Over the years I’ve flown around a dozen varieties of the Cessna 182, from the latest glass-panel turbo models to impeccably restored early birds, but I’d never experienced anything like this. As I advanced the single black lever in Cessna’s new 182 JT-A to roll around the corner onto 19L at Wichita’s iconic Mid-Continent Airport, I felt a smooth surge of power.
If I hadn’t known that there were four big pistons up front, beating their way up and down inside a beefy metal case, I’d have thought this thing was jet powered. I advanced the short-throw power lever smoothly and reveled in the smooth rush of power, and we were off. At 55 knots we were flying; I stowed the flaps, pointed the nose upward and just listened.
As we climbed out through the impossibly clear and hot Kansas day, I couldn’t help but think of all those Cessna 182s, those tens of thousands of sheet metal birds that had rolled off the line these past 50-odd years, and I knew I was hearing something different, a sound that would very likely be the future of light GA. It’s the sound of a piston compression engine. That’s right: a diesel.
In Oshkosh, Wisconsin, in late July, Cessna announced that it would replace its T182T turbo Skylane in favor of a model that burned jet-A. The new model, at first dubbed the 182 NXT but now referred to as the 182 JT-A, is on track for certification early next year with deliveries by the middle of the year.
The decision by Cessna to not only introduce a diesel model but also to discontinue the turbocharged gas piston version speaks volumes about the confidence that the Wichita manufacturer has in the new engine and its new partner, SMA. It was a bold business decision, but that confidence seems to have already begun to pay off in orders from North American and overseas customers.
Why Diesels, Why Now?
For the past couple of decades, there have been high hopes for the future of aviation diesel-engine technology. Today, the technology’s future seems especially bright, in part because everyone agrees that the future of 100LL, our current avgas, looks so dim. The Environmental Protection Agency, which regulates contaminants (but not airplanes, luckily), hasn’t announced just when it will pull the plug on 100LL, but it could happen at any time, and there’s no telling how long the agency would give us to make the transition.
Diesel engines, which historically have been regarded as dirty, loud, sooty and inefficient, are getting better in just about every way imaginable. Today’s automotive diesel engines are clean, powerful and remarkably fuel-efficient. A couple of engine manufacturers, Thielert (now Centurion Engines) and Austro (a sister company of Diamond Aircraft), have leveraged automotive diesel engine technology into aviation diesels that are certified and flying on hundreds of airplanes, though all has not gone smoothly. The Thielert engines famously suffered from early and severe reliability woes, largely due to issues with their accessories, mainly their gear box.
While the search is on for an unleaded avgas alternative, it doesn’t look like a short process. There are no early favorites and no clear timeframe for the adoption of a new standard avgas. Cost issues, moreover, are complicating the matter. While in North America 100LL is easy to find and no more expensive than jet-A, in some parts of the world, low-lead avgas is difficult or impossible to find; we’ve heard reports of 100LL costing as much as $20 per gallon. Jet-A, on the other hand, is available worldwide.
While it’s not realistic to expect that owners are going to replace their gas piston engines en masse with diesels, new-production airplanes outfitted with diesel-technology engines are a natural next step and will doubtless achieve great popularity in many parts of the world where it’s hard to get or afford 100LL but where jet-A is at nearly every airport.