Narrative:

Aug 1988, while returning from lake texoma lodge, I was at 3000' MSL, along with a friend who was in his small aircraft. We started our descent for approach to dallas north airport (straight in landing on runway 16). The descent started at about 5 mi from the airport. On reaching and passing through 1900' MSL, the engine began to bog down. My first reaction was to recheck the mixture control (which was in full rich), check carburetor heat, and increase the throttle about three-eighths inches. That was to no avail. Then throttle to full power. Also to no avail. At that point, I was about 3 mi from the runway and crossing highway 121. The engine made no attempt to run right and began to windmill and then, within a few second, quit. It was my decision to make a shallow left turn and make a dead stick landing on highway 121 past the red light intersection, where there was no power line poles or crossover wires. (That area is my home base and I traveled that road many times and have noted that there is no overhead lines for a few mi.) my other alternative was to try to get as close to the airport as I possibly could, and land in a known freshly plowed field that has shrub brush and semi-rough terrain. My estimated landing site at that point was only 1 to 1 and a quarter mi. Still nearly 3 mi from the airport, the decision to land on highway 121 was made and executed west/O flaw. There was light traffic on the roadway, and a textbook dead stick landing was made. On exiting the aircraft, I immediately positioned the aircraft to where it was not entirely in the roadway the best that I could. I was aided by an unknown motorist that had stopped to see what was happening. I then began hunting for a cause of the engine quitting like it did. I had plenty of gas, approximately 6 gals in each wing, between one-quarter and one-half tank indicated on the panel. A visual inspection of the tank revealed that I did indeed have more than enough gas to continue flying for 45 more min with 45 min reserve. I thought that there might be water in the fuel (preflight did not reveal any at takeoff). On checking the wing quick drains, no sign of water was found. On inspection of the gascolator, I found that it had not completely closed, though it was not leaking. I am aware of problems that have been reported that the vacuum caused by a quick descent could cause the gascolator to not feed the carburetor properly if not properly seated. On checking that point (the lowest point in the fuel system) for possible contaminants, none were found. I then decided to see if it would start, even though a restart was unsuccessful on the way down. The aircraft started on the second spin of the propeller as it normally does and ran fine. I did a full static run up with leaning procedures and magnetic checks at different rpms. The machine ran as advertised west/O flaw. I had good oil pressure and temperature. There seemed to be nothing wrong at this point. Extra fuel was added as a precaution as it was dark and lighting was poor and flashlights were a help, but no substitute for an extra margin of safety in an exciting moment. (The friend that I was flying back with landed at dallas north and brought out 10 extra gals, that giving me almost a full tank.) even though the machine was running as normal and the static run up revealed no problem. I can only speculate that the gascolator not properly seating was my problem. I was not allowed to take off by the highway patrol by direction of the local FAA office, and forced to taxi some 4 and one-half mi to the airport. On reaching the airport (which by the way was no fun trip, having to dodge sign post and mail boxes, trees, etc.), I took the aircraft around the pattern to check it out. There were no flaws in either takeoff or landing. Everything was working properly. On aug 1988, I took the aircraft to my mechanic for a look see, i.e., the gascolator and reset the trim tab.

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Original NASA ASRS Text

Title: SMA ENGINE FAILURE RESULTS IN OFF ARPT LNDG ON HIGHWAY. NO DAMAGE TO ACFT OR INJURIES.

