Cleaner engines take to the skies
22 Jan 2001
Shell Aviation, together with KLM Royal Dutch Airlines and BetzDearborn, has commenced a flight trial of a jet fuel performance-enhancing additive. The trial aims to demonstrate that using the additive in jet fuel can provide both environmental and economic benefits to commercial aviation.
The high temperature dispersant/detergent chemistry performs a similar function to that which has been featured for many years in automotive gasoline and diesel fuel additives. The companies expect that the flight trial will demonstrate similar performance benefits in the turbine engines used in commercial aviation. The patented liquid additive is designed to keep fuel and injector systems clean, reducing exhaust emissions, improving fuel efficiency and lowering maintenance costs.
The additive being used for the KLM trial was designed by BetzDearborn during a US Air Force research and development programme to develop a fuel with enhanced thermal stability. Of hundreds of additives tested, it was the only one to progress through engine tests, flight trials and into service.
Improvement in the thermal stability significantly reduces the tendency of the fuel to degrade and to form deposits, lacquers and coke in the hot areas of the engine fuel system. By keeping fuel spray nozzles clean and preventing coking, more efficient combustion is promoted, with resultant reduction in coke deposits and thermal stress in the combustor, turbine and afterburner (in military aircraft) areas.
BetzDearborn, which developed and manufactures the additive, markets the product in North America; Shell Aviation markets the product in the rest of the world. KLM is the world's first commercial airline to trial the product.
The trial will involve two KLM Boeing 747-400 aircraft powered by GE CF6-80 engines. Shell Aviation and KLM Refuelling Services have arranged injection of the additive into the fuel supplied to these aircraft at Amsterdam's Schiphol airport and several other airports in Asia. The trial is expected to last for a period of twelve months.
During the trial, KLM will use its aircraft monitoring systems to evaluate the effects of the additive on aircraft performance, and will conduct periodic borescope inspections of the combustion chambers and fuel nozzles, looking for greater cleanliness.
