Now that Thielert Motoren GmbH goes through severe financial troubles, the natural questions are the future of its line of aero diesels, and how it affects the whole aero diesel industry as a whole.
Where did Frank Thielert go wrong?
Our impression from messages received from the fleet managers, most of them stuck with Diamond DA40 and 42, is: If Thielert did deliver on customer service and spare parts, and if rigorous procedures were applied for preventive maintenance, the Thielert engine would be costly to maintain but would do the job. The users would impatiently wait for a new generation of similar engines where the bugs would have been weeded out.
A frequent opinion in the US says: The in-line water-cooled geared engine derived from an automobile engine block was a flawed concept in the first place. Diamond Air does not think so: the Austro line it is developing in-house with Mercedes contribution looks very much like an improved Thielert, taking into account what Diamond learned, which is a lot.
If Diamond is on the right track, it is a case for them acquiring Thielert: the Austro line could be manufactured by the Thielert facility. It would take retooling. If Cessna joins in with a long term contract for their needs, it would reduce delays in bringing the 172 and 206 diesel to market.
For the same reason, there is an alternative case for Textron, who owns Cessna and Lycoming, to consider acquiring Thielert itself in context of a long term agreement with Diamond.
What about Teledyne Continental? Not impossible. But we perceive Continental as less in need to jump on the diesel bandwagon now. They may be the one who decide to wait and develop their own line.
Will the whole saga delay aero diesel progress? Certainly. But SMA, Wilksch and DeltaHawk are making progress, with different designs, aiming at different market segments; and meanwhile the world outside the US badly needs aero diesels now: This is also a message we read regularly from Africa, Europe, the Middle East and Latin America: 'Our problem is we are stuck with our fleet: Avgas is no more available.'
Of course as always in aviation, all progresses are very slow. And the drama at Thielert may well be that the engine simply was certified too soon.
The dramatic component in the Thielert saga is how its management handled the stock market. It imposes extremely dangerous short term conditions for a small firm handling an engineering-intensive component for which customer service is so extremely decentralized.
One thing is for sure: 30 years from now, there will be many, many aero diesels between 100 and 500 HP flying in the world. To get there, everyone fasten your seatbelts.