TEMPORARY LOSS OF ACFT CTL IN LNDG PROC ROLLOUT BRAKING ACTION. ACFT EQUIP DESIGN PROBLEM.

Narrative

THIS WAS AN ACFT CHKOUT IN AN SMA CONCURRENT WITH A BIENNIAL FLT REVIEW I WAS GIVING. PEOPLE HAD ALWAYS WARNED ME ABOUT THE STRENGTH AND PEDAL GEOMETRY OF THE BRAKES. THE PEDALS ARE POSITIONED SO THAT IT IS EASY FOR AN INEXPERIENCED PLT TO BE ON THE BRAKES AND THINK HE'S ON THE RUDDER. THIS WAS THE STUDENT'S SECOND LNDG IN TYPE. ON TOUCHDOWN; I COULD HEAR AND FEEL THAT THE STUDENT WAS ON THE BRAKES. I ASSUMED HE WAS EXPERIMENTING WITH HVY BRAKING TO SEE HOW RAPIDLY WE COULD DECELERATE. I HAD BRIEFED HIM ON THE BRAKES IN THIS ACFT. AS WE CONTINUED THE LNDG ROLL; I STARTED TO HEAR THE L TIRE SQUEALING. I STARTED TO OPEN MY MOUTH TO TELL HIM TO LIGHTEN UP ON THE BRAKES; WHEN I HEARD A BANG; AND THE NOSE STARTED YAWING TO THE L. I TOOK CTL; AND TOOK THE NEXT L INTXN. WE SHUT DOWN ON THE TAXIWAY WELL CLR OF THE RWY. THIS WOULD NOT HAVE HAPPENED IF I HAD NOT ASSUMED HE KNEW WHAT HE WAS DOING. HE HAD ABOUT 175 HRS AND WAS A COMPETENT PLT; JUST UNFAMILIAR WITH THE TYPE. THIS ALSO COULD HAVE BEEN AVOIDED IF I WERE MORE AGGRESSIVE IN THE SITUATION. I SHOULD NOT HAVE HESITATED TO 'CALL HIM OFF' THE BRAKES.