It’s Time to Eliminate Traditional Filter Monitors
Superabsorbent Polymer (SAP) is a key component in filter monitors that are in standard use across the industry to ensure fuel quality while refuelling aircraft. However, given the accumulated evidence against SAP, the industry recognises the need for new options. In fact, the industry committed to begin phasing out the use of SAP in the refuelling process.1 Immediate and decisive action is needed, even as the industry focuses on recovering from the COVID-19 pandemic.2 At a time when the industry's margin for risk is smaller than ever, is your airline doing enough to mitigate the hidden threats associated with Superabsorbent Polymer (SAP)?
Eliminating the Risks of Refuelling
Shell’s Global Technical & Quality Manager, Rob Midgley, walks through a presentation explaining the risk of using superabsorbent polymer in filter monitors.
Title: Eliminating the Risks of Refuelling
Duration: 6:08 minutes
[Background music plays]
Bright, uplifting music
A three-dimensional model of Earth rotates while white silhouettes of planes fly across the globe. The right side of the screen displays photos of Andreas Schmidt, Rob Midgley, and Vincent Begon.
Eliminating the Risks of Refuelling with Traditional Filter Monitors
Commercial Airlines Manager Europe
Vincent Begon: As the world and aviation are starting to look toward recovery, Shell are hosting a series of webinar on topic which we hope may help our airlines customer during this difficult time to help clear the runway of any obstacle. We would like to get you back in the air where you belong.
Global Quality & Technical Manager
Rob Midgley: We're here to learn about the background of superabsorbent polymers and how Shell has been involved in investigating flight safety related events.
[Animated model showing the path of fuel through a traditional aircraft filter]
The current industry approach
- Two-stage filter monitors remove both dirt and water from fuel.
- Removal of water is critical to safety.
- These filters use SAP, with some amount released downstream into the engines.
Rob Midgley: Most filtration going into wing at the moment is done via filter monitors. The filter is really there as a last chance safety device for fuel going onto the aircraft. We've used this for many years, probably 90% of the aircraft fuellings or more use this type of technology. But we first saw trouble with this back in 2010. It happened after an aircraft refueled in a location called Surabaya in Indonesia. On that flight, the pilot lost control of the engines. This aircraft landed very high speed on a very long runway. So we're very close to having an aircraft loss here. But for the skill of the pilots and the training of the airline itself, we might well have had. So this ended with an investigation to try and understand what happened.
Shell was asked to be involved with this investigation. We were one of the few oil companies that has technical capability to be able to test filters at full scale and full flow rates.
[Animated model showing superabsorbent polymer in the filter, then zooming in to show the superabsorbent polymer as it fills with water and expands, becoming porous]
Rob Midgley: We found that when you get super absorbent polymer wet, then it doesn't just expand and grow, but it also softens in the process. And that makes it problematic when you're looking at filters because filters are designed to hold solid particulates that don't change their form.
[Slide showing bar graph of SAP output per manufacturer tested. Text displays: Filter Monitors SAP Migration Results - After SAP-Mitigation Controls Were Put Into Place]
Rob Midgley: Unfortunately, we then start to see a series of incidents happening within the industry. There was an IATA taskforce that was set up to investigate if there was any link between the presence of superabsorbent polymer and these operational incidents. The conclusion of that work is that we have to remove superabsorbent polymer.
What does it mean for airlines?
Strictly speaking, any fuel that has super absorbent polymer in it doesn't meet the fuel specifications. It's also clear that airlines themselves are responsible for ensuring that fuel meets the specification.
THE OPERATIONAL CHALLENGE: AN AIRLINE’S POINT OF VIEW
Vincent Begon: Now I'll turn it over to our special guest Andreas Schmidt from Lufthansa to give us an airline's perspective.
Manager Jet Fuel Quality
Andreas Schmidt: Fortunately, there are very rare latest investigation reports available, which indicates that SAP contamination was root causing latest events, but there was no actual data available for SAP contamination checks. So there are additional mitigation measures, as it has been said, implemented in the industry, but their effectiveness was not yet proven according to our knowledge.
So we went on setting up our own program and try to see how these mitigation measures were effective or not.
We can conclude I think that real safety issues detected and needs proper mitigation. There is no safe option available besides phasing out filter monitors and we need to act now, play our role. Change can only happen if we all start acting.
