Narrative:

I was flying VFR from bil to lws. About 30 NM east of mso, I discovered that I was unable to proceed VFR due to rising terrain meeting the low hanging clouds. I contacted mso FSS and received a clearance to proceed IFR via drummond VOR, mso VOR, direct to lws. While proceeding on this now INS flight, I was running on the auxiliary tanks. When they were close to empty, I tried to switch back to the mains. At this point, I was about 30 NM west of mso. The right fuel selector operated properly. However, the left selector was unable to select the main tank. It would select 'auxiliary' or 'off,' but when the selector lever was pushed all the way forward to 'main,' I could tell that the cable from the lever to the fuel valves was giving, rather than forcing the valves to the 'main' position. Other indications of this malfunction were that the left fuel gauge continued to indicate near empty, and the left fuel pressure gauge moved steadily toward 0. At this point, I knew that the left engine would fail momentarily due to fuel starvation. In my distress, and as a low-time multi engine pilot, it never occurred to me to use the xfeed, which would have fed both engines from the right main tank. Each main tank had about 2 hours of fuel, so I could have had 1 hour of fuel going to both engines if I had remembered the xfeed. I continued to run on right main and left auxiliary. I declared emergency to ZLC and reversed course to land at mso. Mso was below minimums for any approach, but fortunately, with the help of an extremely skilled approach/local controller at mso, I was directed to an almost VFR hole at the east end of the field and proceeded to land uneventfully. Uneventfully until the after landing roll, that is, when the left engine finally stopped completely due to fuel starvation. Not a moment too soon!! It's hard to say how one might prevent this from occurring in the future, other than to consider all the options when confronted with any given situation. Had I remembered the xfeed, the eventual result would have been the same, that is, landing at mso, but with a much greater margin of safety and far less stress. One thing I am very pleased with, on the other hand, is that I promptly declared an emergency. Many pilots have been bitten by waiting too long. I declared the minute I knew I had, or was going to have, a problem--and of that, I am proud. One comment to pilots who like to run 1 fuel tank dry before switching tanks: 'don't.' a fuel selector failure can ruin your whole day. Always switch tanks before you run down the operating tank below the level that will safely get you to an airport.

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Original NASA ASRS Text

Title: PLT OF SMA TWIN UNABLE TO SWITCH LEFT ENGINE TANK FROM AUX TANK TO LEFT MAIN DUE TO MALFUNCTIONING VALVE. DECLARED AN EMERGENCY AND LANDED MSO. UPON ROLLOUT THE LEFT ENGINE STOPPED BECAUSE OF FUEL STARVATION.

Narrative: I WAS FLYING VFR FROM BIL TO LWS. ABOUT 30 NM E OF MSO, I DISCOVERED THAT I WAS UNABLE TO PROCEED VFR DUE TO RISING TERRAIN MEETING THE LOW HANGING CLOUDS. I CONTACTED MSO FSS AND RECEIVED A CLRNC TO PROCEED IFR VIA DRUMMOND VOR, MSO VOR, DIRECT TO LWS. WHILE PROCEEDING ON THIS NOW INS FLT, I WAS RUNNING ON THE AUX TANKS. WHEN THEY WERE CLOSE TO EMPTY, I TRIED TO SWITCH BACK TO THE MAINS. AT THIS POINT, I WAS ABOUT 30 NM W OF MSO. THE RIGHT FUEL SELECTOR OPERATED PROPERLY. HOWEVER, THE LEFT SELECTOR WAS UNABLE TO SELECT THE MAIN TANK. IT WOULD SELECT 'AUX' OR 'OFF,' BUT WHEN THE SELECTOR LEVER WAS PUSHED ALL THE WAY FORWARD TO 'MAIN,' I COULD TELL THAT THE CABLE FROM THE LEVER TO THE FUEL VALVES WAS GIVING, RATHER THAN FORCING THE VALVES TO THE 'MAIN' POS. OTHER INDICATIONS OF THIS MALFUNCTION WERE THAT THE LEFT FUEL GAUGE CONTINUED TO INDICATE NEAR EMPTY, AND THE LEFT FUEL PRESSURE GAUGE MOVED STEADILY TOWARD 0. AT THIS POINT, I KNEW THAT THE LEFT ENG WOULD FAIL MOMENTARILY DUE TO FUEL STARVATION. IN MY DISTRESS, AND AS A LOW-TIME MULTI ENG PLT, IT NEVER OCCURRED TO ME TO USE THE XFEED, WHICH WOULD HAVE FED BOTH ENGS FROM THE RIGHT MAIN TANK. EACH MAIN TANK HAD ABOUT 2 HRS OF FUEL, SO I COULD HAVE HAD 1 HR OF FUEL GOING TO BOTH ENGS IF I HAD REMEMBERED THE XFEED. I CONTINUED TO RUN ON RIGHT MAIN AND LEFT AUX. I DECLARED EMER TO ZLC AND REVERSED COURSE TO LAND AT MSO. MSO WAS BELOW MINIMUMS FOR ANY APCH, BUT FORTUNATELY, WITH THE HELP OF AN EXTREMELY SKILLED APCH/LCL CTLR AT MSO, I WAS DIRECTED TO AN ALMOST VFR HOLE AT THE E END OF THE FIELD AND PROCEEDED TO LAND UNEVENTFULLY. UNEVENTFULLY UNTIL THE AFTER LNDG ROLL, THAT IS, WHEN THE LEFT ENG FINALLY STOPPED COMPLETELY DUE TO FUEL STARVATION. NOT A MOMENT TOO SOON!! IT'S HARD TO SAY HOW ONE MIGHT PREVENT THIS FROM OCCURRING IN THE FUTURE, OTHER THAN TO CONSIDER ALL THE OPTIONS WHEN CONFRONTED WITH ANY GIVEN SITUATION. HAD I REMEMBERED THE XFEED, THE EVENTUAL RESULT WOULD HAVE BEEN THE SAME, THAT IS, LNDG AT MSO, BUT WITH A MUCH GREATER MARGIN OF SAFETY AND FAR LESS STRESS. ONE THING I AM VERY PLEASED WITH, ON THE OTHER HAND, IS THAT I PROMPTLY DECLARED AN EMER. MANY PLTS HAVE BEEN BITTEN BY WAITING TOO LONG. I DECLARED THE MINUTE I KNEW I HAD, OR WAS GOING TO HAVE, A PROB--AND OF THAT, I AM PROUD. ONE COMMENT TO PLTS WHO LIKE TO RUN 1 FUEL TANK DRY BEFORE SWITCHING TANKS: 'DON'T.' A FUEL SELECTOR FAILURE CAN RUIN YOUR WHOLE DAY. ALWAYS SWITCH TANKS BEFORE YOU RUN DOWN THE OPERATING TANK BELOW THE LEVEL THAT WILL SAFELY GET YOU TO AN ARPT.

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.