Narrative:

Captain flying. Flight was dispatched with left air-conditioning pack inoperative and flight limited to FL250. The aircraft was MD83 with 3 position center fuel tank pump switches. During the just priors, the captain inadvertently moved the center tank pump switches on position forward, from disabled to off. From my scan, the switches appeared to be in the on position. After departure, we were cleared via several vectors and ultimately ONS direct to tex early in the flight. After the SID, we never passed over any of the miscellaneous 14 chkpoints. At FL250, prior to tex, the right engine began to wind down. Because the left air- conditioning pack was inoperative and the cabin altitude began to climb, we immediately requested an emergency descent and started down to 14000 ft. We simultaneously observed that the center fuel tank pump switches were not on and immediately turned them on. The captain placed the ignition to override and the right engine operation returned to normal. Because we were in a descent with the power at idle and the left air-conditioning off, the cabin continued to climb and reached approximately 10500 ft. At that time we ejected the passenger oxygen masks. With normal engine and cabin altitude restored, we continued uneventfully to aus. The importance of keeping an up-to- date fuel log and scan along with checklist discipline cannot be overemphasized. Long, direct clrncs without passing miscellaneous 14 chkpoints and the 3 position center tank fuel pump switches were contributory factors. Supplemental information from acn 345078: this aircraft had auxiliary fuel tanks with 3 position fuel pumps. When just prior checklist was read, I moved each fuel pump switch 1 position forward. This inadvertently left the center pumps in the off position. In addition, I would recommend that those aircraft having the 3 position center fuel pumps be changed to 2 position switches.

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Original NASA ASRS Text

Title: MD83 DISPATCHED WITH L AIR-CONDITIONING PACK INOP. LIMITED TO FL250. ACFT HAD 3 POS CTR TANK PUMP SWITCH. CAPT INADVERTENTLY TURNED FUEL PUMP SWITCH TO OFF AND AT FL250 R ENG BEGAN TO SPOOL DOWN. STARTED DSCNT TO 14000 FT AS THE CABIN WAS LOSING PRESSURE. CABIN REACHED 10500 FT AND THE FLC ACTIVATED THE CABIN OXYGEN SYS. TURNED ON CTR TANK BOOST AND R ENG RESTARTED. CONTINUED FLT TO AUS AT 14000 FT.

Narrative: CAPT FLYING. FLT WAS DISPATCHED WITH L AIR-CONDITIONING PACK INOP AND FLT LIMITED TO FL250. THE ACFT WAS MD83 WITH 3 POS CTR FUEL TANK PUMP SWITCHES. DURING THE JUST PRIORS, THE CAPT INADVERTENTLY MOVED THE CTR TANK PUMP SWITCHES ON POS FORWARD, FROM DISABLED TO OFF. FROM MY SCAN, THE SWITCHES APPEARED TO BE IN THE ON POS. AFTER DEP, WE WERE CLRED VIA SEVERAL VECTORS AND ULTIMATELY ONS DIRECT TO TEX EARLY IN THE FLT. AFTER THE SID, WE NEVER PASSED OVER ANY OF THE MISC 14 CHKPOINTS. AT FL250, PRIOR TO TEX, THE R ENG BEGAN TO WIND DOWN. BECAUSE THE L AIR- CONDITIONING PACK WAS INOP AND THE CABIN ALT BEGAN TO CLB, WE IMMEDIATELY REQUESTED AN EMER DSCNT AND STARTED DOWN TO 14000 FT. WE SIMULTANEOUSLY OBSERVED THAT THE CTR FUEL TANK PUMP SWITCHES WERE NOT ON AND IMMEDIATELY TURNED THEM ON. THE CAPT PLACED THE IGNITION TO OVERRIDE AND THE R ENG OP RETURNED TO NORMAL. BECAUSE WE WERE IN A DSCNT WITH THE PWR AT IDLE AND THE L AIR-CONDITIONING OFF, THE CABIN CONTINUED TO CLB AND REACHED APPROX 10500 FT. AT THAT TIME WE EJECTED THE PAX OXYGEN MASKS. WITH NORMAL ENG AND CABIN ALT RESTORED, WE CONTINUED UNEVENTFULLY TO AUS. THE IMPORTANCE OF KEEPING AN UP-TO- DATE FUEL LOG AND SCAN ALONG WITH CHKLIST DISCIPLINE CANNOT BE OVEREMPHASIZED. LONG, DIRECT CLRNCS WITHOUT PASSING MISC 14 CHKPOINTS AND THE 3 POS CTR TANK FUEL PUMP SWITCHES WERE CONTRIBUTORY FACTORS. SUPPLEMENTAL INFO FROM ACN 345078: THIS ACFT HAD AUX FUEL TANKS WITH 3 POS FUEL PUMPS. WHEN JUST PRIOR CHKLIST WAS READ, I MOVED EACH FUEL PUMP SWITCH 1 POS FORWARD. THIS INADVERTENTLY LEFT THE CTR PUMPS IN THE OFF POS. IN ADDITION, I WOULD RECOMMEND THAT THOSE ACFT HAVING THE 3 POS CTR FUEL PUMPS BE CHANGED TO 2 POS SWITCHES.

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.