C5/2005L Passenger aircraft fuel leak during flight on 15 August 2005

On August 14 to 15 2005, between 20.38 and 05.55 UTC, an incident occurred on a scheduled flight from Helsinki to Peking, when fuel started to leak from a joint in the fuel line of the left engine of an MD-11 aircraft. The aircraft, registration number OH-LGF, was owned by McDonnell Douglas Dakota Leasing, Inc and operated by Finnair Oyj. On August 24 2005, in its decision C 5/2005 L, the Accident Investigation Board Finland decided to conduct an investigation into the incident. Investigator Tapani Vänttinen was nominated as chairman and investigator Markus Bergman as a member of the investigation commission.

The left engine of the three-engine MD-11 passenger aircraft had been replaced in June 2005. During the flight fuel started to leak from the engine which had been replaced. The flight was, in spite of the leak, continued to the scheduled destination without shutting down the engine. In Peking the reason for the leak was found, the leaking joint was tightened and the aircraft returned normally back to Helsinki.

The investigation revealed that the instructions used in the installation of the main fuel hose of the engine were partly inaccurate and partly incomplete. Furthermore, the design of the joint between the main fuel hose and the engine pylon was unsatisfactory. In addition, the actions performed by the flight crew in the fuel leak situation were inadequate.

The cause of the incident was primarily an error in installation of the main fuel hose, directly causing the fuel leak, and secondarily the fact that the engine was kept running throughout the flight, in spite of the leak. Other contributing factors to the incident were the inaccuracy of the instructions used in the installation of the main fuel hose, the structure of the joint between the main fuel hose and the engine pylon and the fact that the flight crew had not practised fuel leak situations during training.

The investigation commission issued three safety recommendations. The aircraft manufacturer and the airline should revise the instructions used in installation of the main fuel hose of MD-11 aircraft engines. The aircraft manufacturer should modify the structure of the joint between the main fuel hose and the engine pylon. The airline should review its flight crew training programs to ensure that they adequately prepare pilots for fuel leak situations.

C5/2005L Report (pdf, 0.7 Mt)