What was found
PART (A) OF AD 77-13-21 REQUIRES INSPECTION OF LANDING GEAR EVERY 1000 HRS IAW SL 782. AIRCRAFT EXPERIENCED A COLLAPSED RT MLG FOLLOWING A SCENARIO THAT IS IDENTIFIED IN SL 782. THIS SCENARIO INCLUDES A POPPED LANDING GEAR MOTOR CIRCUIT BREAKER RESULTING IN A FAILED MLG EXTENSION, FOLLOWED BY A MANUAL GEAR EXTENSION. INVESTIGATION FOUND MANY OF THE PARTS IDENTIFIED IN SL 782 WERE WORN AND REQUIRED REPLACEMENT. PART (A) OF THE AD 77-13-21 HAD BEEN COMPLETED 893 HRS AND 12 YEARS AGO. OWNERS AND OPERATORS SHOULD CONSIDER COMPLYING WITH AD 77-13-21 PART (A) MORE OFTEN THAN THE 1000 HRS AS REQUIRED. AD 77-13-21 DOES NOT CONTAIN A CALENDAR REQUIREMENT.