
Watch: The next generation of fuel filtration
As the aviation industry looks to return to the skies, ensuring that aircraft are fit to fly after being parked for an unprecedented amount of time is no easy task. Alastair Hobday, Fuel and Lubricants Specialist for Rolls-Royce, discusses challenges facing the world of jet fuel and emerging filtration technologies.
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As the industry eyes a return to growth, part of the new normal will be a renewed emphasis on sustainability, Hobday said, adding that Rolls-Royce is tackling its environmental impact by focusing on three main pillars: more efficient engines, sustainable aviation fuel, and hybrid electric and alternative solutions.
The next generation of fuel filtration
Title: The Next Generation of Fuel Filtration
Description:
Aviation industry expert Mike Farmery interviews Alastair Hobday, Fuel and Lubricants Specialist for Rolls-Royce. Alastair will share his perspective on issues such as the need for SAP-free fuel filters, the role of technology in driving operational improvements, the need for industry collaboration in achieving sustainability goals, and the issue of microbial contamination.
Duration: 5:56
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The Shell™ pecten logo appears, then fades. A three-dimensional model of Earth rotates while white silhouettes of planes fly across the globe. On the right side of the screen, a shot of Alastair Hobday talking with no audio.
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This episode: The Next Generation of Fuel Filtration
{Mike Farmery sits onscreen. Facing him is Alastair Hobday. The camera alternates between speakers.}
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Mike Farmery
Aviation Fuel Consultant
Founder, Clear and Bright
Mike Farmery:
Hello, my name’s Mike Farmery, and today, I’m talking with Alastair Hobday, the fuel and lubricant specialist for Rolls-Royce, about some of the challenges facing the world of jet fuel.
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Alastair Hobday
Fuel and Lubricants Specialist
Rolls-Royce
Mike Farmery:
Alastair, tell us where we are today.
Alastair Hobday:
Hi, Mike. Today, we’re in the preparation shop, next to our ultra-large testbeds in Derby, where we prep the engines ready for test before they go out to the customers.
Mike Farmery:
So, we’re going to hear a few offsite noises today, I think. Obviously, it’s been a very tough time for your customers over the last year or so, but as the recovery gets underway, what are the conversations you are having with your customers, and what are you hearing from them about some of the fuel-related challenges they’ve been facing?
Alastair Hobday:
One, relates to how many aircraft have been parked up for an unprecedented period of time. We’ve never had so many aircraft with our engines on the ground for so long. Clearly, returning those aircraft and engines safely to service is a big challenge – making sure that from a fuel and a fuel system perspective, those aircraft and engines are fit to fly.
At the time of the pandemic beginning, we did have in the industry two quite significant events associated with one of the biocides that is approved for use. Those biocides limit the formation of microbial material and help to keep the aircraft systems in an appropriate manner. Because one of those biocides was no longer available, that did limit the options for the operators. So, we had to ensure, working closely with our operators and our customers, that they followed very closely the engine and airframe manuals to ensure that it was limiting the amount of water in the aircraft.
Mike Farmery:
Could you tell us what superabsorbent polymer is?
Alastair Hobday:
Yes. We use superabsorbent polymer in the into-plane refueling equipment on airfield and airports. It essentially does a very effective job of removing water that’s entrained in fuel to ensure we put dry, clean fuel onto the aircraft.
Superabsorbent polymer itself is what you find in baby’s diapers. So, it does a great job of absorbing large amounts of water, and essentially swelling when it absorbs. And by doing so, with it being constrained in a filtration element, it thereby stops the fuel flow. So, if you expose these SAP filters to a large amount of water, they can effectively hard-stop fuel flow at quite high pressure.
Mike Farmery:
From your perspective, what has been the technical problem with superabsorbent polymer?
Alastair Hobday:
So, superabsorbent polymer is a great technology. It’s protected the aircraft systems and engines very well over the last few years, and it does work very well, provided it's maintained and operated completely in accordance with the manufacturer’s instructions. However, in certain instances where those procedures aren’t followed properly or where maybe contaminated fuel is put through the systems, it can lead to some of that polymeric media migrating downstream into the aircraft and engine systems. The engine systems in particular are quite intolerant of this type of material, and it can cause fuel-system control problems.
Jet fuel is one of the few things on an aircraft that has the source of being a common-mode failure. We have a single supply of fuel onboard the aircraft in the wings, and if that fuel is contaminated, it has the potential to cause problems in both engines at the same time, and there aren’t many things where that scenario can occur. So, hence, if we’ve got problems with fuel quality as a result of superabsorbent polymer in the filters, it has the potential to hurt both engines, and we need to address that issue urgently from the safety perspective.
Mike Farmery:
I understand as a result of that, the engine manufacturers, you included, have sort of said that they want to move to an SAP-free world in the future.
