(January 1986) Solid-fueled booster motor leaked combustion gases due to failure of a pressure seal (i.e., O-ring), leading to explosion of liquid fuel tanks and seven fatalities. O-ring had design problems that went unattended. Launch constraints were waived at the expense of flight safety. Safety margins were assumed based on previous successes.
References
- Description from sci.engr.* FAQ on Failures.
- First image from The Challenger Shuttle Disaster.
- Second and third images from The Challenger Disaster: Something to Remember by Joseph Sigg and Rob Howell.
- Fourth image from The Challenger Disaster: What Next?.