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More Details for 1967-03-30

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The Apollo 204 Review Board accepted the final report of its Design Review Panel (No.9).

The Panel's duty had been to conduct Critical Design Reviews of systems or subsystems that might be potential ignition sources within the Apollo command module cockpit or that might provide a combustible condition in either normal or failed conditions. The panel was also to consider areas such as the glycol plumbing configuration; electrical wiring and its protection, physical and electrical; and such potential ignition sources as motors, relays, and corona discharge. Other areas would include egress augmentation and the basic cabin atmosphere concept (one-gas versus two-gas).

The contemplated spacecraft configuration for the next scheduled manned flight (spacecraft 101, Block II) was significantly different from that of spacecraft 012 (Block I), in which the January 27 fire had occurred. Therefore, both configurations were to be reviewed - the Block I configuration as an aid in determining possible sources for the fire, the Block II to evaluate the system design characteristics and potential design change requirements to prevent recurrence of fire.

The panel's final report to the Review Board contained findings on ignition and flammability, cabin atmosphere, review of egress process, and review of the flight and ground voice communications. Among them were:

Finding

Flammable, nonmetallic materials were used throughout the spacecraft. In the Block I and Block II spacecraft design, combustible materials were contiguous to potential ignition sources.

Determination

In the Block I and Block II spacecraft design, combustible materials were exposed in sufficient quantities to constitute a fire hazard.

Finding

The spacesuit contained power wiring to electronic circuits. The astronauts could be electrically insulated.

Determination

Both the power wiring and potential for static discharge constituted possible ignition sources in the presence of combustible materials. The wiring in the suit could fail from working or bending.

Finding

Residues of RS89 (inhibited ethylene glycol/water solution) after drying were both corrosive and combustible. RS89 was corrosive to wire bundles because of its inhibitor.

Determination

Because of the corrosive and combustible properties of the residues, RS89 coolant could, in itself, provide all of the elements of a fire hazard if it leaked onto electrical equipment.

Finding

Water/glycol was combustible, although not easily ignited.

Determination

Leakage of water/glycol in the cabin would increase risk of fire.

Finding

Deficiencies in design, manufacture, and quality control were found in the postfire inspection of the wire installation.

Determination

There was an undesirable risk exposure, which should have been prevented by both the contractor and the government.

Finding

The spacecraft atmosphere control system design was based on providing a pure oxygen environment.

Determination

The technology was so complex that, to provide diluent gases, duplication of the atmosphere control components as well as addition of a mechanism for oxygen partial-pressure control would be required. These additions would introduce additional crew-safety failure modes into the flight systems.

Finding

Sixty seconds were required for unaided crew egress from the CM. The hatch could not be opened with positive cabin pressure above approximately 0.17 newtons per sq cm (0.25 psi). The vent capacity was insufficient to accommodate the pressure buildup in the Apollo 204 spacecraft.

Determination

Even under optimum conditions emergency crew egress from Apollo 204 spacecraft could not have been accomplished in sufficient time.

Finding

During the January 27 Apollo 204 test, difficulty was experienced in communicating from ground to spacecraft and among ground stations.

Determination

The ground system design was not compatible with operational requirements.