PA28 PILOT STUDENT RUNS LEFT TANK DRY IN TRAFFIC PATTERN AND MAKES EMERGENCY LANDING.

Narrative

THE STUDENT PLT SOLO FLT WAS PLANNED FOR 2.50 HRS OF PRACTICE MANEUVERING AND PATTERN WORK. ACFT WAS PREFLTED BY ME; AND FOUND TO HAVE MORE THAN 17 GALS IN THE L WING TANK (ABOVE THE TAB) AND LESS THAN 17 GALS IN THE R WING TANK (BELOW THE TAB). DUE TO THE UNEQUAL LOAD IN THE TANKS I PLANNED TO RUN THE TANK WITH MORE THAN 2 HRS FUEL IN IT FIRST; FOR 2 HRS. THEN I INTENDED TO RUN THE LOWER TANK WHILE RETURNING TO THE PATTERN FOR LESS THAN 1 HR. DURING MANEUVERING IN THE PRACTICE AREA I SWITCHED FROM THE FULLER TANK TO THE LOWER TANK AT ABOUT 110 MINS INTO THE FLT. I EXPERIENCED SOME ENG ROUGHNESS WHICH WAS NOT CORRECTED BY MIXTURE CHANGES; SO I APPLIED CARB HEAT. I SWITCHED BACK TO THE ORIGINAL TANK AS A PRECAUTION. I RETURNED TO THE ARPT FOR SEVERAL TOUCH AND GO LNDGS AND TKOFS. I WAS ON L DOWNWIND FOR THE ACTIVE RWY BEHIND 2 OTHER ACFT. AS I REACHED MIDFIELD ON THE DOWNWIND LEG; I FELT A DROP IN ENG PWR AND HEARD A DROP IN ENG RPM AND ALSO FELT ENG ROUGHNESS. I RECALLED MY FAILURE TO USE THE SECOND FUEL TANK; SUSPECTED FUEL EXHAUSTION; AND IMMEDIATELY TURNED TOWARD THE AIRFIELD; AS I WAS WELL OUT OVER THE WATER. AS I TURNED I PERFORMED AN EMER PROC CHK OF ALL CTLS. THE ELECTRIC FUEL PUMP WAS ALREADY TURNED ON AND MIXTURE WAS FULL RICH AS I HAD SET THEM FOR REPEATED PATTERN WORK. I MOVED THE FUEL SELECTOR TO THE R TANK. I MADE A CALL TO THE TWR SAYING AS BEST I CAN RECALL: ACFT X REQUEST IMMEDIATE LNDG ENG TROUBLE. THE PROP WAS WIND-MILLING BUT I DID NOT HAVE FULL PWR. I HAD ESTABLISHED AN APCH TO RWY 29 BY THIS TIME AND MADE A CALL SAYING AS BEST I CAN RECALL: ACFT X EMER LNDG. I CONTINUED INBOUND AND ESTABLISHED A STABLE APCH; AND LANDED WITHIN THE FIRST THIRD OF THE RWY. I TAXIED THE ACFT BACK TO THE FBO UNDER THE ACFT'S OWN PWR. INSPECTION REVEALED NO FUEL IN THE L WING TANK.