As the title suggests, when a Rock Crusher Multiblock is destroyed (e.g. with a pickaxe), only the output inventory slots are dropped into the world, the contents of the input slots are simply destroyed.
I have checked all the other multiblocks and they all seem drop their inventories just fine.

Tested with Railcraft 9.4.0.0 on Forge 7.10.85.1270

Yes I have. This issue only occurs when enough blocks are broken to make the Rock Crusher eject its output inventory. As long as you only take out a few blocks both inventories are retained.

Oh, have you tried to build it again at the same place? Maybe you will find those things in its inventory.

So it'll be the bug of all the multiblock structures not only Rock Crusher.

I think this is a similar issue to the steam boiler bug I squashed a while back. It had to do with slave/master inventory issues when broken.

I don't really see any possible way that it could only drop half the inventory.

Tested and verified. Attempting to trace.

Appears to be an issue with sided handling of the inventory.