I know diesel isn't avtur and unleaded isn't avgas but I believe they're similar enough for this story to be possibly relevant...
The old man filled our old petrol Peugeot 504 with diesel by mistake at a servo on the Hume Highway. He headed off down the highway as normal and several kilometres later, with no warning, it suddenly belched a large cloud of smoke and the engine stopped dead. There was no mixing of those fuels I can tell you.
To answer the replies below... the engine ran fine after the lines had been blown out and fuel introduced. There would not have been pre-detonation or anything like it. The diesel simply did not combust, however by coming into contact with the fuel in the lines a small amount of mixing occured in the fuel line, and the hot engine interior would have created some smoke from the diesel, enough to create a few seconds worth of clouds of white smoke from the exhaust. Pre-detonation occurs when you introduce a lighter grade of fuel into a diesel, as in petrol into a diesel, but not the other way around.
Last edited by nojwod; 13th Aug 2010 at 12:59.