You mean when a bird goes down the intake BOAC?!
Or the fuel calcs are wrong (or the wrong fuel gauge fitted!) and plane runs out of fuel?!
Or the water sed checks aren't done correctly and the donk flames out cos it's trying to burn water?!
Can't be anything to do with ash 'cos us engineer's can't find any damage from VA!
Somebody mentioned sand blasting on a Ruinair flight; Atmospheric sand, grit, pollen, small parachutists, what-have-you, is constantly eroding surfaces long before Erecckkkllannnoorrookkkfffic exploded. If you pilot chaps have a close look at your pitot probes and leading edges you'll see they're all eroded to some extent.