The clear pictures you can see above (click to enlarge) are from an
internal briefing of the Finnish
Air Force which reports about the damage to some of their jet engines after
flying into the cloud of volcanic ash that moved over european skies in
recent days (the title of the briefing Tuhkatilanne –
tiedotustilaisuus  predictably means "briefing on the ash
situation").

In the upper part of the picture you can see the structure of a jet
engine (a component that you might be familiar with – if you looked at the
engines in a normal scheduled flight – is the fan that you see on the
far left of the diagram). The bottom image contains photos of
damage to different parts of the engine (the red arrows indicate the
precise point on the structure of the engine: the first photo on the
left concerns the fan blades, the others are internal engine parts).

Those who questioned risks of volcanic ash from Eyjafjallajökull
perhaps should take a look at these images.