NEARLY half the light aircraft in Australia have been taken out of service
because of an additive that the oil company Mobil put into one type of aviation
fuel late last year. As 快猫短视频 went to press, there appeared to
be no simple way of getting the planes airborne again.
The grounding is having a devastating effect on the aviation industry. Many
piston-engined aircraft operated by charter companies, flying schools and some
emergency services are unable to fly. The Royal Flying Doctor Service has been
forced to ground six aircraft in its southeast section.
The problem additive is an alkaline chemical called ethylene diamine (EDA).
Mobil spokesman Alan Bailey says his company uses small amounts of EDA to
prevent an acidic catalyst from corroding refinery equipment for making
鈥渁vgas鈥濃�攖he fuel used in piston-engined aircraft. Normally, only traces of
EDA remain in the fuel and have no known effect. But in November, Mobil raised
the level of EDA in response to other changes in the production process. 鈥淲e had
no reason to suppose it would be a problem,鈥� Bailey says.
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Mobil Avgas 100/130 released from the company鈥檚 Melbourne refinery between 21
November and 23 December contained the higher level of EDA. This appears to have
reacted with carbon dioxide in aircraft fuel tanks, and with copper or brass
components in their engines to form sticky deposits that can clog them, causing
them to run roughly and even cut out.
Aviation authorities first became aware of the problem when an aircraft lost
power on take-off from Melbourne鈥檚 Moorabbin airport on 21 December. A sticky
black deposit was found in its carburettor. And on Christmas Eve, after several
further incidents, Australia鈥檚 Civil Aviation Safety Authority (CASA) issued an
airworthiness directive requiring the inspection of piston-engined aircraft for
fuel contamination. Jet and most turbine engines use different fuel and are
unaffected. Last week, a second CASA directive ordered all aircraft potentially
exposed to the contaminated avgas to be grounded until their fuel systems were
replaced or decontaminated. The directive affects about 5000 of Australia鈥檚 11
500 light aircraft, mainly in Victoria, New South Wales and southern
Queensland.
Mobil has developed tests for the contaminant, which CASA must now approve.
CASA hopes the tests can be used to begin to clear uncontaminated aircraft for
take-off by the end of this week. But that is only the first, and possibly the
easiest, stage in dealing with the problem.
Because the EDA deposits are insoluble in avgas, they cannot be flushed out
using clean fuel, as CASA first directed. While the deposits are soluble in
water, that cure may be worse than the disease, says light aircraft pilot Mark
Barnett. 鈥淚f you introduce water into tiny fuel lines, how do you clean it out
again?鈥� he asks. He thinks the only sure way to clean engines may be to strip
them down entirely.
On 18 January, Mobil announced a A$15 million hardship support package
for affected customers鈥攚ith a further programme of compensation to follow
for business losses. Bill Hamilton, president of the Aircraft Owners and Pilots
Association estimates that putting the problem right will end up costing the
industry more than A$100 million.