I vaguely remember reading a report about a US Marine Corps C-130 which was overloaded accidentally; part of the load was a large cross-country capable fork-lift; apparently the guy working out the loading read the safe working load of the vehicle (painted on the forks) as the weight of the vehicle (displayed somewhere not as easily seen). Can't remember what happened but someone else picked it up and it didn't even get as far as starting engines.
US Navy Aviation Safety website may be able to give you some other examples; back in a min with a link.
http://www.safetycenter.navy.mil/med...ch/default.htm