THE QRH. I ELECTED TO APPLY PWR TO THE R ENG AND ARRESTED THE TREND TO THE R, AND WE WERE SUCCESSFULLY ABLE TO THEN ESTABLISH A TREND TO THE L AS WE CONTINUED TO ROLL. WHILE APCHING THE L SIDE OF THE TXWY, IT WAS APPARENT THE L PROP WAS GOING TO STRIKE THE TXWY/RWY SIGN. I MOVED THE L CONDITION LEVER TO FUEL OFF 2-3 SECONDS PRIOR TO IMPACT AND THE PROP STRUCK THE SIGN WHILE THE ENG WAS SPOOLING DOWN. AS WE LEFT THE TXWY, WE ELECTED TO SHUT THE R ENG DOWN AS WELL. WE ROLLED TO A STOP IN THE GRASS BTWN TXWY A AND THE APCH END OF RWY 23.

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.