The project

On 17 January 2008 a Boeing 777 owned by British Airways and flying from Beijing to London landed short of the runway while arriving at Heathrow airport. There were no fatalities but the aircraft was written-off.  The accident was investigated by the Air Accidents Investigation Branch (AAIB) and a final report was issued in 2010. Ice crystals in the jet fuel were blamed as the cause of the accident, clogging the fuel-oil heat exchanger (FOHE) of each engine and restricting fuel supply to the engines

As a result of this accident WEC was requested to investigate the risk of this event occurring on a client aircraft type, and to quantify the icing “threat” to the engine, so that the engine could be tested to verify flight safety.

• The project required a large diverse team of engineers, researchers and academics, working closely together, in order to understand the icing phenomenon and to develop new certification verification methods to ensure continued airworthiness of the aircraft.
• WEC engineers developed an innovative testing strategy, identifying the key test variables that could lead to ice accretion within the fuel system. This enabled an estimate of the worst-case volume of ice that could be present in the fuel during aircraft operations.
• WEC engineers were responsible for developing a strategy report and test rig requirements along with preparation of the test requirements, supporting rig build and commissioning. WEC engineers also conducted the tests alongside the client’s team.
• Testing began with the evaluation of ice accretion variables on short test sections of the fuel system using a research rig, before proceeding to develop new test methods and procedures on a full-scale aircraft fuel system replica. Appropriate environmental conditions were applied during the investigation in order to mimic the key parameters that would be experienced during flight.
• Mechanisms of ice release were also investigated in order to understand how and when ice, that may have accreted within the fuel system, could be dislodged and fed to the engines and in what quantity.
• On completion of the testing WEC engineers analysed the results, wrote the test reports and prepared the compliance documentation for the certification authorities.