|astronautix.com||Apollo S-IVB stage for Saturn launch vehicle 503 exploded|
The Saturn 503 S-IVB stage exploded and was destroyed at the Douglas Sacramento, Calif., Test Facility at 4:25 p.m. PST during a countdown. The exercise had progressed to 10 seconds before simulated launch (about 8 minutes before S-IVB ignition) when the explosion occurred.
Earlier that day the countdown had progressed to about 6 minutes past simulated launch when a problem with the GSE computer tape carrier head required a hold and a recycling in the countdown. No one was injured.
A Douglas Aircraft Company investigating team under Jack Bromberg started operations the next morning, and an MSFC-appointed investigating board chaired by Kurt Debus, KSC, began operating three days after the accident. References: 16 .