Although the contractors had shipped excellent spacecrafts, preparations at Kennedy did not go quickly from the assembly building to the launch pad. Testing was delayed several days in order to stay out of the way of Apollo 9 pre-flight activities. Also during maintenance to the Launch Control Center, the electrical power was switched off to replace a valve. The Apollo 10 launch vehicle’s pneumatic controls sensed the power outage, opened some valves and dumped 20,000 liters of fuel on the launch pad.