What was found
WHILE PERFORMING A MAINTENANCE SERVICE CHECK 50 HOUR INSPECTION MECHANIC FOUND A BROKEN BLOCKER DOOR (P/N 228-50219-111) ON THE LEFT ENGINE THRUST REVERSER, VISIBLE FROM THE GROUND. FURTHER INVESTIGATION FOUND PROBABLE CAUSE TO BE TWO BROKEN RETURN SPRINGS (P/N 228-50775-101), WHICH CAUSED DOOR NOT TO RETURN IN PROPER SEQUENCE. REMOVED BROKEN SPRINGS AND DOOR, REPLACED WITH SERV PARTS IAW CANADAIR MMC NR 78-33-11 AND 78-33-21.