Alastair Hobday:
There’s a real urgency for the airlines to move away from this type of SAP technology as it does represent a safety flight risk, and the airlines are ultimately responsible for the quality of fuel that goes into the airframe. We, as engine manufacturers, have a zero-tolerance policy for superabsorbent polymer in the fuel. So, fuel that is going into the aircraft that contains this polymeric material is not fit for purpose.
Mike Farmery:
The industry is doing a huge amount of work trying to find alternative filtration technologies. What sort of feedback are you getting from your customers about that challenge, and what do they think about what’s going on?
Alastair Hobday:
Yeah, I think one of the big challenges, Mike, is the communication side of it. So, some customers are very aware. Lots of customers aren’t as aware. I think it’s incumbent on us and the rest of the industry to work together in a collaborative way to ensure that everyone is aware of the risks and the challenges around using SAP media and the urgency to move to an alternative technology.
Mike Farmery:
You, in Rolls-Royce, use thousands of sensors on your engines, and one of the new technologies in filtration uses a sensor to help protect against water contamination. What’s your view on the use of sensors in fueling systems?
Alastair Hobday:
In our engine systems, we use many, many thousands of sensors to do different roles, and anything that can, again, help to inhibit water coming onto the aircraft has got to be a great thing. So, recognising we move away from a SAP-type filtration system to a different system that might well need a water sensor. Now, if you’ve got water-sensing technology, maybe other technologies, it gives us information around fuel quality, fuel properties, then absolutely. That’d be a great thing, and potentially we have systems on the engine that can then react to those particular properties and attributes of the fuel going forward. That is certainly a possibility.
Mike Farmery:
Thank you very much, Alastair.
Alastair Hobday:
Thank you, Mike.
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As the aviation industry looks to return to the skies, ensuring that aircraft are fit to fly after being parked for an unprecedented amount of time is no easy task, according to Alastair Hobday, Fuel and Lubricants Specialist for Rolls-Royce.
“We’ve never had so many aircraft with our engines on the ground for so long,” Hobday said in an interview with aviation fuel expert Mike Farmery. “Returning those aircraft and engines safely to service is a big challenge.”
When the pandemic grounded thousands of planes worldwide, aviation fueling experts were faced with the possibility of widespread microbiological contamination of fuel, which can happen when water finds its way into fuel tanks and when the fuel stagnates for long periods of time, Hobday said. Microbial contamination can cause significant operational issues for aircraft and, in extreme cases, even require defueling of an aircraft, an expensive and complicated procedure.
Issues with one of the biocides used to treat fuel further complicated the situation, according to Hobday. With limited biocide options available, the team at Rolls-Royce worked closely with operators and customers to ensure they were closely following engine and airframe manuals to limit the amount of water in the aircraft.
“I think the positive message we are hearing now is that we’ve heard very few major problems in terms of safe service return,” said Hobday.
Now, the aviation industry faces a new challenge as it phases out the use of superabsorbent polymer (SAP), a key component in filter monitors in standard use across the industry to ensure fuel quality while refueling aircraft, due to ongoing safety concerns.
Under certain circumstances, SAP particles can escape the filter and enter the fuel. In rare cases, this can cause significant operational issues in engines. While the industry has agreed to stop using SAP-based filters, many airlines and operators have yet to begin the transition to new technologies, Hobday said.
“There’s a real urgency for the airlines to move away from this type of SAP technology as it does represent a safety risk,” said Hobday. “We, as engine manufacturers, have a zero-tolerance policy for superabsorbent polymer in fuel. So, fuel that is going into the aircraft that contains this polymeric material is not fit for purpose.”
One solution is new filtration technology from Shell Aviation that uses a sensor to detect minute amounts of water in fuel and then shuts off the flow into an aircraft.
As the industry eyes a return to growth, part of the new normal will be a renewed emphasis on sustainability, Hobday said, adding that Rolls-Royce is tackling its environmental impact by focusing on three main pillars.
“One is around more efficient engines, the other is around sustainable aviation fuel (SAF). The third is around hybrid electric and alternative solutions,” said Hobday. “But from a jet fuel perspective, certainly sustainable aviation fuel is a really important topic that’s occupying a lot of time in Rolls-Royce.”
Rolls-Royce recently carried out a successful test flight of a jet using 100% SAF in one of its engines. The test was an important milestone to demonstrate safe commercial use of SAF, which currently must be blended at a maximum 50% with conventional jet fuel.
Hobday said the test also demonstrated the kind of successful partnership between aircraft manufacturers, engine makers, fuel producers, and other stakeholders to help scale SAF as the industry seeks to mitigate the impact of its emissions.
“There’s no way that one individual company will fix this. There’s a massive challenge in terms of availability of product as we go out to 2050 in people’s net-zero targets,” said Hobday.
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