What was found
LANDING GEAR FAILED TO RETRACT FULLY IN-FLIGHT. ISOLATED ACTUATORS AND FOUND LT MAIN GEAR ACTUATOR BYPASSING (AUDIBLE) FLUID/PRESSURE. DISASSEMBLED ACTUATOR, FOUND DAMAGED AND APPARENTLY INCORRECT (UNDERSIDE) O-RING INSTALLED ON ACTUATOR PISTON. SUSPECT INCORRECT O-RING INSTALLED AT MANUFACTURER (CLEVELAND) DURING ASSEMBLY. SUBMITTER RECOMMENDED ACTUATOR AND AIRCRAFT MANUFACTURERS INSPECT ALL FACTORY STOCK AND SPARES FOR PROPER O-RING INSTALLATION.