What was found
(CAN) AFTER LIFT OFF CREW HEARD LOUD BANG AFTER SELECTED LDG GEAR UP. BOTH MAIN GEAR WENT UP & LOCKED INTO POS. NOSE GEAR DID NOT GO UP & NOSE GEAR DOOR IND. LIGHT REMAINED ON. DURING CLIMB OUT SEVERE VIBRATION COMING FROMNOSE OF A/C. AFTER GETTING INSTRUCTIONS FROM TOWER THEY DUMPED FUEL TO LAND UPON RETURNED TO BASE. CREW SELECTED GEAR DOWN, BOTH MAIN GEAR CAME DOWN & LOCKED NORMALLY. AFTER A/C IN BLOCKS INSP CARRIED OUT. THE LT NOSE DOOR ACTUATOR UPPER SUPPORT BRACKET BROKE & SHEARED THROUGH PIN. ACTUATOR ASSY NOW FREE TO MOVE UP & DOWN AS IT STILL ATTACHED TO DOOR. HYD LINES ATTACHED TO ACTUATOR BRACKETS ON NOSE WELL WERE BROKEN OFF .