Narrative:

After purchasing the aircraft, an small aircraft, on 5/X/91, I proceeded to fly 46 +/- hours with engine roughness on 2 occasions. Each time upon landing it was assumed to have been water in the fuel or carburetor ice. Each occurrence had about 40 hours between them. Then after cruising approaching a 3 hour flight the engine quit (all previous flts had been 2-2 1/2 long). An off airport landing was made in a rough 800-1100 ft hay field. A mechanic the next day could not find the cause of engine failure. Aircraft was flown out and refueled for 1 1/2 hour flight home. All fuel screens were clear and clean. At home port the investigation went on. Then as a last resort fuel flow was checked from each tank not both. Left tank would not flow sufficient fuel to operate engine. Tank flowed freely but not past fuel selector valve. The valve was removed and the left port found plugged with silicone caulking blocking proper flow. The records show a reputable service firm had resealed the fuel tanks at the filler cap gasket and excessive caulking had been used. This flaked off and collected in the fuel selector valve. Callback conversation with reporter revealed the following information. Reporter states an FAA inspector who investigated this incident has had a number of problems with silicone. He would like to get out an advisory that silicone is 'bad news' and should be monitored carefully. Reporter most disturbed because the excess silicone was visible at the filler cap and aircraft was inspected so many times with no indication this could be a problem. Reporter had no awareness that silicone flaked off. Previous owner had hired an FBO to remove contaminants from fuel tanks. He must have had some problems with fuel tanks. Mechanics must have seen the flaking yet did nothing. When reporter had inspection after earlier roughness, those mechanics must have seen the flaking. Reporter himself saw little 'sparkles' when fuel was drained, but again did not know those were silicone flakes. Rptrs major concern is that he would like to make pilots aware of this problem so no one else has to experience an emergency landing. Feels he was extremely lucky as it was night, dark and he could barely make out the field. (Had to dodge gopher holes to boot). It was only through his perseverance that the problem was finally diagnosed.

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Original NASA ASRS Text

Title: SMA HAS ENG FAILURE, EMER LNDG.

Narrative: AFTER PURCHASING THE ACFT, AN SMA, ON 5/X/91, I PROCEEDED TO FLY 46 +/- HRS WITH ENG ROUGHNESS ON 2 OCCASIONS. EACH TIME UPON LNDG IT WAS ASSUMED TO HAVE BEEN WATER IN THE FUEL OR CARB ICE. EACH OCCURRENCE HAD ABOUT 40 HRS BTWN THEM. THEN AFTER CRUISING APCHING A 3 HR FLT THE ENG QUIT (ALL PREVIOUS FLTS HAD BEEN 2-2 1/2 LONG). AN OFF ARPT LNDG WAS MADE IN A ROUGH 800-1100 FT HAY FIELD. A MECH THE NEXT DAY COULD NOT FIND THE CAUSE OF ENG FAILURE. ACFT WAS FLOWN OUT AND REFUELED FOR 1 1/2 HR FLT HOME. ALL FUEL SCREENS WERE CLR AND CLEAN. AT HOME PORT THE INVESTIGATION WENT ON. THEN AS A LAST RESORT FUEL FLOW WAS CHKED FROM EACH TANK NOT BOTH. L TANK WOULD NOT FLOW SUFFICIENT FUEL TO OPERATE ENG. TANK FLOWED FREELY BUT NOT PAST FUEL SELECTOR VALVE. THE VALVE WAS REMOVED AND THE L PORT FOUND PLUGGED WITH SILICONE CAULKING BLOCKING PROPER FLOW. THE RECORDS SHOW A REPUTABLE SVC FIRM HAD RESEALED THE FUEL TANKS AT THE FILLER CAP GASKET AND EXCESSIVE CAULKING HAD BEEN USED. THIS FLAKED OFF AND COLLECTED IN THE FUEL SELECTOR VALVE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. RPTR STATES AN FAA INSPECTOR WHO INVESTIGATED THIS INCIDENT HAS HAD A NUMBER OF PROBLEMS WITH SILICONE. HE WOULD LIKE TO GET OUT AN ADVISORY THAT SILICONE IS 'BAD NEWS' AND SHOULD BE MONITORED CAREFULLY. RPTR MOST DISTURBED BECAUSE THE EXCESS SILICONE WAS VISIBLE AT THE FILLER CAP AND ACFT WAS INSPECTED SO MANY TIMES WITH NO INDICATION THIS COULD BE A PROBLEM. RPTR HAD NO AWARENESS THAT SILICONE FLAKED OFF. PREVIOUS OWNER HAD HIRED AN FBO TO REMOVE CONTAMINANTS FROM FUEL TANKS. HE MUST HAVE HAD SOME PROBLEMS WITH FUEL TANKS. MECHS MUST HAVE SEEN THE FLAKING YET DID NOTHING. WHEN RPTR HAD INSPECTION AFTER EARLIER ROUGHNESS, THOSE MECHS MUST HAVE SEEN THE FLAKING. RPTR HIMSELF SAW LITTLE 'SPARKLES' WHEN FUEL WAS DRAINED, BUT AGAIN DID NOT KNOW THOSE WERE SILICONE FLAKES. RPTRS MAJOR CONCERN IS THAT HE WOULD LIKE TO MAKE PLTS AWARE OF THIS PROBLEM SO NO ONE ELSE HAS TO EXPERIENCE AN EMER LNDG. FEELS HE WAS EXTREMELY LUCKY AS IT WAS NIGHT, DARK AND HE COULD BARELY MAKE OUT THE FIELD. (HAD TO DODGE GOPHER HOLES TO BOOT). IT WAS ONLY THROUGH HIS PERSEVERANCE THAT THE PROBLEM WAS FINALLY DIAGNOSED.

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.