The demise of 100LL is no surprise

At the recent AOPA Aviation Summit, several industry leaders made the startling comment that lead in avgas is going away. Well, duh, what do you think I have been saying for the last 20 years?

The comments fall into three general areas: The first is the gloom and doom group that feel that it is all over and that we should just scrap all of the planes and have everyone in GA go find a new hobby to dump money into. The second group is in denial — they do not believe the EPA will actually go through with its threat to outlaw leaded fuels. And the third group believes that someone will come up with a miracle fuel that will replace 100LL, cost less, and perform better in all applications.

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Global warming debate stifles progress

I’ve received a lot of mail on my recent column on the effects of carbon dioxide on global warming (How are planes affecting the environment?). The replies were both pro and con on global warming and the greenhouse gas thing.

I read most of the reports and find them very interesting. The problem is in the raw data of temperatures in a given area or areas. If one looks at the average temperature over an extended period of time — like for as long as they have been keeping records — the data looks very confusing.

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Jet A and diesel engines

In a previous column I talked about going to a recent ASTM meeting and the progress being made on unleaded avgas. At this same meeting, there also was a lot of discussions on the qualification of diesel cycle aircraft engines on Jet A.

There were two main areas of discussion: The first was to establish a recommendation on how to certify these engines; while the second was a report that several oil companies are telling their dealers not to sell Jet A to aircraft owners with diesel engines because of liability concerns.

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The fuel of the future

As all pilots know, you go to Oshkosh to find out what is new in aviation. But if you want to know what’s new in aviation fuels, you go to an ASTM meeting.

ASTM is the organization that is in charge of the specifications for just about everything. If you buy a gallon of Jet A almost anywhere in the world, it will be certified to meet the ASTM D-1655 specification requirements. Likewise, if you buy a gallon of 100LL, the list of tests and the limits that the fuel must meet are defined by the ASTM D-910 specification.

The other part of this is if you have an aircraft that is certified on 100LL specification fuel, you must use only fuel that meets this specification, or use a fuel that has been STC’d for your aircraft.

This means that if a new unleaded fuel is introduced, an ASTM specification must be created to “define” what the new fuel is and what specifications it must meet.

So what is the industry working on?

No surprise, it is working on a specification for a 94 minimum lean rating fuel that looks a lot like the present 100LL fuel, only without the lead.

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Oil temperature vs. oil viscosity

Reader David Bennett recently wrote in, asking about oil temperature vs. oil grade.

“When oil is rated for a certain temperature range, is that start-up temperature range or the range for most of the intended trip? My Super Cub handbook states SAE 40 is good from 30°F to 90°F, but on the Aeroshell site, it says 0°F to 70°F. Which is right?”

Temperature vs. oil viscosity is important at both start-up and cruise. If the oil is too thick at start-up, it will increase the time from when the engine first turns to when oil reaches critical wear surfaces. This can increase the wear rate and reduce engine life.

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How are planes affecting the environment?

Lately, I’ve received a lot of e-mails from readers asking about the environment and the effect of internal combustion engine exhaust on our climate.

One factor is the effect of CO2 on the environment. My understanding is that CO2 is relatively harmless and naturally occurring.

To try to better understand the latest concern about CO2, I contacted a couple of “experts” who work in the environmental area. I found the answers fascinating and wanted to share them, but when I asked permission to quote them, the answer was absolutely NOT. When I asked why, they answered that they are in the research business and do not want to risk losing a grant from either side of the problem.

In other words, “what answer do you want?” has replaced “what is the correct answer?” as the guide for doing research.

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Getting the lead out

I received an e-mail from a gentleman who is a “small investor” in Swift Fuels, a group associated with Purdue University working to produce an unleaded, high-octane aviation fuel that can be made from almost any sugar-containing plant matter.

He asked that I update people on Swift’s progress, as well as took me to task for my past statements questioning some of their figures and conclusions.

First, an update. Swift Fuels has continued to test its product in engines at its facility, at the FAA test lab and at the manufacturers. It also has begun flight evaluations. As I understand it, the fuel has met all of the octane requirements and has performed well in all tests to date. I applaud their efforts and feel that they are doing an excellent job and wish them the best.

I do however have a few problems with the program.

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What oil should you use?

Many pilots want to know what oil to use and where to get it.

To answer these questions accurately, I sent a questionnaire to the four main oil companies that supply lubricants to the general aviation industry. I received nice replies from Shell and Phillips, a note from BP that said the company was changing personnel and that they would get back to me, and an e-mail from Exxon that said that everything is on its website (

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Six tips to cut your flying expenses

Frugal flying may be some sort of oxymoron, but there are a number of things pilots can do to minimize expenses.

The first and foremost is to maintain your engine and keep it on spec. A fouled spark plug or retarded mag timing can increase your fuel consumption significantly.

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