C150 PLT ATTEMPTS CONTACT WITH RBD TWR PRIOR TO DEP WITHOUT SUCCESS UNTIL TURNING ONTO RWY; WHEN CHALLENGED BY TWR.

Narrative

I FLEW CESSNA 150 INTO RBD TO PICK UP REPAIR PARTS. THE TWR WAS OPERATING AND ALL WAS NORMAL IN THE ARR. THE PARTS HAD NOT ARRIVED AT THE ARPT AND THERE WAS A DELAY. WHEN THE PARTS ARRIVED WE WERE IN A HURRY TO GET BACK. WE LOADED THE PLANE AND CALLED THE TWR. THERE WAS NO ANSWER. I CHKED THE FREQ AND CALLED SEVERAL MORE TIMES WITH NO ANSWER. AFTER SEVERAL MINS CALLING WITH NO ANSWER; I TUNED TO A VFR ADVISORY FREQ AND VERIFIED THE RADIO WAS OPERATING NORMALLY. I SWITCHED BACK TO TWR AND CALLED AGAIN. I TURNED THE ACFT TO FACE THE TWR AND COULD SEE NO ONE IN THE TWR. I CALLED SEVERAL MORE TIMES AND DECIDED THAT THE TWR MUST HAVE CLOSED. I SHOULD HAVE LISTENED TO ATIS BUT MY BRAIN REFUSED TO THINK OF IT. I ANNOUNCED MY INTENTIONS TO TAXI TO THE RWY AND GOT NO REPLY. ON MY WAY TO THE RWY; I CALLED SEVERAL MORE TIMES WITH NO RESPONSE. I PERFORMED MY RUN-UP; CALLED TWR ONE LAST TIME WITH NO RESPONSE; PULLED UP TO THE HOLD LINE; CHKED FOR TFC; AND ANNOUNCED MY DEP AS CUSTOMARY FROM AN UNCTLED FIELD. AS I RELEASED THE BRAKES THE TWR CALLED AND INQUIRED HOW I GOT THERE AND DIDN'T I KNOW I COULDN'T DEPART WITHOUT CALLING THE TWR. RBD IS NOT A BUSY ARPT. NO OTHER ACFT MOVED ON THE ENTIRE FIELD OR CALLED TWR DURING THIS ENTIRE EXCHANGE. I BELIEVE THE CTLR WAS PROBABLY THE ONLY PERSON ON DUTY AND HE MAY HAVE TAKEN A NECESSARY BREAK. WHEN THE CTLR ASKED HOW I GOT TO THE RWY; I TOLD HIM I HAD BEEN TRYING BUT COULDN'T GET AN ANSWER. TWR IMMEDIATELY CLRED ME TO DEPART AND I LEFT WITHOUT FURTHER PROBS.