A Lufthansa Airbus A330-300, registration D-AIKD performing flight LH-444 from Frankfurt/Main (Germany) to Atlanta,GA (USA), was enroute at FL340 about 50nm northwest of Dublin (Ireland) when the crew requested to return to Frankfurt reporting a technical issue, they were okay to return Frankfurt, no priority or assistance was needed. The aircraft descended to FL330 for the return, the crew subsequently advised they were having a fuel leak, they did not need to declare PAN. The aircraft landed safely on Frankfurt's runway 07R about 155 minutes after turning around. A passenger reported the crew announced they "didn't have enough gas to cross the Atlantic". A replacement Airbus A330-300 registration D-AIKM departed three hours after landing back and reached Atlanta with a delay of 6.5 hours.