Narrative:

Aircraft was an small aircraft with carburetor for automatic gas. None used in 4 yrs. Aircraft left for 4 days with 3/4 tanks. No water at preflight. 5 min flight with top off with 100 octane 10.6 gallons (aircraft calls for 80/87). Takeoff climb for 25 min to 10000 MSL (freeze level 15000). Normal lean procedures in level cruise 5-10 min when engine starts to surge. First a little then from windmill, 1500 RPM. Carburetor heat pulled. First trim for best glide. Trouble shoot. First fuel from both to right tanks then across panel from left to right. Deep in mountains, no good landing spots. Tried pumping primer, engine picked up first couple of strokes. Mixture rich and carburetor heat on. At this time, 7000 ft. No restart. Below peaks following valley for time. Everything gets cycled, ie, carburetor heat mixture anything that moves. 30 seconds after surge I did call mayday on 121.5 and reached whidbey NAS radio. They handed me off to seattle approach. At 5400 ft switched to left tank restart. Asked for radar vectors to nearest airport and landed. Aircraft run very well now on either tank which scares the hell out of me. I've grounded it until we come up with some answers! 2 requests: that high altitude emergency procedures be discussed with all pilots. In hindsight I realized I had a real rich mixture with carburetor heat and full mixture. Callback conversation with reporter revealed the following information. Reporter stated that the aircraft was bought used and did not have any placard referencing fuel tank selection or use to a published FAA air worthiness directive (ad). Ignorance of a ruling being no excuse, reporter further stated that the problem was a fuel vent situation with his aircraft fuel caps not being vented properly as the referenced ad was not known or available. This design problem that affects smas from 1963 to 1972 models creates a vapor lock and the fuel management technique suggested is that the pilot operator is to use only 1 tank (left or right) at a time above 5000 ft. Reporter was using both selection when event occurred. The ad came out after the mfr's service letter. There is a service kit available (not known to reporter) that will vent the fuel caps properly. The problem with the ad is that operating on 1 tank at a time does not solve the problem, it just allows the air to be adjusted within the opposite non used tank prior to it's use so as to preclude a vapor lock. Kit costs $180.00. Reporter felt that the local FAA office wanted to make an issue of this but didn't. FAA knows of this condition as does the mfr but many pilot owners do not. Reporter further noted that some small aircraft type aircraft such as this have the ad posted by fuel selector but he feels that this is not too noticeable for average perceptive pwrs to take note.

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Original NASA ASRS Text

Title: SMA PLT GETS A FLT ASSIST AND RADAR VECTORS TO NEAREST ARPT AFTER HIS ENG EXPERIENCES AN INFLT SHUTDOWN STOPPAGE.

Narrative: ACFT WAS AN SMA WITH CARBURETOR FOR AUTO GAS. NONE USED IN 4 YRS. ACFT LEFT FOR 4 DAYS WITH 3/4 TANKS. NO WATER AT PREFLT. 5 MIN FLT WITH TOP OFF WITH 100 OCTANE 10.6 GALLONS (ACFT CALLS FOR 80/87). TKOF CLB FOR 25 MIN TO 10000 MSL (FREEZE LEVEL 15000). NORMAL LEAN PROCS IN LEVEL CRUISE 5-10 MIN WHEN ENG STARTS TO SURGE. FIRST A LITTLE THEN FROM WINDMILL, 1500 RPM. CARB HEAT PULLED. FIRST TRIM FOR BEST GLIDE. TROUBLE SHOOT. FIRST FUEL FROM BOTH TO R TANKS THEN ACROSS PANEL FROM L TO R. DEEP IN MOUNTAINS, NO GOOD LNDG SPOTS. TRIED PUMPING PRIMER, ENG PICKED UP FIRST COUPLE OF STROKES. MIXTURE RICH AND CARB HEAT ON. AT THIS TIME, 7000 FT. NO RESTART. BELOW PEAKS FOLLOWING VALLEY FOR TIME. EVERYTHING GETS CYCLED, IE, CARB HEAT MIXTURE ANYTHING THAT MOVES. 30 SECONDS AFTER SURGE I DID CALL MAYDAY ON 121.5 AND REACHED WHIDBEY NAS RADIO. THEY HANDED ME OFF TO SEATTLE APCH. AT 5400 FT SWITCHED TO L TANK RESTART. ASKED FOR RADAR VECTORS TO NEAREST ARPT AND LANDED. ACFT RUN VERY WELL NOW ON EITHER TANK WHICH SCARES THE HELL OUT OF ME. I'VE GNDED IT UNTIL WE COME UP WITH SOME ANSWERS! 2 REQUESTS: THAT HIGH ALT EMER PROCS BE DISCUSSED WITH ALL PLTS. IN HINDSIGHT I REALIZED I HAD A REAL RICH MIXTURE WITH CARB HEAT AND FULL MIXTURE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. RPTR STATED THAT THE ACFT WAS BOUGHT USED AND DID NOT HAVE ANY PLACARD REFERENCING FUEL TANK SELECTION OR USE TO A PUBLISHED FAA AIR WORTHINESS DIRECTIVE (AD). IGNORANCE OF A RULING BEING NO EXCUSE, RPTR FURTHER STATED THAT THE PROBLEM WAS A FUEL VENT SITUATION WITH HIS ACFT FUEL CAPS NOT BEING VENTED PROPERLY AS THE REFERENCED AD WAS NOT KNOWN OR AVAILABLE. THIS DESIGN PROBLEM THAT AFFECTS SMAS FROM 1963 TO 1972 MODELS CREATES A VAPOR LOCK AND THE FUEL MGMNT TECHNIQUE SUGGESTED IS THAT THE PLT OPERATOR IS TO USE ONLY 1 TANK (L OR R) AT A TIME ABOVE 5000 FT. RPTR WAS USING BOTH SELECTION WHEN EVENT OCCURRED. THE AD CAME OUT AFTER THE MFR'S SVC LETTER. THERE IS A SVC KIT AVAILABLE (NOT KNOWN TO RPTR) THAT WILL VENT THE FUEL CAPS PROPERLY. THE PROBLEM WITH THE AD IS THAT OPERATING ON 1 TANK AT A TIME DOES NOT SOLVE THE PROBLEM, IT JUST ALLOWS THE AIR TO BE ADJUSTED WITHIN THE OPPOSITE NON USED TANK PRIOR TO IT'S USE SO AS TO PRECLUDE A VAPOR LOCK. KIT COSTS $180.00. RPTR FELT THAT THE LCL FAA OFFICE WANTED TO MAKE AN ISSUE OF THIS BUT DIDN'T. FAA KNOWS OF THIS CONDITION AS DOES THE MFR BUT MANY PLT OWNERS DO NOT. RPTR FURTHER NOTED THAT SOME SMA TYPE ACFT SUCH AS THIS HAVE THE AD POSTED BY FUEL SELECTOR BUT HE FEELS THAT THIS IS NOT TOO NOTICEABLE FOR AVERAGE PERCEPTIVE PWRS TO TAKE NOTE.

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.