C172 PLT FOUND DURING NIGHT FLT THAT THE ROTATING BEACON AND NAV LIGHTS CAUSED A SHORT IN THE ELECTRICAL DRAW. WHEN TURNING THEM OFF; THE ELECTRICAL SHORT WENT AWAY. THEREFORE; HE TURNED ON THE LNDG LIGHT FOR THE 15 MIN REMAINDER OF THE FLT.

Narrative

THIS WAS A NIGHT FLT IN VISUAL CONDITIONS CONDUCTED UNDER VFR. MY ROTATING BEACON AND NAV LIGHTS WERE WORKING FINE WHEN I DEPARTED WESTMORELAND COUNTY ARPT (LBE); PA. LBE IS A CTLED ARPT. ABOUT 1/2 WAY TO MY DEST; FINLEYVILLE ARPT (G05); PA; I STARTED TO HAVE A SIGNIFICANT DISCHARGE IN MY ELECTRICAL SYS AS INDICATED BY THE AMMETER. THE DISCHARGE INDICATION WAS PULSING IN STEP WITH THE FLASHING OF MY BEACON. DURING MY TROUBLESHOOTING OF THE PROB; I FOUND THAT MY BEACON AND NAV LIGHTS WERE CAUSING THE PWR DRAIN. HOWEVER; OTHER ELECTRICAL COMPONENTS INCLUDING THE LNDG LIGHT DID NOT CAUSE A DRAIN. I; THEREFORE; DECIDED TO TURN OFF MY BEACON AND NAV LIGHTS AND CONTINUE THE REMAINING 15 MINS OF FLT USING MY LNDG LIGHT FOR RECOGNITION AND AVOIDANCE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT HE HAS NOT HAD THE LIGHT PROB FIXED SINCE HE HAS NOT FLOWN THE ACFT. HOWEVER; HE HAS DISCUSSED THE PROB WITH MECHS AND WILL HAVE THE PROB FIXED DURING THE ANNUAL INSPECTION. IT IS BELIEVED THAT THERE ARE WIRES SHORTING NEAR THE 2 SWITCHES FOR THE 2 DIFFERENT LIGHTS.