Narrative:

Fuel exhaustion occurred due to a calculation of 8.2 gallons per hour based on a leaned mixture and high altitude when in fact the small aircraft figured out to use 8.8 gallons per hour. Total flight duration was 4.5 hours. I left marshall, mn, at XA30, flew to watertown, sd, (35 min), landed to pick up friends, took off at XB25. WX was clear, cool, and relatively calm. At rapid city, sd, I checked fuel tank levels -- right hand tank indicated 20 gallons, left tank 10 gallons. Based on that information, I continued on to destination without refueling since the distance to casper, wy, from rapid city was only approximately 165 statute mi, meaning I had 30 gallons of fuel indicated to travel that distance. I had an en route climb shortly after that from 6000 to 10500. This may have used a little extra fuel, however, I don't believe it to be that significant. 25 mi out, I contacted casper approach. Shortly after my right hand fuel tank was empty and showing a 4 gallon quantity. I switched tanks, turned on a fuel pump and informed approach of a fuel problem. They changed my approach to a straight-in. Then, to my surprise, my left tank was empty, indicating approximately a 2 gallon quantity. At that point my engine quit and I found a gravel road to land on. I had done a complete preflight on the plane. The tanks were full to the top of filler neck. I had checked the WX the night before at 2200 and again in the morning at 0400. The winds were forecast at 320 degree at 25 KTS.

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Original NASA ASRS Text

Title: AN SMA PLT RAN OUT OF FUEL WITH 6 GALLONS SHOWING IN HIS TANKS HE LANDED OFF FIELD CLOSE TO HIS DEST WITH NO RPTED DAMAGE OR INJURY.

Narrative: FUEL EXHAUSTION OCCURRED DUE TO A CALCULATION OF 8.2 GALLONS PER HR BASED ON A LEANED MIXTURE AND HIGH ALT WHEN IN FACT THE SMA FIGURED OUT TO USE 8.8 GALLONS PER HR. TOTAL FLT DURATION WAS 4.5 HRS. I LEFT MARSHALL, MN, AT XA30, FLEW TO WATERTOWN, SD, (35 MIN), LANDED TO PICK UP FRIENDS, TOOK OFF AT XB25. WX WAS CLR, COOL, AND RELATIVELY CALM. AT RAPID CITY, SD, I CHKED FUEL TANK LEVELS -- R HAND TANK INDICATED 20 GALLONS, L TANK 10 GALLONS. BASED ON THAT INFO, I CONTINUED ON TO DEST WITHOUT REFUELING SINCE THE DISTANCE TO CASPER, WY, FROM RAPID CITY WAS ONLY APPROX 165 STATUTE MI, MEANING I HAD 30 GALLONS OF FUEL INDICATED TO TRAVEL THAT DISTANCE. I HAD AN ENRTE CLB SHORTLY AFTER THAT FROM 6000 TO 10500. THIS MAY HAVE USED A LITTLE EXTRA FUEL, HOWEVER, I DON'T BELIEVE IT TO BE THAT SIGNIFICANT. 25 MI OUT, I CONTACTED CASPER APCH. SHORTLY AFTER MY R HAND FUEL TANK WAS EMPTY AND SHOWING A 4 GALLON QUANTITY. I SWITCHED TANKS, TURNED ON A FUEL PUMP AND INFORMED APCH OF A FUEL PROBLEM. THEY CHANGED MY APCH TO A STRAIGHT-IN. THEN, TO MY SURPRISE, MY L TANK WAS EMPTY, INDICATING APPROX A 2 GALLON QUANTITY. AT THAT POINT MY ENG QUIT AND I FOUND A GRAVEL ROAD TO LAND ON. I HAD DONE A COMPLETE PREFLT ON THE PLANE. THE TANKS WERE FULL TO THE TOP OF FILLER NECK. I HAD CHKED THE WX THE NIGHT BEFORE AT 2200 AND AGAIN IN THE MORNING AT 0400. THE WINDS WERE FORECAST AT 320 DEG AT 25 KTS.

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.