BE24 WITH BRAKE FAILURE TAXIES INTO PARKED ACFT AT GAI.

Narrative

BEFORE ENG START-UP; STUDENT TESTED BRAKES. HE SAID THEY FELT MUSHY. I TESTED THE BRAKES. THE R BRAKE FELT MUSHY; BUT DID NOT TRAVEL ALL THE WAY TO THE FLOOR. IT FELT LIKE WE HAD BRAKES. AFTER START-UP THE STUDENT TESTED BRAKES BEFORE TAXIING. THE BRAKES WORKED. THE STUDENT ADDED A LITTLE PWR TO START THE AIRPLANE MOVING; REDUCED PWR; AND APPLIED BRAKES. THE BRAKES WORKED. THE STUDENT ADDED PWR AND TURNED TO THE L TO BEGIN TAXIING. THE AIRPLANE MOVED FORWARD ABOUT 20 FT AND THEN BEGAN TURNING TO THE L. HE STATED THAT HE HAD NO R BRAKE AND THE R RUDDER WAS STICKING. HE REDUCED PWR TO IDLE. I REDUCED THE MIXTURE TO IDLE CUTOFF AND APPLIED BRAKES. THERE WAS NO RESPONSE FROM THE R BRAKE. THE PROP STRUCK A PARKED C172 ON THE C172'S L SIDE COWLING. WE TURNED OFF THE MASTER; MAGNETOS; AND FUEL SELECTOR. WE THEN VACATED THE ACFT. I CHKED THE BRAKES AND SAW THAT THE OUTBOARD BRAKE PAD ON THE R BRAKE CALIPER WAS MISSING. THE STUDENT; A 500 HR PVT PLT; SAID HE HAD CHKED THE BRAKES AND THE BRAKE PADS DURING THE PREFLT INSPECTION AND THOUGHT THEY LOOKED OK. I DID NOT VERIFY THAT THE BRAKES WERE PRESENT BEFORE ENG START-UP.