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-   -   Bio-fuels and commercial aviation (https://www.pprune.org/tech-log/632711-bio-fuels-commercial-aviation.html)

Sriajuda 23rd May 2020 09:17

Bio-fuels and commercial aviation
 
So, SLF here. Did a bit of flying, ok. But I have some expertise in other areas. So I have an urgent question to the people who truly know the answer (please no speculations - that's my part):

Is jet fuel (Kerosene) also mixed with "bio-fuel" as in Diesel here in the EU?

If so, that could be extremely dangerous with planes sitting on the tarmac for months, in the baking heat, presumably with not-emptied tanks.
I am an avid sailor, very well connected in the sailing community, and since they started mixing the bio-fuel into the Diesel, we have had a virtual explosion of problemes from this. What happens? Sailboats use their engines quite sparingly. Mostly only for harbor maneuvers. In winter storage, the fuel has ample time to develop bacterial growth. This growth produces large, slimy clots of stuff that can easily block a 1/2 inch fuel line, not to mention filters and injectors. And that is during the *cold* season.

Has anyone looked into that possibility? Because, if my suspicion is right, there are tens of thounands of aircraft sitting on tarmacs that might be ticking time bombs, as flight restrictions are lifted!

Thanks to anybody in the field who can contribute to this question, and possibly raise the alarm.

George, from Germany
This post has been moved from the recent Karachi crash thread to the Tech Log as it really isn't talking about the crash itself, but rather a question regarding the specifics of modern jet fuel. If it is too far out in left field it can certainly be closed.

Bluffontheriver123 23rd May 2020 09:23


Originally Posted by Sriajuda (Post 10790650)
So, SLF here. Did a bit of flying, ok. But I have some expertise in other areas. So I have an urgent question to the people who truly know the answer (please no speculations - that's my part):

Is jet fuel (Kerosene) also mixed with "bio-fuel" as in Diesel here in the EU?

If so, that could be extremely dangerous with planes sitting on the tarmac for months, in the baking heat, presumably with not-emptied tanks.
I am an avid sailor, very well connected in the sailing community, and since they started mixing the bio-fuel into the Diesel, we have had a virtual explosion of problemes from this. What happens? Sailboats use their engines quite sparingly. Mostly only for harbor maneuvers. In winter storage, the fuel has ample time to develop bacterial growth. This growth produces large, slimy clots of stuff that can easily block a 1/2 inch fuel line, not to mention filters and injectors. And that is during the *cold* season.

Has anyone looked into that possibility? Because, if my suspicion is right, there are tens of thounands of aircraft sitting on tarmacs that might be ticking time bombs, as flight restrictions are lifted!

Thanks to anybody in the field who can contribute to this question, and possibly raise the alarm.

George, from Germany

George, donít worry this has nothing to do with bio-fuel. Imagine trying to park your car in your garage and trying to brake from 100kph with about 40m to go. How would that turn out? That is how far out of the slot the first approach was....

Sriajuda 23rd May 2020 09:38

Do you positively know there are no bio-fuels added to jet fuel? All over the world?? Would be relieved to hear that. But, please, only if you truly *know* that this is the case.

Denti 23rd May 2020 15:23

There are some very limited test flights with bio fuels. But in normal operation biofuels are not added to jet fuel.

That said, even in normal Jet-A1 you can get bacterial or algae growth. Which is one of many many reasons why airplanes either have to be carefully stored, or parked with continuous maintenance requirements including engine runs and maintenance continuation flights. In the airline i work for they have to fly latest every 30 days, which currently is done empty as either maintenance reposition flight to an airport with cheaper parking fees or just a departure, vectors back for an approach and landing at the same airport.

john_tullamarine 24th May 2020 01:38

As the previous poster indicated, biological contamination is, and has been for a long time, a major concern with fuels and fuel storage.

However, the OP's question is reasonable and, I have no doubt, there will be a few fuel technical specialists in the sandpit who might like to offer comment from a specification and straight technical side of the table. At the end of the day, we might all learn a bit more about the dark world of fuel specs.

Dave Therhino 24th May 2020 05:28

The specification for Jet A and Jet A-1, ASTM D1655, requires the fuel to be produced from petroleum stock. Biofuel has been used for some test programs and approved in-service demonstrations, but it is not used in the production of normally used Jet fuel.

The industry is very aware of the potential for biological contamination to build up with airplanes in storage, and has sampling, control programs, and cleaning processes defined in the aircraft maintenance manuals. In fact, there is an issue currently being worked with one of the major biocide products, Kathon FP 1.5, that is causing extra attention to this subject at this time.

PJD1 24th May 2020 22:33

As others have said there is no bioethanol / FAME (fatty acid methyl ester) in jet fuel, the specification for Jet A1 allows for a maximum of 5ppm (0.0005%) FAME. The issue of micro-bacterial growth in fuel is nothing to do with the presence of bioethanol, it is a known and well documented issue with all middle and light distillate fuels and can occur at the interface between fuel and water at the bottom of a storage tank, all fuels contain some water and in storage this will separate out and collect at the bottom of the tank.

The production and supply of aviation fuel is a highly regulated and quality controlled process and the fuel is tested at every point in the supply chain to ensure it meets the relevant specifications. There are well established aircraft maintenance and storage procedures in place that will ensure that the fuel in any aircraft not being used will be safe so I can assure you that there is no ticking time bomb here (and no speculation, I have 20+ years of experience working for a major fuel company in the aviation fuel sector :) )

tdracer 24th May 2020 23:21

I know there is a great deal of work going into producing viable bio-Jet A - one particularly promising method based on using a feed stock derived from algae.
That being said, the production of bio Jet A is far different than what goes into bio-diesel and the like. A Dave T notes, there have been several test flights and feasibly demonstrations using bio Jet A, but we're still a ways from widespread adoption of its use.
I don't know enough about to know if bio Jet A retains meaningful amounts of bioethanol or FAME, but I do know that the people working the issue know that they need to address the issue of biological growth in bio fuel as it's stored.

PJD1 25th May 2020 06:54


Originally Posted by tdracer (Post 10792416)
I don't know enough about to know if bio Jet A retains meaningful amounts of bioethanol or FAME, but I do know that the people working the issue know that they need to address the issue of biological growth in bio fuel as it's stored.

As I said in the post above the maximum amount of FAME in Jet A1 is 0.0005%. The "issue" of micro biological growth has been around ever since we started using and storing hydrocarbon fuels in the early 20th century and is not specific to fuels containing FAME, it is well understood and there are well established procedures in place to ensure that it does not cause any problems in the fuel supply chain.


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