The panel had been charged with inspecting spacecraft 012 for structural failures in the January 27 fire and analyzing them from the standpoint of local pressure, temperature levels, direction of gas flow, etc.
The panel inspected the spacecraft structures while they were still at Launch Complex 34 and continued through removal of the CM heatshield. Structural damage reports were made coinciding with spacecraft disassembly phases. As major subsystems were removed from the spacecraft they were visually inspected. Buckles, fractures, cracks, melted areas, localized arcing or pitting in metal components, and obvious direct wire shorts were noted and documented.
Panel findings and determinations included:
Spacecraft data during the Plugs-Out Test gave indications from which a spacecraft pressure history could be estimated.
- The CM cabin structure had ruptured at 6:31:19.4 (±0.1) p.m. EST January 27 at an estimated minimum cabin pressure of 20 newtons per sq cm (29 psia).
- The CM cabin structure had sustained cabin pressure in excess of its designed ultimate pressure of 8.9 newtons-per-sq-cm (12.9-psi) differential (19 newtons per sq cm; 27.6 psia). Cabin pressure at rupture probably reached 20 to 26 newtons per sq cm (29 to 37.7 psia).
- The estimated average gas temperature at rupture exceeded 644 kelvins (700 degrees F).
The CM cabin ruptured in the aft bulkhead adjacent to its juncture with the aft sidewall.
The failure occurred because of excessive meridional tensile stress in the inner face sheet at the junction of the weld land to the thinner face sheet. The fracture originated on the right-hand side of the command module.
The CM cabin structure was penetrated in the aft bulkhead beneath the environmental control unit and the aft sidewall.
- The loss of structural integrity at these penetrations occurred after the primary rupture.
- Failure of the water glycol and oxygen lines near the environmental control unit resulted in local burning and melting of the adjacent structure.
The aft heatshield stainless-steel face sheets were melted and eroded.
The temperature of the flame and gas exiting from the fracture origin exceeded 1640 K (2500 degrees F).