B727 CREW LEFT THE TXWY HARD SURFACE DURING PWRBACK.

Narrative

DURING PWRBACK FROM GATE AB AT MCO; THE ACFT MAIN GEAR ROLLED ONTO AN ASPHALT NON LOAD BEARING SURFACE. PWRBACK WAS DONE WITH MINIMAL PWR AND AT A NORMAL RATE. THE CAPT BEGAN TO COME OUT OF REVERSE EVEN BEFORE THE GUIDE MAN GAVE THE COME FORWARD SIGNAL SINCE WE FELT WE WERE GETTING TOO FAR BACK. SHORTLY AFTER THE COME FORWARD SIGNAL; THE ACFT MAIN GEAR DROPPED OFF ABOUT A 2 INCH SHOULDER ONTO THE NON LOAD BEARING SURFACE. IT CONTINUED TO ROLL ABOUT ANOTHER 10 FT TO A LOW SPOT IN THE ASPHALT IN SPITE OF FORWARD THRUST. ACFT WAS TOWED BACK TO THE GATE AND INSPECTED BY MAINT WITH NO DAMAGE NOTED. IT APPEARED THAT THE GUIDE MAN JUST GAVE THE COME FORWARD SIGNAL TOO LATE TO ALLOW FOR THE NORMAL STOPPING DISTANCE REQUIRED BY A PWRBACK. SUPPLEMENTAL INFO FROM ACN 420750: I FELT A SMALL BUMP LIKE MAIN MOUNT HAD TAXIED OVER SOMETHING. CAPT STOPPED ACFT AND HAD RAMP PERSONNEL TOW ACFT BACK TO GATE. I INSPECTED BOTH MAIN MOUNTS; NOSEWHEEL; AND UNDERSIDE OF ACFT AND FOUND NO DAMAGE. CONTRACT MAINT DID THE SAME. INSPECTION OF THE AREA SHOWED THAT ACFT HAD PWRED BACK OFF CONCRETE RAMP ONTO ASPHALT SHOULDER AREA OVER A 2 INCH LIP. THERE WAS NO DAMAGE TO ACFT. LOGBOOK WAS SIGNED OFF AND FLT RERELEASED. FLT PROCEEDED TO DFW AS PLANNED.