Originally Posted by FBinNY

This is absolutely the key to the matter.

If the case failed to protect the bike because it was crushed, then it's a question of hether it was strong enough to survive the normal stresses of transit. For example they're not designed to survive run over by a tank.

OTOH if the case is intact, then the only way the frame inside could be damaged, would be because contents shifted within due to high g-forces. They'd have to be very high to crack a frame. If the case survived those kinds of forces, then it's stronger than I imagine is possible, but certainly did it's job and can't be blamed.

To say the case failed to protect the bike, and the damage was not caused by either contents shifting because of poor packing, or rough handling by the airline, you'd have to have a damaged case, and show that it wasn't strong enough to survive normal transit stress. Good luck.