What aircraft was involved and where did it happen?

The accident on 2005-08-15 involved a aircraft, registration OH-LGF, at FI.

What was the probable cause of the accident?

The incident was primarily caused by an error during the installation of the engine's fuel supply line during a recent engine change, compounded by the crew's decision to continue the flight with the leaking engine operational.

Fuel Leak on MD-11 Flight from Helsinki to Beijing

A fuel leak from the left engine of an MD-11 during a long-haul flight led to the loss of 4,000 kg of fuel and prompted an investigation into maintenance and training.

What happened

During a scheduled Finnair flight from Helsinki to Beijing between August 14 and 15, 2005, a fuel leak developed in the left engine of an MD-11, registration OH-LGF. The leak originated from the joint between the engine's fuel supply line and the engine pylon.

Approximately four hours into the flight, the crew received a 'FUEL QTY/USED CHK' alert. Following the Quick Reference Handbook (QRH) procedures, the pilots identified the leak in the left engine but decided to continue the flight to the destination without shutting down the affected engine. During the flight, approximately 2,000 kg of fuel was lost.

Upon landing in Beijing, a strong smell of fuel was noted in the cabin, and the left engine was shut down during taxiing. Ground mechanics confirmed the leak, noting that fuel had splashed onto hot engine components and onto the apron. In total, approximately 4,000 kg of fuel had been lost. The leak was repaired in Beijing, and the aircraft returned to Helsinki normally.

The investigation

The investigation examined the engine replacement performed at Helsinki-Vantaa Airport on June 22–23, 2005. It was established that during this maintenance, the flange of the fuel supply line/pylon joint was left slightly misaligned. This error went undetected during visual inspections and subsequent leak tests. The investigation also reviewed the MD-11's maintenance manuals, the physical design of the fuel line connection, and the flight crew's training programs regarding fuel leak scenarios.

Findings

The primary cause of the incident was an installation error of the fuel supply line during the engine replacement.
A secondary cause was the decision to keep the leaking engine running throughout the flight.
The maintenance instructions for the fuel supply line installation were found to be ambiguous or incomplete.
The design of the joint between the fuel line and the pylon made the misalignment difficult to detect, as the connection is largely obscured by a splash guard.
The splash guard was ineffective at directing all leaking fuel into the collection tray, increasing the risk of fire by allowing fuel to hit hot engine parts.
The flight crew's training and recurrent training had not specifically addressed fuel leak scenarios or the specific procedures for the 'FUEL QTY/USED CHK' alert in recent years.
The crew failed to notify air traffic control of the leak and did not inform the cabin crew in a timely manner.