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| **\"Bern, Paul (GE Infra, Aviation, US)\" \<paul.bern@ge.com\>** |
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| 11/19/2007 11:30 AM                                              |
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In response to Docket ID No. OAR-2007-0294.

I am a general aviation pilot and a certificated A&P technician. In
regard to the amount of lead being put into the air by General Aviation
aircraft; First the main fuel used is 100LL. 100 Octane with a very low
amount of lead, hence the \"LL\" (Low Lead). Second, there are not that
many airplanes flying that use this fuel. Go out to any general aviation
airport and you will see that on an average day, you might see 10
airplanes flying in the full course of that day. I doubt very seriously
that your findings will show that the amount of lead being put into the
air by aircraft is beyond or in the danger levels. Most likely the
opposite.

Originally the lead was used to help cool the engines. It made a great
lubricant for the cylinders. Of course after a while, this lead forms an
extremely hard deposit. This deposit in essence damages the engine and
will not allow the engine to go the full length of life. If you remember
back in the 50\'s, 60\'s and 70\'s, automobile engines did not last more
than 50,000 miles. Matter of fact, if your engine did last longer than
that, you were extremely fortunate. The lead was removed from the
gasoline and now, it is not unheard of to see a car engine, if
maintained, go upwards to 300,000 miles.

Another reason for the lead content was the engines that used leaded
fuels had extremely high compression ratios. Today, these engines don\'t
have that much compression. The engines in the airplane that I fly are
260 horse power engines with a compression ratio of 8.6-1. You really
don\'t need all that lead to make this engine run or be safe.
Additionally, you don\'t need all that octane either. Again, look at car
engines today.

Today, there are universities out there experimenting with Ethanol as an
alternative to 100LL aviation fuel. There are some aircraft out there
with Supplemental Type Certificates (STC\'s) that allow the use of this
fuel. Additionally, without the lead, the engines are lasting longer,
running cooler and cleaner as well as running more efficient.

Personally, I am all for getting rid of 100LL fuels. I would like to see
a fuel that did not have the lead in it. If you remove the lead, then
the fuel is cheaper to make, thus keeping down the costs of aircraft
operation. Additionally, less ware and tare on the internal engine
parts.

Below is a link to some of the research that I have spoken of. Of
course, being the EPA, you are most likely aware of what is going on.

Regards

Paul Bern