State-Of-The-Art Real-Time Jet Fuel Quality Measurement

State-Of-The-Art Real-Time Jet Fuel Quality Measurement

Jed B. Stevens, Greg Sprenger, Miles Austin
DOI: 10.4018/978-1-60960-887-3.ch005
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This chapter discusses the historical approaches to monitoring aviation fuel quality, and the current industry movement towards continuous monitoring electronic measurement systems. The application of mature technology from other industries is reviewed and found to be inadequate. A new type of sensing system designed specifically for the needs of aviation fuel quality is introduced, showing advanced user features and proven to be far more accurate than any other method current available. This article also discusses a typical problem in real world applications where a combination of contaminant is encountered, and how only the new type of sensing system can properly measure the contamination to aviation fuel quality specifications.
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History: Ensuring Jet Fuel Quality

From the beginning of Sir Frank Whittle’s jet engine, fuel quality has been very critical to safe flight. The kerosene-based fuel used in the evolving jet engines has also evolved. From the original illuminating kerosene Whittle used, to the various modern fuels of today, quality assessment has changed as well.

The current commercial fuels are largely covered by two major specifications: ASTM D1655 and DEFSTAN 91-91 (ASTM. Standard Specification for Aviation Turbine Fuels. D1655-05, 2007), (Ministry of Defence (UK). Turbine Fuel, Aviation Kerosine Type, Jet A-1. Defence Standard 91-91, Issue 6, 2008). These specifications cover an extensive variety of requirements for these fuels, from bulk properties, such as boiling point range, to trace properties, such as flash point. In addition, contamination is considered in properties such as surfactant (surface active agent) levels, dissolved metals, particle content and water content and more recently issues such as cross-contamination with other petroleum products.

Once the fuel leaves the refinery, the two main contaminants of concern are solid particles and free water. This contamination ingression takes place primarily during transportation of the fuel and also during fuel storage, before the fuels are burned. The presence of these two physical contaminants is detrimental to aircraft fuel systems and engines, and compromises flight safety. Acceptable levels have been specified; however current methods of assessment in the field have not evolved to keep up with aircraft and engine improvements.

In fact, the most accepted measure of fuel quality at the aircraft is still the “Clear and Bright” test, which is a subjective, visual examination of the fuel taken into a white bucket. The tester examines the bottom of the bucket for any contamination that settles (IATA. Guidance material for aviation turbine fuels specifications, Part III Cleanliness and handling, 5th edition, 2004). Obviously, the vision of the tester and the lighting conditions have a large effect on the capability of actually finding contaminants.

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