Narrative: AUG 1988, WHILE RETURNING FROM LAKE TEXOMA LODGE, I WAS AT 3000' MSL, ALONG WITH A FRIEND WHO WAS IN HIS SMA. WE STARTED OUR DSCNT FOR APCH TO DALLAS NORTH AIRPORT (STRAIGHT IN LNDG ON RWY 16). THE DSCNT STARTED AT ABOUT 5 MI FROM THE ARPT. ON REACHING AND PASSING THROUGH 1900' MSL, THE ENGINE BEGAN TO BOG DOWN. MY FIRST REACTION WAS TO RECHECK THE MIXTURE CTL (WHICH WAS IN FULL RICH), CHECK CARB HEAT, AND INCREASE THE THROTTLE ABOUT THREE-EIGHTHS INCHES. THAT WAS TO NO AVAIL. THEN THROTTLE TO FULL POWER. ALSO TO NO AVAIL. AT THAT POINT, I WAS ABOUT 3 MI FROM THE RWY AND XING HWY 121. THE ENGINE MADE NO ATTEMPT TO RUN RIGHT AND BEGAN TO WINDMILL AND THEN, WITHIN A FEW SEC, QUIT. IT WAS MY DECISION TO MAKE A SHALLOW LEFT TURN AND MAKE A DEAD STICK LNDG ON HWY 121 PAST THE RED LIGHT INTXN, WHERE THERE WAS NO POWER LINE POLES OR CROSSOVER WIRES. (THAT AREA IS MY HOME BASE AND I TRAVELED THAT ROAD MANY TIMES AND HAVE NOTED THAT THERE IS NO OVERHEAD LINES FOR A FEW MI.) MY OTHER ALTERNATIVE WAS TO TRY TO GET AS CLOSE TO THE ARPT AS I POSSIBLY COULD, AND LAND IN A KNOWN FRESHLY PLOWED FIELD THAT HAS SHRUB BRUSH AND SEMI-ROUGH TERRAIN. MY ESTIMATED LNDG SITE AT THAT POINT WAS ONLY 1 TO 1 AND A QUARTER MI. STILL NEARLY 3 MI FROM THE ARPT, THE DECISION TO LAND ON HWY 121 WAS MADE AND EXECUTED W/O FLAW. THERE WAS LIGHT TFC ON THE ROADWAY, AND A TEXTBOOK DEAD STICK LNDG WAS MADE. ON EXITING THE ACFT, I IMMEDIATELY POSITIONED THE ACFT TO WHERE IT WAS NOT ENTIRELY IN THE ROADWAY THE BEST THAT I COULD. I WAS AIDED BY AN UNKNOWN MOTORIST THAT HAD STOPPED TO SEE WHAT WAS HAPPENING. I THEN BEGAN HUNTING FOR A CAUSE OF THE ENGINE QUITTING LIKE IT DID. I HAD PLENTY OF GAS, APPROX 6 GALS IN EACH WING, BTWN ONE-QUARTER AND ONE-HALF TANK INDICATED ON THE PANEL. A VISUAL INSPECTION OF THE TANK REVEALED THAT I DID INDEED HAVE MORE THAN ENOUGH GAS TO CONTINUE FLYING FOR 45 MORE MIN WITH 45 MIN RESERVE. I THOUGHT THAT THERE MIGHT BE WATER IN THE FUEL (PREFLT DID NOT REVEAL ANY AT TKOF). ON CHKING THE WING QUICK DRAINS, NO SIGN OF WATER WAS FOUND. ON INSPECTION OF THE GASCOLATOR, I FOUND THAT IT HAD NOT COMPLETELY CLOSED, THOUGH IT WAS NOT LEAKING. I AM AWARE OF PROBLEMS THAT HAVE BEEN RPTED THAT THE VACUUM CAUSED BY A QUICK DSCNT COULD CAUSE THE GASCOLATOR TO NOT FEED THE CARB PROPERLY IF NOT PROPERLY SEATED. ON CHKING THAT POINT (THE LOWEST POINT IN THE FUEL SYS) FOR POSSIBLE CONTAMINANTS, NONE WERE FOUND. I THEN DECIDED TO SEE IF IT WOULD START, EVEN THOUGH A RESTART WAS UNSUCCESSFUL ON THE WAY DOWN. THE ACFT STARTED ON THE SECOND SPIN OF THE PROP AS IT NORMALLY DOES AND RAN FINE. I DID A FULL STATIC RUN UP WITH LEANING PROCS AND MAG CHKS AT DIFFERENT RPMS. THE MACHINE RAN AS ADVERTISED W/O FLAW. I HAD GOOD OIL PRESSURE AND TEMP. THERE SEEMED TO BE NOTHING WRONG AT THIS POINT. EXTRA FUEL WAS ADDED AS A PRECAUTION AS IT WAS DARK AND LIGHTING WAS POOR AND FLASHLIGHTS WERE A HELP, BUT NO SUBSTITUTE FOR AN EXTRA MARGIN OF SAFETY IN AN EXCITING MOMENT. (THE FRIEND THAT I WAS FLYING BACK WITH LANDED AT DALLAS NORTH AND BROUGHT OUT 10 EXTRA GALS, THAT GIVING ME ALMOST A FULL TANK.) EVEN THOUGH THE MACHINE WAS RUNNING AS NORMAL AND THE STATIC RUN UP REVEALED NO PROB. I CAN ONLY SPECULATE THAT THE GASCOLATOR NOT PROPERLY SEATING WAS MY PROB. I WAS NOT ALLOWED TO TAKE OFF BY THE HWY PATROL BY DIRECTION OF THE LOCAL FAA OFFICE, AND FORCED TO TAXI SOME 4 AND ONE-HALF MI TO THE ARPT. ON REACHING THE ARPT (WHICH BY THE WAY WAS NO FUN TRIP, HAVING TO DODGE SIGN POST AND MAIL BOXES, TREES, ETC.), I TOOK THE ACFT AROUND THE PATTERN TO CHK IT OUT. THERE WERE NO FLAWS IN EITHER TKOF OR LNDG. EVERYTHING WAS WORKING PROPERLY. ON AUG 1988, I TOOK THE ACFT TO MY MECHANIC FOR A LOOK SEE, I.E., THE GASCOLATOR AND RESET THE TRIM TAB.

Data retrieved from NASA's ASRS site as of August 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.