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and damaging and must be scavenged, and in Avgas the agent that does that is ethylene dibromide (EDB), a chemi¬cal banned by the Montreal Protocol of
1987, signed by every EU country, largely because of its effect on the ozone layer. Unlike car fuel, Avgas must be proven to
Unlike car fuel,
Avgas must be
proven to withstand
rapid and extreme
temperature and
pressure changes
EUR0C0NTR0L / EBAA / IA0PA 2009 93
A sustainable future for aviation >>
environmental improvement. It is expending a
lot of money and effort on better technology"
withstand rapid and extreme tempera¬ture and pressure changes and must pass tests of its ability to remain in storage for long periods.
Much research is going into the provision of alternatives, particularly in the United States. Unleaded Avgas is produced in Sweden and can be used in many lower-powered engines. It is even more difficult to make, achieving the required octane rating without resort¬ing to TEL, mainly by using extraordi¬narily high-quality ingredients and the most stringent quality control methods. Widespread adoption of unleaded Avgas would require duplicated fuel facilities at aerodromes, as leaded fuel would still be needed for higher-performance aircraft.
Diesel engines are being developed to replace Avgas engines - they'd run on jet fuel - but the birth has not been easy. 0ne of the most successful, the Centurion, is produced by the German
company Thielert and drives the Diamond DA42 twin. Thielert recently filed for bankruptcy, a reflection in part of the expense of getting new engines through the regulatory process that ensures they are safe. In theory, lower taxes on Jet-A1 make it economically feasible to re-engine with a diesel and recoup the outlay over
a period of years, although pending changes in the taxation regime in countries like the UK are likely to remove that incentive.
The move towards biofuels is not attractive in aviation. Fortunately, the EU is rowing back on its insistence that biofuel content be increased. An
ethanol derivative called ETBE has some
promise and is being tested in Germany and Sweden.
REDUCING N0ISE LEVELS
Fuel aside, noise is a major environmental concern for aircraft owners. In General Aviation aircraft, the propeller accounts for about half the noise, the engine some¬what less. The European Aviation Safety Agency (EASA) is smoothing out anoma¬lies that prevented some owners from making aircraft quieter. In Germany, for instance, engine silencers have long been mandatory on aircraft like the Cessna 172. In the UK, however, they were illegal, and German aircraft could not be imported without having their silencers removed. EASA certification means they are now legal in both countries and will be more widely adopted.
New propeller designs are coming to market. The propeller makes most noise when tip speeds approach the transonic zone, so a propeller with more, shorter, blades can be quieter.
Martin Robinson, Senior Vice President of the International Aircraft 0wners and Pilots Association, insists: "The industry has an excellent track record of environ¬mental improvement. It is expending a lot of money and effort on better technology and greater efficiency. However, regula¬tors need to be careful not to retard that effort by poorly-targeted taxation and unnecessary stipulation."
GA and Business Aviation may have escaped the general public's attention so far but, like commercial aviation, it has been reducing its negative impact on the environment for decades.
Greener ATM
EUR0C0NTR0L is helping the General and Business Aviation communities, as well as the commercial passenger and cargo sectors to minimise their impact on the environment. Julian Moxon finds out how
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本文链接地址：EUROCONTROL EBAA IAOPA Yearbook 2009: The Business of Flying(44)
