An interesting thread in that it shows a significant number of been there, done that [and got away with it].
A little research shows that the airframe mentioned in the media puts this 135 as a 2002 built Bundespolizei EC135T2 D-HVBM. Contrasted with the fine the whole aircraft is probably not worth much more than a million Euros as a going concern now [but it is the repair costs that they are being saddled with].
The crew were from the Fuldatal Bundespolizei base north of Kassel and the scene of the night time error was Stendal – Borstel airfield north of Stendal in Saxony-Anhalt. The airfield is around 300km [185 miles] from the Fuldatal base. I guess it is going to be a daytime open civil airfield location so the real reason for the million Euros is in the detail we may never know .... the who and how of how access to the wrong fuel was gained? They are the Federal police so they may simply have had a key [really?].
While that detail may never be known, mention has been made of other engines being fuel tolerant but does anyone have access to technical documents specific to the EC135T2 and the Turbomeca Arrius 2B2? The damage was over two sorties so probably no more that 6 hours.
If the turbines were so hot surely that would trigger a high exhaust or engine core reading or caution light to the pilots?
There may be lessons to be learned in the wider audience.