Mindbender
On July 14th, 1986, loose bolts on the wheel assemblies caused the wheels on the final car to become disengaged during a run with a full load of riders.  The train stalled at the top of the last loop, then slid backward.  Three people were killed.  It was one of the worst mechanical failures of a roller coaster in history.

The accident was caused by multiple factors.  Translation problems were found in the change from German to English in the Schwarzkopf maintenance manuals.  Operators were only doing visual inspections of the trains instead of taking them out of service.  Additionally, the wheel assemblies were faulted for not having enough wheels.  Seven months after the accident, the coaster reopened with redesigned wheel assemblies and over-the-shoulder restraints.  The coaster has had an excellent safety record in the last two decades.

©2009 Joel A. Rogers.