SMA PLT HAS ENG SURGES; DECLARES EMER; LANDS DEAD STICK.

Narrative

I WAS CLBING AT 10500 FT ENRTE FROM AUBURN TO DUNSMUIR. THE ENG BEGAN SURGING FROM IDLE TO FULL THROTTLE WITH A PERIOD OF 3-4 SECONDS. DSCNT RATE WAS APPROX 200 FPM. I DETERMINED THAT I COULD REACH CHICO WITH THE ALT I HAD. THE ENG FAILURE CHECKLIST PRODUCED NO IMPROVEMENT IN PERFORMANCE. I WAS ON FLT FOLLOWING WITH ZOA. I INFORMED THE CTLR OF MY SIT AND WAS GIVEN A POS RPT OF 13 MI S OF THE CHICO VOR AND CLRED TO CHANGE FREQ TO CHICO TWR. I DECLARED AN EMER WITH CHICO AND WAS CLRED TO LAND ANY RWY. I BEGAN A DSCNT TO THE W OF THE FIELD. AT ABOUT 6000 FT MSL THE ENG BEGAN TO PERFORM NORMALLY. I DECIDED TO MAKE A NO ENG LNDG SO I COULD DETERMINE THE PROB ON THE GND. I MADE A LNDG ON RWY 13L. THE PROB WAS CAUSED BY THE FUEL SELECTOR VALVE BEING SWITCHED TO 'BOTH' IN CRUISE ABOVE 5000 FT MSL. THE PROB WAS CORRECTED BY DSNDING AND THEN LATER SWITCHING TO 1 TANK ONLY IN CRUISE ABOVE 5000 FT. HUMAN PERFORMANCE FACTORS: THE HUMAN PERFORMANCE FACTORS NEARLY ALL CONTRIBUTED TO A SUCCESSFUL OUTCOME. THE PAX WAS VERY CALM; THE CTLRS I SPOKE WITH WERE ALSO VERY CALM AND PROFESSIONAL. I WAS WELL RESTED; FED AND HYDRATED. THE 95 DEG F TEMP ON THE GND MAY HAVE ADVERSELY AFFECTED PERFORMANCE BY CAUSING AN INCREASE IN SWEAT AND ANXIETY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THE ACFT IS A C172 A 1965 MODEL. THERE WERE A COUPLE OF YRS WHEN THEN ACFT HAD PROBS WITH FUEL LINES NOT VENTING PROPERLY WHEN ABOVE 5000 FT. THERE WAS AN AIRWORTHINESS DIRECTIVE ISSUED WHICH INDICATED EITHER A PLACARD IN THE ACFT OR A FIX. THERE WAS A KIT AVAILABLE. HIS ACFT WAS PLACARDED BUT HE DID NOT COMPLY. RPTR SELECTED A DEAD STICK LNDG BECAUSE HE WAS CONCERNED THAT HE MIGHT SET UP FOR A PWR LNDG AND THEN LOSE THE ENG. HE FELT HE HAD MORE CTL BY ESTABLISHING AN ENG OUT APCH. HE HAD PLENTY OF RWY. THIS WAS ALSO A VERY HOT DAY WHICH HE FEELS MIGHT HAVE ADDED TO THE FUEL LINE PROB.