BONANZA PLT HAS ENG MALFUNCTION DURING APCH TO ILL AND ELECTS TO DO AN OFF FIELD LNDG.

Narrative

DEPARTED ZZZ1 TO ZZZ2. PRE-LNDG CHKLIST HAD FUEL ON L MAIN; MIXTURE RICH AND ENTERED DOWNWIND AT 45 DEGS FOR RWY 28; GEAR DOWN; 15 DEG MANIFOLD PRESSURE. BEGAN L BANK TURN TO BASE. ENG LOST PWR AS I GAVE MORE THROTTLE AND NO RESPONSE. A QUICK CHK OF FUEL SELECTOR VERIFIED L MAIN AND NO ENG RESPONSE. ALT WAS APPROX 500 FT AGL. AT THE END OF RWY 10 IS A DRAINAGE DITCH. I KNEW I WAS NOT GOING TO MAKE THE RWY AND HAD PWR LINES AND TREES TO CONTEND WITH. I FEATHERED THE PROP AND RETRACTED THE FLAPS. CLRED THE TREES AND LANDED IN A BEAN FIELD APPROX 1/8 MI FROM THE ARPT. NO DAMAGE TO THE ACFT OR MYSELF. UPON INSPECTION; FUEL SELECTOR WAS ON L MAIN AND VISUAL INSPECTION SHOWED TANK TO BE 3/4 FULL. ACFT R FUEL VENT WAS CLR. THE L VENT WAS SLIGHTLY BLOCKED AND WAS BLOWN OUT. ACFT WAS TOPPED OFF AND TOOK 47 GALS. 63 GALS USABLE MEANT 16 GALS WERE IN THE L MAIN. TEMP AT THE TIME WAS UPPER 30 DEGS. THE MECH HAD NO SOLID EXPLANATION. ICE MIGHT HAVE BEEN A POSSIBILITY OR THE PARTIALLY BLOCKED L VENT. THE ACFT WAS CHKED OUT; MAGNETOS; VENTS; RUN-UP; ETC; AND FLOWN HOME THE SAME DAY. THE ACFT HAD A CHK VALVE REPLACED DUE TO FUEL LEAKAGE 6 MONTHS PRIOR. IT HAD NOT BEEN A PROB SINCE THAT TIME. WE ARE GONG TO CONTACT THE BONANZA ORGANIZATION FOR THEIR THOUGHTS ON THIS SIT.