C172 PLT HAS SHORT TERM PWR LOSS ON FINAL APCH DUE TO MISPLACEMENT OF FUEL SELECTOR VALVE.

Narrative

ABOUT 20 MINS INTO PATTERN WORK AND ON THE DOWNWIND LEG JUST BEFORE TURN TO BASE; I DECIDED TO GO THROUGH THE GUMPS CHK (FOR THE FIRST TIME SINCE TKOF AS I WAS TRYING TO REMEMBER TO WORK THIS INTO MY ROUTINE) AND NOTICED THAT I HAD NOT PLACED THE FUEL SELECTOR VALVE FROM 'R' TO 'BOTH' AT TKOF. I INADVERTENTLY TURNED THE VALVE OFF INSTEAD OF TO 'BOTH' AND AS I WAS TURNING ONTO BASE ABOUT A MI FROM THE THRESHOLD; THE ENG QUIT. I IMMEDIATELY SET UP FOR BEST RATE OF GLIDE (65 KTS) AND TURNED DIRECTLY TO THE THRESHOLD. I WAS CONCERNED THAT I MIGHT NOT HAVE ADEQUATE ALT AND STARTED TO LOOK FOR A GOOD EMER LNDG SPOT. SEEING NONE; DUE TO THE STEEPNESS OF THE TERRAIN BEFORE THE RWY THRESHOLD AND FORESTED LANDSCAPE; I IMAGINED THAT THIS WAS NOT GOING TO BE PRETTY. THIS THOUGHT MADE ME REVIEW THE CTL SETTINGS STARTING WITH MAGNETOS; IGNITION; THROTTLE; MIXTURE; OIL PRESSURE AND TEMP AND THEN FUEL SELECTOR VALVE. I SAW THAT I HAD PUT THE SELECTOR VALVE IN THE 'OFF' POS WHEN I DID THE GUMPS CHK. I HAVE HAD DIFFICULTY IN THE PAST DETERMINING THE R INDICATION OF THE VALVE AND THIS WAS COMPOUNDED BY THE DIM LIGHT IN THE CABIN AT DUSK. I PUT THE VALVE IN THE 'BOTH' POS AND THE ENG ROARED TO LIFE. I COMPLETED THE LNDG SAFELY AND CONTINUED IN THE PATTERN FOR ANOTHER 40 MINS. IN REVIEWING THE EVENTS THAT LED UP TO THIS EVENT I REALIZED THAT I HAD FAILED TO FOLLOW THE ENTIRE CHKLIST THROUGH TO COMPLETION (BOTH ENG START-UP AND BEFORE TKOF). THIS WAS DUE TO THE FACT THAT I WAS FRUSTRATED AND RUSHED. I HAD LOST 45 MINS OF TIME; BUT DID WANT TO GET IN THE FLT TIME. ONCE I WAS IN THE PLANE; I EXPEDITED MY EFFORT TO GET AIRBORNE. WHILE I DID PERFORM A THOROUGH PREFLT; THIS DID NOT CARRY OVER INTO THE COCKPIT.