What was found
FLT 713 FROM BOS TO ROC, AFTER TAKEOFF AND CLIMBING, THE RIGHT MAIN GEAR DOOR LIGHT REMAINED ON. CYCLED THE GEAR AND THE LIGHT REMAINED ILLUMINATED. AN EMERGENCY WAS DECLARED AND THE AIRCRAFT LANDED WITHOUT INCIDENT IN BOS. ON POST FLIGHT INSP NOTED THAT THE RIGHT MLG SIDE STRUT DOWN LOCK ROD WAS BROKEN. REMOVED AND REPLACED RIGHT MLG SIDE STRUT DOWN LOCK ROD, PERFORMED GEAR SWING AND OPS CHECKS NORMAL. NO OTHER DEFECTS NOTED. AIRCRAFT WAS RETURNED TO SERVICE.