What happened
On 6 August 2003, a Boeing 777-236, registration G-VIIL, was parked at an airport stand in Atlanta, Georgia, following a flight from London. During ground operations, a refuelling operative used a hydrant refuelling vehicle to supply fuel to the aircraft. After connecting two hoses to the refuelling point under the left wing, the operative began the process.
As the automated system reached the pre-set fuel quantity and began closing the aircraft's valves, the operative released the 'deadman's handle' to shut the hydrant valve. At this moment, the refuelling vehicle experienced a sudden lurch. This movement caused the inboard hose to detach from the aircraft, resulting in a spill of approximately 17 litres of fuel onto the apron. There were no injuries and no fire occurred during the incident.
The investigation
An initial engineering inspection in Atlanta revealed that three lugs on the aircraft's refuelling adapter had failed. These broken components were found lodged within the refuelling nozzle of the hydrant vehicle. The investigation also identified that the flexible hoses used by the vehicle were of insufficient length to allow the electro-hydraulic platform to descend fully without tensioning the connection.
A detailed metallurgical analysis conducted in the UK examined the failed adapter and lugs. The laboratory concluded that the failure was caused by excessive stress applied via the refuelling nozzle, which resulted in an overload failure of the lugs. The analysis confirmed there were no pre-existing cracks, manufacturing defects, or material flaws contributing to the break.
Findings
- The primary cause of the adapter failure was an overload of the lugs due to excessive stress.
- The refuelling hoses were not long enough to permit the platform to be lowered completely without pulling on the aircraft's refuelling point.
- The sudden movement (lurch) of the hydrant refuelling vehicle provided the mechanical force necessary to trigger the failure.