DA20 Flight Instructor with Student; practicing short field landings; reported hitting runway light just before touchdown. Right brake was damaged causing aircraft to depart taxiway after left brake was used to clear runway.

Narrative

The flight instruction topic was short field landings and takeoffs. Before the flight; the student was instructed that to accomplish touching down and landing in the shortest distance possible; a slightly low approach technique would be used. The first approach and landing was accomplished without incident. The second approach was made similarly; and the student claims he intentionally flew a longer downwind. This may have contributed to being slightly lower as indicated by the three red PAPI lights. The student at first raised the nose slightly at about 200 FT AGL; and was instructed to lower the nose back to the original aiming point; the displaced threshold. The airspeed and power settings were appropriate; and the wind was almost direct headwind and less than 10 knots. At about 50 FT AGL; the PAPI showed 4 red lights; but it was determined that we appeared clear of all ground obstacles; so the stable approach was maintained. Crossing the threshold; a crashing sound beneath the aircraft was followed by a glimpse of an object or debris being projected forward. Touchdown was smooth; and student began braking and noted the right brake was not responding. I took controls and used elevator back pressure to help decelerate down the long runway. Once we were at a slow roll; we were able to use left brake to taxi clear of the runway. However; the turn continued left of the taxi line with no right brake. Adding thrust and right rudder was no longer an option as we neared a taxi sign. I tried the right brake again before the left wheel caught the grass and expedited the turn left into the grass; between to taxi lights. The aircraft slowed to a stop in the grass. Initial inspection showed a leak from the right brake and a twisted plate forward of the brake. It is assumed a runway light was struck; waiting for a report from an airport manager. For future flights; corrective action that was discussed during debrief with the student included maintaining a glide path using the PAPI lights.