Engine shock-loading

[Deeday]

What sort of damage does actually derive from engine shock-loading, anybody knows? I mean, what component does actually take the shock: crankshaft, bearings, any gearbox (e.g. Rotax engines)?
And say that while I'm taxiing on bumpy grass, the propeller strikes the ground (without the engine stopping): does that make the engine not airworthy until inspected/repaired?

Thanks for sharing your knowledge!

Deeday