In the official synopsis of the Apollo 1 fire, no specific initiation source could be determined. But there's an intriguing idea suggested by the account of the fire in
In the Shadow of the Moon, pages 148-149 of the hardcover edition:
Although it cannot be substantiated, strong circumstantial evidence suggests that Grissom tried to tackle the communication problems by locating and changing a cobra cable inside the spacecraft. This cable was a sheathed, multiwire communication cable that connected each astronaut to the instrument panel, which the crew member could only unplug by turning a ring backward and then pulling on it with substantial force. In actions later verified by NASA's investigation, Grissom unbuckled his seat harness and disconnected his cobra cable. Reliable expert opinion says he then eased himself down into the lower equipment bay, beneath the feed of White and Chaffee, to replace the cable with another. At this time, a slight increase in White's pulse and respiratory rate was recorded, while an electrocardiogram indicated that he was performing some kind of muscular activity that lasted several seconds. Exterior TV cameras also monitored White removing his glove.
The reason for this and his increased muscular activity has never been explained, although he may have been helping Grissom remove and replace the cable. Later hearings would state that the cobra cable was definitely disconnected, and this could not have happened accidentally. White put his glove back on shortly afterward.
I've never seen anyone suggest this, but I wonder if in his movements Grissom may have kicked or stepped on an already damaged electrical cable bundle carrying power and caused the arc that ignited the fire. We know from telemetry that there was a spike in DC power consumption shortly before the fire started, strongly suggesting a short in power wiring. Obviously this is hardly something Grissom can be blamed for, but it might help explain why the fire started at that particular moment. Any thoughts?
