AOPA Pilot Magazine - October 2012 - 55

LONG-BURNING DESIRE FOR DIESEL
AS WITH MANY ANNOUNCED aviation projects, the SMA engine has been a long time coming. I was at the Paris Air Show in 1997 when Renault, whose racing team engineers developed the engine, announced the project. The then-250-horsepower engine, which was first flown on a Socata TB20, was scheduled to be certified in mid-1998. They then planned to develop 180- and 300-horsepower variants. The project languished through multiple corporate mergers and acquisitions. SMA, a division of the French company Safran, gained STC approval for the Cessna 182 and has had about 50 aircraft flying for several years, collecting data and continuing to refine the design; the engine is already certified in Europe and the United States. Meanwhile, SMA sold the design of that original engine to Continental Motors, which has continued its own refinement process and announced at EAA AirVenture 2012 that three variants of that engine will be brought to market over the next five years. Like Lycoming—a subsidiary of Cessna parent company Textron and the company that will provide support for the SMA engines—Continental has had numerous fits and starts with various diesel projects over the years. The 230-horsepower SR305230E soon to be certified on the 182 is what SMA calls the “enhanced” version of its engine, thus the “E” in the designator. According to Cessna’s Charles Wilcox, the E engine is a culmination of all the learning and improvements that SMA gained from the original engine series. The JT-A is not Cessna’s first foray into the diesel world. In 2007 it announced plans to deliver the 172 with a 155-horsepower Thielert turbodiesel engine. However, in 2008 Thielert filed for bankruptcy and Cessna suspended the program. —TBH
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propeller from Hartzell, the diesel engine installation is about 12 to 15 pounds heavier than the Lycoming. In addition, because Jet A is heavier than avgas, the JT-A fuel weighs 64 pounds more. However, with its significantly lower fuel burn, the JT-A can leave that weight behind in fuel and still fly farther than the avgas-powered model. In fact, Cessna Test Pilot Charles Wilcox reports that the company launched a Turbo 182 and the JT-A together on a 3.2hour round-robin trip. At the end of it, the JT-A top off cost $63 less than the avgas

airplane as a result of the price difference in Jet A and lower fuel burn. In the United States in late August, Jet A averaged about 45 cents a gallon less than avgas—about 8 percent cheaper. In Europe and many other parts of the world, Jet A can be half the cost of avgas. In addition, the SMA engine will likely demand less maintenance. Out of the box its TBO will be 2,400 hours, compared to 2,000 for the Lycoming engine. Wilcox believes the TBO will quickly be lifted to 3,000 hours and ultimately may

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AOPA Pilot Magazine - October 2012

Table of Contents for the Digital Edition of AOPA Pilot Magazine - October 2012