Trouble began on the sixth day of the flight, November 17. The capsule developed an atmospheric leak, the pressure first dropping from 760 to 380 mm of Mercury. With the drop in cabin pressure all the animal test subjects died. It would have killed any Cosmonaut not wearing a spacesuit.
Command Service Module-101 started through the manufacturing cycle early in 1966. By July, it had been formed, wired, fitted with subsystems, and made ready for testing. After the Apollo 1 fire in January 1967, changes had to be made, mainly in the wiring, hatch areas, and the forward egress tunnel. It was December before the spacecraft came back into testing. CSM-101 passed through a three-phase customer acceptance review; during the third session, held in Downey on May 7th 1968, no items showed up that might be a “constraint to launch.” North American cleared up what few deficiencies there were (13) and shipped the craft to Kennedy on May 30th 1967…
Had it not been for the fact that Eisele damaged his shoulder during a zero-G training flight aboard a KC-135 aircraft just before Christmas 1965, he might have been in the senior pilot’s seat aboard Apollo 1, instead of Ed White.
The first attempt for a Zond 4 follow-up launched on April 22. It failed when the Launch Escape System sent an erroneous abort command at T+260 seconds and shut down the Proton booster’s second stage. The escape rocket fired and pulled the descent module to safety.