A BE35 ON A TEST/INSTRUCTIONAL FLT ABORTED ITS FIRST POST MAINT TEST FLT. ON TAXI BACK THE BRAKES BECAME OVER HEATED PREVENTING IT FROM STOPPING SHORT OF THE RWY.

Narrative

THIS WAS THE FIRST FLT AFTER ACFT CAME OUT OF MAINT. THE THROTTLE WAS STICKING SLIGHTLY; BUT SEEMED WITHIN LIMITS AND CONTROLLABLE. ON THE FIRST TKOF RUN; THE DOOR (COPLT'S SIDE) POPPED OPEN AND I INSTRUCTED THE PLT (WHO IS TRANSITIONING INTO THIS AIRPLANE; A BE35) TO ABORT THE TKOF. WE CLRED RWY XXR AT ZZZ; STOPPED; SECURED THE DOOR; AND TAXIED BACK FOR TKOF. UPON REACHING THE HOLD LINE FOR RWY XXR; THE PLT WAS UNABLE TO STOP THE AIRPLANE. (THIS AIRPLANE DOES NOT HAVE BRAKES ON THE COPLT SIDE.) PLT'S L-HAND BRAKE SEEMED TO FUNCTION; BUT PLT'S R-HAND BRAKE DID NOT. WE ROLLED OUT ONTO THE ACTIVE RWY; AND HAD SOME TROUBLE TURNING THE AIRPLANE AROUND TO TURN OFF THE RWY. UPON EXITING THE RWY; THE AIRPLANE CROSSED OVER THE RWY XXR RUN-UP AREA AND WAS PARTIALLY IN THE GRAVEL. WE WERE ABLE TO GET THE AIRPLANE UNDER CTL AND TAXIED THE AIRPLANE BACK FOR MAINT. THERE WERE NO FURTHER INCIDENCES DURING TAXI BACK TO MAINT. UPON SECURING THE AIRPLANE; I CHKED THE HYD FLUID LEVEL AND FOUND IT TO BE FULL. IN MY ESTIMATION; THE BRAKES HAD BECOME OVERHEATED DURING THE ABORTED TKOF. THE ACFT WAS LEFT FOR MAINT AND HAS NOT BEEN FLOWN BTWN THE TIME OF THE INCIDENT AND THE SUBMISSION OF THIS RPT. AS CFI; I ALLOWED THE TRANSITION PLT TO TAXI TOO FAST INITIALLY; I SHOULD HAVE CORRECTED HIM ON FIRST TAXI OUT. I ALSO DID NOT PERSONALLY MANIPULATE THE THROTTLE BUT RELIED UPON HIS JUDGEMENT THAT THROTTLE RESPONSE WAS NORMAL. (THE AIRPLANE HAD BEEN RETURNED TO MAINT AFTER AN EARLIER FLT DUE TO A STICKING THROTTLE.) THE RWY INCURSION WAS MOST PROBABLY DUE TO EXCESSIVE TAXI SPD; POOR LOW-END THROTTLE RESPONSE; OVERHEATED BRAKES FOLLOWING AN ABORTED TKOF; AND NOT TESTING THE BRAKES FOLLOWING THE ABORTED TKOF.