The #2 diesel fuel debate continues

Many times I am surprised by the feedback I get from these columns. Most is positive and greatly appreciated.

Many times I am surprised by the feedback I get from these columns. Most is positive and greatly appreciated.

The little negative feedback I get also is appreciated. It is mostly constructive in that it points out that there is usually more than one side to most discussions. The amount of feedback I got on the Jet A vs. #2 diesel fuel column was much greater than expected. Many comments were from people in northern climates who had struggled with diesel fuel gelling and could not believe anyone would consider trying to use #2 diesel fuel in an airplane.

The part that was disturbing was the tone of the pilots who wanted to use #2 diesel in their diesel cycle Jet A approved aircraft engines. I got the impression that they felt that since they had run #2 diesel in their trucks in the winter they should be able to run it in their airplanes when they got the diesel cycle engines installed. I also got the impression that they felt the FAA had no right to interfere in their flying business.

The FAA does have the right ? and responsibility ? to regulate the fuels that are used in aircraft.

Now I know that here in the USA we like to exercise our personal freedoms by experimenting with new and unusual equipment and combinations of products. However, the FAA has the thankless job of trying to keep these experiments relatively safe with some kind of order. Remember, if an experiment fails in your car you can coast to the side of the road. In aviation, there is that Earth and airplane contact thing that can be dangerous to your health.

So if you wish to use #2 diesel fuel in a diesel cycle Jet A approved airplane engine, there is a procedure to do that. It is called a Supplemental Type Certificate or STC. To get one you must go to the FAA and they will help you set up a program to generate all of the data necessary to obtain the STC. Now here is where most people run into a problem. Most pilots think that since they ran their truck all winter on #2 diesel, they know of a guy who may have used it in an aircraft, and the can of flow improver claims that it will work down to -20?F, that should be enough to get the STC.

The FAA is charged with the task of ensuring that “”good science”” is used for each approval. This means that for each change, statistically significant tests must be run to demonstrate that the change will meet the needs of each application.

When the EAA and Peterson Aviation obtained their STCs for auto gas, they ran a lot of engine tests, hot fuel handling/vapor locking tests, knock tests, plus a whole list of other requirements. This was to ensure that the different fuel met all of the requirements of all of the applications under all types of conditions. Now you can argue that the FAA requires too many tests. But if you are the person signing off on a change that can affect the lives of many pilots, plus the people left on the Earth who might be hit by said aircraft, then maybe to err on the side of caution is not such a bad thing.

Ben Visser is an aviation fuels and lubricants expert who spent 33 years with Shell Oil. He has been a private pilot since 1985. You can contact him at

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