Vincent Begon: What I don't understand is why this is still an issue and that no airlines can claim SAP free fueling today. What exactly are the reasons we aren't there yet?
Rob Midgley: It's mainly because there's a large number of the airline inter plane activity is done through filter monitors. The only currently approved alternative to filter monitors is to use filter water separators. It's got a physically much bigger vessel involved with filter water separators. Most vehicles don't have the space to fit them and if they do, you're often exceeding the weight limitations of the vehicles.
So lots of the work that's happened since 2017 is focusing on a solution that fits into the existing vessels. That's where we've done quite a lot of work with Shell jet protection. I'm proud to say that Shell has been involved with developing this alongside FAUDI Aviation and over the past few years.
[Slide showing Shell Jet Protection. Text displays: Developed with FAUDI Aviation, Pending approval by JIG, Most technically mature drop-in solution, Easily fitted into the current refuelling fleet, Sensor constantly assesses fuel for presence of water, Approval anticipated at end of 2020.]
Vincent Begon: That's good to see that there are options for SAP-free fuelling being developed and I'm glad that Shell is also doing its part. Is there any recommendation that you would like to share for them to prepare for these transition for this management of change? Any big recommendation?
Rob Midgley: First of all, the data shows, so coming back to basics of what we're trying to do. The data shows that all filter monitors have the potential to emit superabsorbent polymer, even when operated correctly, and within the bulletin's limitations. So that's point number one.
There's no safe limit for super absorbent polymer within aircraft systems. So the engine equipment manufacturers will tell you that. We must move away from filter monitors. As safety is Shell's number one priority, we're taking that responsibility very seriously and we're investing heavily in this transition and accelerating it.
The second point is that encouraging others to act early, so at least form a transition plan to be SAP free. So this is where we start to need to act together as an industry to drive that aspiration forward. Solutions are appearing that don't require a filter vessel change, and they're starting to become approved. So those conversations and those plans need to be set in place of how operators are going to be removing filter monitors, what time scale, and how is that going to work.
So finally, I think you can act today by working with suppliers at the industry as a whole can be working with airlines, OEMs and suppliers to make sure that we're SAP free and send a strong message to the industry that we need to be incorporating within the decision matrix driven in fuel contracting phase of how to accelerate that transitional process. So only by helping to accelerate the industry do we move to a safer pace more quickly.
[Visual of Shell™ pecten logo]
Contact us at: SAV-Flightpath@shell.com
The views, information, or opinions expressed during this video series are solely those of the individuals involved and do not necessarily represent those of the Shell group of companies and its employees. Shell Aviation has funded the production and recording of this video to drive sustainability conversations in the aviation industry.
It's Time to Eliminate Traditional Filter Monitors and the Risks They Pose
Questions about the safety of SAP first emerged in 2010 when a passenger jet belonging to a major international airline experienced 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 injuries. But the cause was a mystery. Though not involved with the fuelling of the flight, Shell Aviation was asked as an independent expert by an Aviation Regulator and the airline, to investigate the cause of the incident. The team found a possible correlation between the presence of SAP and issues with the fuel-control unit experienced during the flight.
Following a further sequence of incidents, the International Air Transport Association (IATA) convened a Special Interest Group in May 2014 to investigate whether SAP was a factor in these cases as well. Participants included representatives from airframe and engine manufacturers, fuel-filter manufacturers, airlines and airline associations, the Energy Institute, and Shell Aviation, which chaired the group.
No easy solutions
Conventional fuel monitors are designed to capture water and solids from fuel before it's used by an aircraft. They do this by employing a physical filter to catch solid particles and SAP, a material that is also used in disposable diapers, to absorb water. As the IATA investigative taskforce looked into these fuel monitors, they discovered that under certain circumstances, SAP could become saturated and swollen and leak small, gel-like material into fuel. In rare cases, this SAP material can cause significant operational issues in engines. Since 2010, a total of eight incidents have been identified as a result of SAP migration into the fuel and have resulted in issues ranging from a loss of control to in-flight engine failure.3
"We started to see other engine and aircraft types involved, [issues like] heavy surge damage, complete turbine failure, an aircraft that lost its engine on take-off. So really serious stuff," Midgley said.
