Narrative:

While in cruise the hydr lookdown light illuminated. As pilot monitoring; I completed the memory items of hydr pump: off. At this point I delegated flying duties and radio communications to the first officer. Then I began the emergency action card and the hydraulics procedure. Since only the main accumulator was at the red line; the checklist led us to select the pump to ovrd; which I did. At this point the main accumulator recharged to normal and all the other indications still were in the green. The checklist led to hydraulic procedure #3 (loss of automatic mode) which informed us to switch between ovrd and off to maintain the pressure as well as switching to ovrd before configuration. Enroute I turned it to ovrd several times to recharge the main accumulator; one of these times the pump did seem to sound a little different than it normally does. Before configuration the pump was selected to ovrd again the accumulator was recharged and allowed the gear to fully extend as well as the flaps to extend to the full 20 degrees. As we were fully configured I concentrated on the approach again; but on short final (approx 500-1000 feet.) I looked down and noticed the accumulator was not being held at 3000 psi. At this point I briefed the first officer that full braking and steering capability may not be available on the rollout and runway exit. The landing occurred normally and on rollout I used very little braking and used some reverse to slow down. When some braking was used for the turn off with a little nose-wheel steering; the first officer observed the main accumulator was almost to the red line again. As we exited the runway; the hydr lookdown illuminated again and at this point I decided to straighten out the aircraft while I still had a little steering and braking left. We informed tower that we'd have to stop at our current position and would most likely have to be pulled by a tug in. I held the aircraft in place with use of the power levers; which worked just fine. The first officer then called operations asking if they could send a tug out to our location. I then added to ops that the crew coming out should have a headset and that we couldn't put the engines into feather until we were chocked so the aircraft wouldn't start rolling on its own. After speaking with the flight attendant and informing her of the situation and making sure everybody remained seated with their belts fastened we re-ran the checklist. Although the checklist now mostly referred to in flight situations; it led us to manually hand pumping the brakes which worked fine and allowed us to set the parking brake. We then waited for the ground crew to show up. When they did I spoke with a mechanic over the intercom who informed me the chocks were in place. I ensured the after landing check was complete and it was; I then shut down the engines and we completed the shutdown check; leaving the beacon on low and the batteries on. The mechanic installed all pins (nose and mains) and then they straightened the nosewheel which we were informed had castered. The front tires were in fine condition; so we began the towing operation. The tow and termination occurred without any incident. The hydraulic pump failed. We are trained for these exact situations in ground school as well as the simulator as the hydraulic system is pretty critical. The training was more than adequate for the situation and I am thankful I had it. Maintenance and ground operations handled it very well and it was apparent that they knew what they were doing. The only thing that lacked coverage was the hydraulic procedure; which seemed to mostly apply to situations in the air (taws flap to override; emergency gear extension; etc.); but it still worked in our situation. Also; add language in the hydraulic procedure cautioning crews from shutting down before the wheels are chocked.

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Original NASA ASRS Text

Title: In cruise a SF340 Captain experienced a hydraulic anomaly; which was interpreted as a failure of the auto mode. On short final with the pump in OVRD hydraulic pressure began to decrease and was eventually lost after crew cleared runway.

Narrative: While in cruise the HYDR lookdown light illuminated. As pilot monitoring; I completed the memory items of HYDR PUMP: OFF. At this point I delegated flying duties and radio communications to the First Officer. Then I began the emergency action card and the hydraulics procedure. Since only the main accumulator was at the red line; the checklist led us to select the pump to OVRD; which I did. At this point the main accumulator recharged to normal and all the other indications still were in the green. The checklist led to hydraulic procedure #3 (loss of AUTO mode) which informed us to switch between OVRD and OFF to maintain the pressure as well as switching to OVRD before configuration. Enroute I turned it to OVRD several times to recharge the main accumulator; one of these times the pump did seem to sound a little different than it normally does. Before configuration the pump was selected to OVRD again the accumulator was recharged and allowed the gear to fully extend as well as the flaps to extend to the full 20 degrees. As we were fully configured I concentrated on the approach again; but on short final (approx 500-1000 feet.) I looked down and noticed the accumulator was not being held at 3000 PSI. At this point I briefed the First Officer that full braking and steering capability may not be available on the rollout and runway exit. The landing occurred normally and on rollout I used very little braking and used some reverse to slow down. When some braking was used for the turn off with a little nose-wheel steering; the First Officer observed the main accumulator was almost to the red line again. As we exited the runway; the HYDR lookdown illuminated again and at this point I decided to straighten out the aircraft while I still had a little steering and braking left. We informed tower that we'd have to stop at our current position and would most likely have to be pulled by a tug in. I held the aircraft in place with use of the power levers; which worked just fine. The First Officer then called operations asking if they could send a tug out to our location. I then added to ops that the crew coming out should have a headset and that we couldn't put the engines into feather until we were chocked so the aircraft wouldn't start rolling on its own. After speaking with the Flight Attendant and informing her of the situation and making sure everybody remained seated with their belts fastened we re-ran the checklist. Although the checklist now mostly referred to in flight situations; it led us to manually hand pumping the brakes which worked fine and allowed us to set the parking brake. We then waited for the ground crew to show up. When they did I spoke with a mechanic over the intercom who informed me the chocks were in place. I ensured the after landing check was complete and it was; I then shut down the engines and we completed the shutdown check; leaving the beacon on low and the batteries on. The mechanic installed all pins (nose and mains) and then they straightened the nosewheel which we were informed had castered. The front tires were in fine condition; so we began the towing operation. The tow and termination occurred without any incident. The hydraulic pump failed. We are trained for these exact situations in ground school as well as the simulator as the hydraulic system is pretty critical. The training was more than adequate for the situation and I am thankful I had it. Maintenance and Ground Operations handled it very well and it was apparent that they knew what they were doing. The only thing that lacked coverage was the hydraulic procedure; which seemed to mostly apply to situations in the air (TAWS FLAP to OVERRIDE; emergency gear extension; etc.); but it still worked in our situation. Also; add language in the hydraulic procedure cautioning crews from shutting down before the wheels are chocked.

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.