What was found
ACFT HAD RT MAIN GEAR UNSAFE INDICATION ON GEAR EXTENSION AT DESTINATION. AFTER FOLLOWING PROCEDURES, CREW WAS NOT ABLE TO ACQUIRE SAFE INDICATION. ACFT LANDED AND AFTER ROLLOUT, ON COMING TO A STOP, THE RT MAIN GEAR COLLAPSED. SIGNIFICANT DAMAGE WAS DISCOVERED TO THE RT MAIN GEAR ACTUATOR SUPPORT STRUCTURE WITH ACTUATOR OBSERVED IN THE EXTENDED POSITION.