Narrative:

Switched on auxiliary fuel tank on my small aircraft. Approximately 1 hour later with 2 hour estimated fuel on board engine started running erratically. Short burst of power/no power/ short burst of power. Felt like fuel was not flowing from tank to engine. Rather than attempting to reach airfield decided to land on large farm field. On final engine running worse so I turned it off, glided to a landing with no property damage to plane or farm and no personal harm to me or my wife (the only passenger). Problem appears to have been missing gasket on auxiliary tank and none in main tank. Plane took off with 25 gal uses 4 gpm. Total flight was 4 hour therefore, there should have been 9 gals remaining. The missing fuel gave us the clue. We were able to smell fuel all along fuselage from auxiliary tank towards the rear. The question remained of why the fuel remaining in auxiliary tank had not kept engine running. Speculated cause. The lost gasket allowed suction to suck out most of fuel from auxiliary tank. (Auxiliary tank fuel gauge is totally unreliable, time in flight only fuel measuring tool). The fuel remaining in auxiliary tank could not flow smoothly to engine because the vacuum created by lost cap was sufficient to keep remaining fuel from flowing by gravity. Solution. Auxiliary fuel tank is temporarily out of commission. Upon fueling the primary tank next day I was able to takeoff from farm lane after I inspected airplane. Reports of incident have been filed with nj department of transportation and state police. Prior to takeoff verified no damage.

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Original NASA ASRS Text

Title: FUEL PROBLEM, SPUTTERING ENGINE. PLT MAKES PRECAUTIONARY LNDG.

Narrative: SWITCHED ON AUX FUEL TANK ON MY SMA. APPROX 1 HR LATER WITH 2 HR ESTIMATED FUEL ON BOARD ENG STARTED RUNNING ERRATICALLY. SHORT BURST OF PWR/NO PWR/ SHORT BURST OF PWR. FELT LIKE FUEL WAS NOT FLOWING FROM TANK TO ENG. RATHER THAN ATTEMPTING TO REACH AIRFIELD DECIDED TO LAND ON LARGE FARM FIELD. ON FINAL ENG RUNNING WORSE SO I TURNED IT OFF, GLIDED TO A LNDG WITH NO PROPERTY DAMAGE TO PLANE OR FARM AND NO PERSONAL HARM TO ME OR MY WIFE (THE ONLY PAX). PROB APPEARS TO HAVE BEEN MISSING GASKET ON AUX TANK AND NONE IN MAIN TANK. PLANE TOOK OFF WITH 25 GAL USES 4 GPM. TOTAL FLT WAS 4 HR THEREFORE, THERE SHOULD HAVE BEEN 9 GALS REMAINING. THE MISSING FUEL GAVE US THE CLUE. WE WERE ABLE TO SMELL FUEL ALL ALONG FUSELAGE FROM AUX TANK TOWARDS THE REAR. THE QUESTION REMAINED OF WHY THE FUEL REMAINING IN AUX TANK HAD NOT KEPT ENG RUNNING. SPECULATED CAUSE. THE LOST GASKET ALLOWED SUCTION TO SUCK OUT MOST OF FUEL FROM AUX TANK. (AUX TANK FUEL GAUGE IS TOTALLY UNRELIABLE, TIME IN FLT ONLY FUEL MEASURING TOOL). THE FUEL REMAINING IN AUX TANK COULD NOT FLOW SMOOTHLY TO ENG BECAUSE THE VACUUM CREATED BY LOST CAP WAS SUFFICIENT TO KEEP REMAINING FUEL FROM FLOWING BY GRAVITY. SOLUTION. AUX FUEL TANK IS TEMPORARILY OUT OF COMMISSION. UPON FUELING THE PRIMARY TANK NEXT DAY I WAS ABLE TO TKOF FROM FARM LANE AFTER I INSPECTED AIRPLANE. RPTS OF INCIDENT HAVE BEEN FILED WITH NJ DEPT OF TRANSPORTATION AND STATE POLICE. PRIOR TO TKOF VERIFIED NO DAMAGE.

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.