Narrative:

Flight began after filling both wing tanks totaling 21 united states gallons. After 45 mins of normal cruise, engine quit without warning. Tried restarting after confirming that fuel selectors were 'on.' I was able to select 3 different emergency landing spots. I chose one which was smooth and grassy and whose approach was clear of personal property. The landing was made uneventfully. The aircraft received no damage. I folded the wings and had the aircraft out of the field within 55 mins. The aircraft can be towed behind a car once the wings are folded back. After returning the plane to my shop I checked the fuel level in both tanks. I still had 17 gallons on board. I noticed that the right tank was missing its fuel cap. I checked the entire fuel system and discovered that the fuel line between the tanks and the header tank was air bound. I disassembled the entire fuel system to confirm that it was completely clear and in perfect operating condition. I determined that flight without the gas cap caused a decreased pressure in the fuel tanks which are a gravity feed system. Without the normal head pressure to feed the vacuum driven fuel pump, air was introduced into the system as the vacuum pump strained to suck the fuel. I determined that this is possible in a 20 degree bank. The gas caps provide a positive pressure in flight. Without 1 or both caps in place, this problem can occur. Before returning to flight, I installed a visual fuel level tube to positively show me the level of fuel in the 1.5 gallon. Header tank. This has become a regularly scanned instrument now on all flts. This now will give me a 20 min notice of a fuel tank problem. I shall always double check fuel cap security. There was 1 passenger on board during this emergency landing. The landing was normal and smooth. Touchdown speed on my aircraft is 28 to 30 mph in a full stall landing. My rollout was about 75 ft after braking. Neither myself or my passenger received any injury. Callback conversation with reporter revealed the following information: reporter states the problem arose because he did a fairly steep bank which caused air to enter fuel system. Aircraft flies so slowly that fuel did not siphon out but allowed air in. Has solved any future problem with a facet boost fuel pump which develops constant fuel feed. Feels this was all caused by his not getting fuel cap on tightly. Has organized 100 kit builders and none have had any problem. Contacted the factory to doublechk as well.

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Original NASA ASRS Text

Title: HOMEBUILT SMA AT CRUSE WHEN ENG FAILS. EMER LNDG.

Narrative: FLT BEGAN AFTER FILLING BOTH WING TANKS TOTALING 21 UNITED STATES GALLONS. AFTER 45 MINS OF NORMAL CRUISE, ENG QUIT WITHOUT WARNING. TRIED RESTARTING AFTER CONFIRMING THAT FUEL SELECTORS WERE 'ON.' I WAS ABLE TO SELECT 3 DIFFERENT EMER LNDG SPOTS. I CHOSE ONE WHICH WAS SMOOTH AND GRASSY AND WHOSE APCH WAS CLR OF PERSONAL PROPERTY. THE LNDG WAS MADE UNEVENTFULLY. THE ACFT RECEIVED NO DAMAGE. I FOLDED THE WINGS AND HAD THE ACFT OUT OF THE FIELD WITHIN 55 MINS. THE ACFT CAN BE TOWED BEHIND A CAR ONCE THE WINGS ARE FOLDED BACK. AFTER RETURNING THE PLANE TO MY SHOP I CHKED THE FUEL LEVEL IN BOTH TANKS. I STILL HAD 17 GALLONS ON BOARD. I NOTICED THAT THE R TANK WAS MISSING ITS FUEL CAP. I CHKED THE ENTIRE FUEL SYS AND DISCOVERED THAT THE FUEL LINE BTWN THE TANKS AND THE HEADER TANK WAS AIR BOUND. I DISASSEMBLED THE ENTIRE FUEL SYS TO CONFIRM THAT IT WAS COMPLETELY CLR AND IN PERFECT OPERATING CONDITION. I DETERMINED THAT FLT WITHOUT THE GAS CAP CAUSED A DECREASED PRESSURE IN THE FUEL TANKS WHICH ARE A GRAVITY FEED SYS. WITHOUT THE NORMAL HEAD PRESSURE TO FEED THE VACUUM DRIVEN FUEL PUMP, AIR WAS INTRODUCED INTO THE SYS AS THE VACUUM PUMP STRAINED TO SUCK THE FUEL. I DETERMINED THAT THIS IS POSSIBLE IN A 20 DEG BANK. THE GAS CAPS PROVIDE A POSITIVE PRESSURE IN FLT. WITHOUT 1 OR BOTH CAPS IN PLACE, THIS PROBLEM CAN OCCUR. BEFORE RETURNING TO FLT, I INSTALLED A VISUAL FUEL LEVEL TUBE TO POSITIVELY SHOW ME THE LEVEL OF FUEL IN THE 1.5 GALLON. HEADER TANK. THIS HAS BECOME A REGULARLY SCANNED INST NOW ON ALL FLTS. THIS NOW WILL GIVE ME A 20 MIN NOTICE OF A FUEL TANK PROBLEM. I SHALL ALWAYS DOUBLE CHK FUEL CAP SECURITY. THERE WAS 1 PAX ON BOARD DURING THIS EMER LNDG. THE LNDG WAS NORMAL AND SMOOTH. TOUCHDOWN SPD ON MY ACFT IS 28 TO 30 MPH IN A FULL STALL LNDG. MY ROLLOUT WAS ABOUT 75 FT AFTER BRAKING. NEITHER MYSELF OR MY PAX RECEIVED ANY INJURY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THE PROBLEM AROSE BECAUSE HE DID A FAIRLY STEEP BANK WHICH CAUSED AIR TO ENTER FUEL SYS. ACFT FLIES SO SLOWLY THAT FUEL DID NOT SIPHON OUT BUT ALLOWED AIR IN. HAS SOLVED ANY FUTURE PROBLEM WITH A FACET BOOST FUEL PUMP WHICH DEVELOPS CONSTANT FUEL FEED. FEELS THIS WAS ALL CAUSED BY HIS NOT GETTING FUEL CAP ON TIGHTLY. HAS ORGANIZED 100 KIT BUILDERS AND NONE HAVE HAD ANY PROBLEM. CONTACTED THE FACTORY TO DOUBLECHK AS WELL.

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.