Narrative:

While flying back from ZZZ1; approximately 15 mi from my home airport ZZZ2; the engine in my aircraft began to run rough. After checking fuel selector and engaging the electric fuel pump; the engine quit running. I had approximately 30 gallons of fuel in the aircraft when departing the home airport. The total flight down and back from ZZZ1 is approximately 24 mins. I picked out a field to land in; and accomplished a good landing without any damage or injuries to myself or the aircraft. The field was a hay field which was cut to approximately 6 inches; which slowed the aircraft down quickly. There was no damage such as ruts or grooves to the field. The owner was more than helpful and understanding. After checking the tanks after landing; there was not enough fuel in them to complete the flight. At the time of this letter; we were unable to determine the cause of the missing fuel. It is currently under FAA investigation. Callback conversation with reporter revealed the following information: reporter stated that after an inspection of the aircraft; it was determined that the most probable cause was a vapor lock. To remedy the situation; he installed a heat shield between the exhaust manifold and the fuel line. Following the modification; he departed the farm field and test flew the aircraft back to his home base. He reported that the engine did not actually quit but simply lost power and would not respond to throttle movements.

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Original NASA ASRS Text

Title: AN IAR 823 EXPERIENCED A PWR LOSS DUE TO A VAPOR LOCK AND COMPLETED A SAFE OFF FIELD LNDG.

Narrative: WHILE FLYING BACK FROM ZZZ1; APPROX 15 MI FROM MY HOME ARPT ZZZ2; THE ENG IN MY ACFT BEGAN TO RUN ROUGH. AFTER CHKING FUEL SELECTOR AND ENGAGING THE ELECTRIC FUEL PUMP; THE ENG QUIT RUNNING. I HAD APPROX 30 GALLONS OF FUEL IN THE ACFT WHEN DEPARTING THE HOME ARPT. THE TOTAL FLT DOWN AND BACK FROM ZZZ1 IS APPROX 24 MINS. I PICKED OUT A FIELD TO LAND IN; AND ACCOMPLISHED A GOOD LNDG WITHOUT ANY DAMAGE OR INJURIES TO MYSELF OR THE ACFT. THE FIELD WAS A HAY FIELD WHICH WAS CUT TO APPROX 6 INCHES; WHICH SLOWED THE ACFT DOWN QUICKLY. THERE WAS NO DAMAGE SUCH AS RUTS OR GROOVES TO THE FIELD. THE OWNER WAS MORE THAN HELPFUL AND UNDERSTANDING. AFTER CHKING THE TANKS AFTER LNDG; THERE WAS NOT ENOUGH FUEL IN THEM TO COMPLETE THE FLT. AT THE TIME OF THIS LETTER; WE WERE UNABLE TO DETERMINE THE CAUSE OF THE MISSING FUEL. IT IS CURRENTLY UNDER FAA INVESTIGATION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT AFTER AN INSPECTION OF THE ACFT; IT WAS DETERMINED THAT THE MOST PROBABLE CAUSE WAS A VAPOR LOCK. TO REMEDY THE SITUATION; HE INSTALLED A HEAT SHIELD BTWN THE EXHAUST MANIFOLD AND THE FUEL LINE. FOLLOWING THE MODIFICATION; HE DEPARTED THE FARM FIELD AND TEST FLEW THE ACFT BACK TO HIS HOME BASE. HE RPTED THAT THE ENG DID NOT ACTUALLY QUIT BUT SIMPLY LOST PWR AND WOULD NOT RESPOND TO THROTTLE MOVEMENTS.

Data retrieved from NASA's ASRS site as of January 2009 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.