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Cessna Skylane. (Cessna)
Cessna Skylane. (Cessna)

The Green Highway

The plane truth about diesel fuel Add to ...

If you’re a doubter who still believe that diesels may be okay for trucks and buses but not for cars, how do you feel about diesel-powered aircraft?

Cessna has announced it’s dropping the turbocharged gasoline piston engine from its popular 182 Skylane and replacing it with a four-cylinder diesel. Cessna says the diesel, from the French company SMA, is 42 per cent more fuel-efficient than the gasoline engine, more reliable and quieter, too.

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Along with cleaner fuel and new diesel technology, mostly from the automotive industry in Europe, new diesels are just as clean as gasoline engines. There’s no doubt that diesel engines with their higher compression ratios produce more power from the same amount of fuel compared to gasoline engines.

However, the main reason Cessna decided to do the switch is because pilots are discovering that leaded avgas (aviation gasoline) is becoming harder to find and might actually be banned some day soon. With a diesel-powered plane, you fill up with jet-A (basically good, old kerosene) which is available at almost any airport and at a cheaper price.

Piston-powered planes these days burn an aviation fuel called 100LL – 100 octane Low Lead. In reality, it’s anything but low lead. It contains more tetraethyl lead than most of the automotive grades of leaded fuel before it was phased out. Environmental groups have been calling for the elimination of leaded aviation fuel for years.

It’s interesting that Cessna is marketing its new diesel plane as “jet-A powered” while barely mentioning diesel at all. It’s still fighting the perception widespread in the United States that diesels are dirty, noisy and smelly. In Europe, where more than half the new cars are diesel, consumers know better.

I flew a Cessna 172 for a few years long ago. Even then, I longed for a diesel-powered plane when I tallied up the horrendous fuel costs. When you’re dragging all that aluminum through the air you’re lucky if you’re getting 10 or 12 miles per U.S. gallon of 100LL. Diesels with their superior torque, longer TBO (time before overhaul) and better fuel burn seemed to be the way to go. The problem was diesels needed turbocharging and the turbo didn’t do you much good when you were in thinner air at higher altitudes. That’s been fixed now with better turbos.

I read a review of a flight test in Flying magazine and the pilot loved the diesel performance, just as I had always expected. The engine that Cessna is using is from SMA, a company which began as a joint venture involving Renault. Diesels play a huge role in the products of auto makers like Renault and I think the diesels or “jet-A powered” will become just as important in general aviation.

If they’re good enough for airplanes they ought to be good enough for cars and there are signs diesel cars are becoming more mainstream. While diesels are more than 50 per cent of new cars in Europe, they’re between 1 and 3 per cent in North America. Volkswagen sells the most followed by Mercedes-Benz.

General Motors has announced it is going to start selling a diesel-powered version of the popular Chevrolet Cruze in 2013. There is also supposed to be a diesel version of the Cadillac ATS in the near future. Mazda hasn’t made the announcement, but it has hinted heavily that diesels will soon be available in its most popular model, the Mazda3.

But it’s still the “perception” issue that’s holding diesel back. When many people think diesel, they think of dirty black carbon pouring out of a truck or bus – not a sweet-sounding aircraft engine with nary a trace of smoke.

As the Obama administration’s proposed 54.5 mpg fleet-wide fuel economy standards come into effect by 2025 (unless elections prove otherwise), diesel cars are going to be more necessary. So if you’re not ready for a diesel car yet, then go try a diesel Cessna. Push the throttle forward, pull back on the yoke and feel the smooth power pulling you skyward. How bad is that?

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