SMA ON INITIAL CLB HAS HIGH VOLTAGE LIGHT FLICKERING AND AMMETER NEEDLE FLUCTUATING. AFTER RETURN LAND TAXIES ACROSS ACTIVE RWY WITHOUT CLRNC.

Narrative

I TOOK OFF ON AN IFR FLT PLAN FROM HEF (MANASSAS; VA) TO FRG (FARMINGDALE; NY). THE WX WAS CLR. UPON CLBOUT AND AFTER REACHING APPROX 3000 FT; I NOTICED THE HIGH VOLTAGE LIGHT FLICKERING. THE AMMETER NEEDLE WAS FLUCTUATING AT THAT TIME AS WELL; AND I NOTICED A HISS IN THE RADIOS. I NOTIFIED ATC OF THE PROB AND REQUESTED RETURN TO THE FIELD AT HEF. DURING MY VISUAL APCH TO HEF; THE CTLR ASKED WHICH RWY I WANTED AND WHETHER I NEEDED ASSISTANCE. I BELIEVE THAT I STATED THAT I WAS PARKING ON THE W SIDE BUT REQUESTED 34R (THE RWY ON THE E SIDE) BECAUSE IT WAS LONGER. AFTER LNDG; THE CTLR CLRED ME FOR TAXIING TO THE E RAMP. HAVING BEEN CONCERNED; HOWEVER; ABOUT THE HIGH VOLTAGE PROB; I CONTINUED MY TAXI TO THE W RAMP. THIS INVOLVES XING 34L; A PARALLEL RWY. AS IT WAS EARLY IN THE MORNING; THERE WAS NO TFC AND THE CTLR DIDN'T SAY ANYTHING. I STATED MY APOLOGIES AND THE GND CTLR CLRED ME FOR TAXI TO THE W RAMP. THE NEXT TIME; I'LL TRY TO STATE MY INTENTIONS MORE CLRLY AND TRY TO LISTEN MORE INTENTLY; THOUGH IT WILL BE VERY DIFFICULT AFTER PROB SITS OCCUR.