When Diamond was hard into its certification of the DA42 Twin Star in 2005, it knew it was taking a big chance on the untried Thielert 1.7 diesel engines. But it also hedged its bets by running a near parallel certification effort of the same airplane fitted with Lycoming’s angle-valve IO-360, a well proven powerplant. It back-burnered the Lycoming project once it appeared that the diesel engines were both preferred and were gaining ground in the market.

It now appears as though the Lycoming hedge is paying off, by necessity. As is well known by now, the Thielert diesels turned out to have a spotty service record at best, a disastrous…