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Thielert Diesel Reliability: Mixed at Best…

When Diamond pulled the wraps off its proposed DA42 Twin Star at the Berlin Airshow in May 2002, we thought theyd lost touch with reality. A new twin in the current market? And powered by automotive-influenced diesel engines just then at the prototype stage? Surely they were joking.No, they werent. And 350 Twin Stars later, the jokes on us. The Twin Star has been a smash hit, especially in Europe and Australasia, where avgas is $8 a gallon, if you can find it at all. But there's some tarnish on this bright success story. The Thielert Centurion 1.7 engines that power the Twin Star have accumulated what many owners consider to be a poor service history, with numerous premature replacements, cylinder head cracking and at least 22 inflight stoppages that Thielert confirms.

Paul Bertorelli
Verified

Wh

en Diamond pulled the wraps off its proposed DA42 Twin Star at the Berlin Airshow in May 2002, we thought theyd lost touch with reality. A new twin in the current market? And powered by automotive-influenced diesel engines just then at the prototype stage? Surely they were joking.No, they werent. And 350 Twin Stars later, the jokes on us. The Twin Star has been a smash hit, especially in Europe and Australasia, where avgas is $8 a gallon, if you can find it at all. But there’s some tarnish on this bright success story. The Thielert Centurion 1.7 engines that power the Twin Star have accumulated what many owners consider to be a poor service history, with numerous premature replacements, cylinder head cracking and at least 22 inflight stoppages that Thielert confirms.

Customers complain about Thielerts slow support, lack of ready parts supply and Diamond is apparently so irritated with Thielert that it has started its own engine

Thielert Diesel

company to build the better diesel mousetrap. What went wrong here? In a market that appears so receptive to economical new technology engines, how could Thielert have stirred such ire?

To be sure, many of the Thielert diesels problems appear to be routine teething pains anyone in the aviation business would not only understand, but expect. Its unrealistic to imagine that new technology will take the field without significant bumps and setbacks. But the company doing the fielding has to jolly customers along with ready and unquestioning support and generous warranty response that sends the clear message that “were all in this together.” But customers complain that Thielert hasnt done this. “These guys,” one owner of a diesel-powered Cessna 172 told us, “have a lot to learn about customer service.” Customer service issues aside, Thielert is just now introducing the new-and-improved variant of the Centurion, the 2.0, which it says will correct the 1.7s deficiencies and offer an extended TBR to 2400 hours. Customers are receptive, but many say their patience isn’t infinite.

Our Findings

With growing curiosity, weve been covering the diesel revolution since it declared itself in 2002. With its 135-HP Centurion 1.7 diesel influenced by a Mercedes-Benz

Paul Bertorelli

Paul Bertorelli is Aviation Consumer’s Editor at Large. In addition to his valued contributions to Aviation Consumer, his in-depth video productions on sister publication AVweb cover a wide variety of topics that greatly contribute to safety, operation and aircraft ownership. When Paul isn’t writing or filming, he’s out flying his J3 Cub.