Filter monitor manufacturers have confirmed it is not possible to guarantee that no SAP will pass downstream in the fuel into the engines. 4And engine manufacturers will not endorse any level of SAP in fuel as "safe." The conclusion: It's not possible to use a filter monitor that contains SAP and be 100% confident that SAP contamination will not happen and will not impact engine performance.5
"We can see from that data that even with the controls that we have in place, existing filter monitors still have the potential to release superabsorbent polymer, Midgley said. "So, when we combine that with no known lower limits (for SAP in fuel), then we must transition away from filter monitors as an industry."
While the solution of replacing filter monitors is straightforward, it is not necessarily easy. Thousands of fuelling systems worldwide employ filter-monitor technology using SAP. The only currently available existing alternative involves the use of water filter separators, which are bulky and difficult to retrofit into existing fleets. Huge challenges loom at the world's largest and busiest airports, whose high-flow hydrant operations mean that new filter water separators would need to be massive and require new vehicles to carry them.6
"The filter water separator is physically a much, much bigger, much heavier vessel. That means that most vehicles don't have the space to fit them. If they do, you're often exceeding the weight limitations of the vehicle. So instead of now changing a filter … you're also changing the vessel. You're also potentially changing the vehicle as well. So that leads into a program of very high cost and very long implementation programs," Midgley said.
In addition to the potential safety risks, the price of postponing action to replace traditional filter monitors could be high. Inaction could impose costs on airlines since engine OEMs have determined that there is no safe level of SAP. Damage determined to be a result of SAP, therefore, may not be covered by OEMs.
"Real safety issues have been detected and need proper mitigation," Andreas Schmidt, Manager of Jet Fuel Quality at Lufthansa, told the webinar. "So, there is no safe option available besides phasing out filter monitors. We need to act now, and each play our role. Change can only happen if we all start acting."
A way forward through industry collaboration
The challenge of transitioning to safer, SAP-free refuelling demanded collaboration across the industry. With this in mind, Shell Aviation and FAUDI Aviation worked together to combine their technical expertise and develop a solution that doesn't use SAP. The result is a technically mature, drop-in solution that replaces the filter monitor with a dirt-defence filter which captures dirt suspended in fuel along with a new and extremely sensitive sensor that continually scans the fuel for water contamination. This system is 100% SAP-free and is called Shell Jet Protection.
The water sensor continually assesses fuel quality and can detect 30 parts per million of water in fuel flowing at up to 7 meters per second. When you're detecting less than 30 parts per million, then it's a very small number. "To put this into context, it is the equivalent of trying to detect and count 270 people in the 9-million-person population of Greater London if they were to all run past you at once. Then that's the sort of level of granularity we're talking about. So, these sensors are quite impressive technology." Midgley said.
If water is detected – a rare occurrence – fuelling of the aircraft is shut down. It detects the water rather than using a chemical to absorb it. The solution is pending approval by the Joint Inspection Group (JIG) and should be available later in 2020.7
"We're at the position now where we're confident that that technology is robust, and the industry as a whole has been working together with field trials to make sure that it operates successfully in the field," Midgley said. "Our intention is to have no filter monitors left in Shell locations where we are under operational control by the end of this year, end of 2020."
Safety is our industry's top priority, and the science is clear: Current filter monitor solutions emit SAP, and there is no safe level of SAP in aviation fuel. By recognising this risk and working together now, the industry can transition away from filter monitors that use SAP to enable safer and more efficient operations.
Ask Shell Aviation
At Shell Aviation, we understand that while the industry is facing various challenges as a result of the pandemic, enabling and maintaining efficient and safe operations will be crucial for Aviation’s recovery.
Today, most aircraft refuellers are fitted with filter monitors that prevent water and dirt particles from getting into the fuel and engine. While water is rarely present in aviation fuel, when it does occur, SAP has been used to prevent it from getting into the aircraft. The aviation industry has committed to phasing out SAP-based water filters used in the refuelling process due to ongoing safety concerns.
If you are concerned about the risks related to refuelling with traditional filter monitors and would like advice from Shell Aviation, please contact us using the contact form. Details of situation and location will dictate the level of support that Shell Aviation may be able to provide. Once your request is received, we will reply as soon as possible. To make it easier for us to assist you, please kindly provide as much information as possible when completing this form.