PA28 PLT HAS A GND CONFLICT WHILE TAXIING AT OAK.

Narrative

I RECEIVED CLRNC TO TAXI FROM THE FUEL FACILITY ON OAK N FIELD COMPLEX TO 'OLD T'S': 'TAXI TO OLD T'S; HOLD SHORT OF RWY 15; RPT HOLDING SHORT.' WHILE A SPECIFIC RTE WAS NOT GIVEN; THE IMPLIED IS TAXI VIA TXWY D. NO OTHER WARNINGS; CAUTIONS OR 'HOLD SHORT OF' INSTRUCTIONS WERE GIVEN BY THE GND CTLR.' ABOUT HALFWAY ON TXWY D I SUDDENLY SAW AN R22 HELI HOVER 2-3 FT ABOVE THE TXWY DIRECTLY IN FRONT OF ME. I VEERED L AND BRAKED TO A STOP. UPON NOTICING MY ACFT STOPPED BUT CLOSE BY; THE R22 HOVERED TO A POINT OFF THE TXWY AND LANDED. BOTH ACFT CAME TO ABOUT 30 FT FROM HITTING EACH OTHER. I DID NOT NOTICE THE R22 UNTIL VERY CLOSE TO IT. THE HELI BLENDED IN WITH THE LARGE HANGARS BEHIND IT AND ITS ROTATING BEACON; WHILE WORKING; WAS INITIALLY SHIELDED BY THE ROTOR. MY ACFT WAS TAXIED ON THE CTRLINE OF TXWY D. THE R22 WAS HOVERING ABOVE A DESIGNATED HELI LNDG SPOT ON THE SAME TXWY. I NOTIFIED GND CTL OF THE CLOSE CALL AND AWAITED INSTRUCTIONS. GND CTL STATED THE HELI WAS ON A DIFFERENT (TWR?) FREQ AND TOOK A MOMENT TO COORDINATE WITH THE OTHER CTLR. AFTER A SHORT DELAY THE HELI DEPARTED FROM THE POINT OFF THE TXWY AND I WAS INSTRUCTED TO PROCEED. THIS CLOSE CALL COULD HAVE BEEN PREVENTED BY BETTER COORD BTWN GND AND TWR CTLRS. 'CAUTION HELI IN HOVER TAXI ON SAME TXWY D' OR 'HOLD SHORT OF (SOME POINT/INTXN ON THE TXWY)' INSTRUCTIONS WOULD HAVE PREVENTED THIS. ALTERNATIVELY DESIGNATED HELI LNDG SPOTS COULD BE MOVED OFF OF TXWYS.