9:28 AM

Diesels in Our Future?

Each time we see another article about leaded AvGas going the way of the dinosaur, many of us immediately think about a day when small but powerful aircraft engines without spark plugs will push us through the sky. These small wonders would burn diesel fuel, which is not that far removed from Jet A.

Until just recently, diesel aircraft engines such as those manufactured by Thielert Aircraft Engines of Germany represented our best hedge to cover our bet if/when 100LL is ever pulled out of production. Yes, small turboprop engines might one day be an option too for GA aircraft, but that is quite a leap from what we have today. With diesel engines as our one realistic alternative to current avgas powerplants, it is really bad news that we read this from AOPA's web site:

"After three years of investigation, suspicions about the financial health of Thielert Aircraft Engines (TAE) have culminated with the company’s filing for bankruptcy, the termination of founder Frank Thielert as chief operating officer, and a renewed criminal investigation against both Thielert and management board members. While TAE has appeared to be a successful company, having bought Texas engine manufacturer Superior Air Parts, secured deals with American unmanned aerial vehicle (UAV) manufacturers, and recently signed on to supply Cessna Aircraft with its 2.0-liter Centurion turbodiesel engines for its 172 Skyhawk line of piston singles, the company’s burn rate (negative cash flow) had raised suspicions since 2005."
Thielert's Centurion line is such an exciting product, it had won the approval of Cessna's mighty engineering team, which does not enter into any agreement without significant due diligence. I have always felt that by Cessna offering the Thielert engines in a certified model, it validated the Centurion line as an important and viable new source of GA aircraft power. With that in mind, it is troubling to read this, again from AOPA:
"Cessna Aircraft Company has decided not to deliver any Cessna 172TD aircraft powered by the German-built Thielert diesel engine, following the bankruptcy of Thielert Aircraft Engines. None had been delivered, and the type certificate was still pending."
But as we know from our U.S. airlines, bankruptcy is just a way to keep the wolves at bay, and is not necessarily the end of a company, or the end of Thielert. AOPA elaborates, and also drops back into the mix a small but interesting tidbit:
"Meanwhile, sources at TAE in Germany say that the company is still shipping engines and parts, and that no layoffs are anticipated. The bankruptcy will undoubtedly change the landscape of the general aviation diesel-engine movement. Diamond Aircraft is expected to announce production of its own turbodiesel engine at next month’s ILA convention in Berlin, and it’s expected that Lycoming will develop its own general aviation turbodiesel in the near future."
That last sentence woke me right up the minute I read it...a Lycoming GA turbodiesel? Yes, it appears that way back in 1998, Lycoming and Detroit Diesel toyed with the idea, but a certified engine never came of the experiment. I scoured the Internets today and found this from a bNet article dated 1998:
"An aero-diesel engine development program has been announced by Textron Lycoming, Williamsport, Pa., and Detroit Diesel Corp., Detroit, Mich. The two companies will share responsibility for the design, development, certification and manufacture of aero-diesel-engines, should performance, reliability and market targets be met. The new program will study the applicability of a 200 hp, turbocharged engine for general aviation applications. A prototype engine has been placed in a Lycoming test cell for evaluation."
Any other information on that project [a photo of a Lycoming "heavy fuels" engine from Oshkosh can be found here, scroll down] is AWOL from the web, but as a very satisfied Lycoming owner, I'd promise to be overjoyed by the announcement of such an engine.

And with Oshkosh – and with it the official GA announcement season – just a couple of months away now, maybe Lycoming will be smart and jump into the diesel aircraft engine market as a front runner. If there ever was a time to push a turbodiesel GA engine to market, now is that time. The competition is on the ropes, and buyers keep reading about the "greening" of aviation by the elimination of lead in our fuel. If Lycoming were to certify their series of heavy fuel engines, I cannot imagine a world where they would not sell like crazy.

Make it burn Jet A and have a 3,000 TBO, and they would have a tough time building them fast enough.

You Might Also Like