For many years, the standard system used across the world was known as a filter monitor, which used Superabsorbent Polymer (SAP) to prevent water and dirt particles from getting into the fuel and engine.

Questions about the safety of SAP first emerged in 2010 when a passenger jet belonging to a major international airline experienced severe engine trouble, causing it to lose thrust control and land at twice the normal speed. Thanks to the skill and training of the aircrew, this resulted in no deaths or serious injuries, but the cause was a mystery. Though not involved with the fuelling of the flight, Shell Aviation was asked to investigate the cause of the incident as an independent expert. The team found a possible correlation between the presence of SAP and issues with the fuel-control unit experienced during the flight.

A number of subsequent incidents were linked to SAP, although thankfully none of them ended in an accident. In May 2014, the International Air Transport Association (IATA) convened a Special Interest Group in to investigate whether SAP was a factor in these cases as well. Chaired by Shell Aviation, this group included representatives from airframe and engine manufacturers, fuel-filter manufacturers, airlines, airline associations and the Energy Institute.

It was discovered that, under certain circumstances, SAP particles could be released from the filter and into the fuel. In rare cases, these particles move into the aircraft during fuelling and can cause significant operational issues in engines. The very system designed to protect the aircraft from fuel contamination had the potential to cause contamination itself. Manufacturers of filter monitors confirmed that it was not 100% possible to guarantee that SAP particles would not migrated into the aircraft and, as a result, the IATA Special Interest Group concluded that filtration systems using SAP should be phased out.

In 2015, Shell began working with leading filtration specialists FAUDI Aviation to find a safe replacement for the SAP based filter monitors. The result was Shell Jet Protection. This new system replaces the current filter monitor elements with Dirt Defence Filters and a separate AFGUARD® Electronic Water Sensor (EWS). By using this EWS, extensively tested by Shell and qualified to EI1598, the system can continuously monitor the refuelling process. It safely turns off the fuel flow to the aircraft on the rare occasions when water is detected. After testing and field trials, the system was accepted for use by the Joint Inspection Group in August 2020.

A major benefit of Shell Jet Protection is that it can be easily retrofitted into existing fuelling vehicles, avoiding costly fleet replacement. In addition, Shell Jet Protection extends the life span of the mechanical filter element resulting in less waste per annum. Also, as the new system does not include non-biodegradable SAP, no non-degradable waste is released into the environment. Shell Aviation successfully rolled the system out to its entire fleet of refuelling trucks at all Shell-operated locations worldwide by the end of 2020, well ahead of the date recommended by industry regulators. The benefits of this safety initiative are not restricted to Shell, the system is available to anyone within the industry wishing to move away from filter monitors.

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