Narrative:

While en route we were making a decent to 6;000 ft. We noticed the autopilot had kicked off and we had a master caution elec look up light illuminated. We saw the left ess bus and left main bus lights were illuminated as well as the avionics vent light and rudder limit light. The captain who was pilot flying handed control over to me as his entire instrument panel was inoperative. I slowed to 170 KIAS because of the rudder limit light. The captain proceeded to run the QRH for left ess bus and left main bus lights. When we discovered that we had lost hydraulic pump control in both auto and override modes. I called gear down. We observed a hydr look down light and only the nose landing gear indicator light was illuminated. We preformed a go around at approximately 1;700 ft MSL and asked ATC for holding while we worked on our landing gear issue. The captain preformed the hydr look down light QRH which instructed him to pull the emergency gear extension handle. We transferred controls so I could pull the emergency gear extend handle; and transferred them back once I had completed the task. We asked ATC for the longest runway for landing. The captain made the decision to stop on the runway and get towed to the gate as per the checklist in the QRH noting that he would not have nose wheel steering once we landed. Because we were in visual conditions I continued flying the aircraft until we were established on final approach so the captain had time to brief the flight attendant and passengers. Once on final the captain and I transferred controls and he preformed the landing; stopping and shutting down on the runway. After landing we made the decision to pin all 3 gear for towing in due to the uncertain condition of our hydraulics.

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Original NASA ASRS Text

Title: SF340 First Officer reports loss of the L MAIN and ESS BUSES during descent for landing. A go around is initiated when the landing gear cannot be lowered normally due to loss of hydraulic pump control. The emergency gear extension handle is used and a normal landing ensues.

Narrative: While en route we were making a decent to 6;000 FT. We noticed the autopilot had kicked off and we had a master caution ELEC look up light illuminated. We saw the L ESS BUS and L MAIN BUS lights were illuminated as well as the AVIONICS VENT Light and RUDDER LIMIT Light. The Captain who was pilot flying handed control over to me as his entire instrument panel was inoperative. I slowed to 170 KIAS because of the rudder limit light. The Captain proceeded to run the QRH for L ESS BUS and L MAIN BUS lights. When we discovered that we had lost hydraulic pump control in both auto and override modes. I called gear down. We observed a HYDR look down light and only the nose landing gear indicator light was illuminated. We preformed a go around at approximately 1;700 FT MSL and asked ATC for holding while we worked on our landing gear issue. The Captain preformed the HYDR look down light QRH which instructed him to pull the emergency gear extension handle. We transferred controls so I could pull the emergency gear extend handle; and transferred them back once I had completed the task. We asked ATC for the longest runway for landing. The Captain made the decision to stop on the runway and get towed to the gate as per the checklist in the QRH noting that he would not have nose wheel steering once we landed. Because we were in visual conditions I continued flying the aircraft until we were established on final approach so the Captain had time to brief the Flight Attendant and passengers. Once on final the Captain and I transferred controls and he preformed the landing; stopping and shutting down on the runway. After landing we made the decision to pin all 3 gear for towing in due to the uncertain condition of our hydraulics.

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.