What was found
REPORTED LOUD BANG WHEN LANDING GEAR EXTENDED. ALL INDICATIONS NORMAL. LANDING NORMAL. AFTER BLOCKING OBSERVED LANDING GEAR DOORS DAMAGED. *S/D* THE CENTER GEAR RETRACT ACTUATOR LOWER BOLT (P/N: AYG7257-1) FAILED. THE CENTER GEAR FREE-FELL AT EXTENSION, DAMAGING THE MECHANICALLY LINKED FORWARD DOORS. THE BOLT, RETRACT ACTUATOR, AND GEAR LUG BUSHINGS WERE REPLACED. INTENSIFIED VISUAL INSPECTION OF GEAR LINKS AND BRACES REVEALED NO ADDITIONAL DAMAGE. A LARGE SECTION OF THE BOLT WAS RECOVERED. FAILURE ANALYSIS REVEALED FATIGUE AS THE CAUSE.