Encyclopedia Astronautica
1967.03.19 - Apollo 204 Review Board cited a number of findings on flammable materials in spacecraft 012


The Materials Work Panel (Panel 8, also referred to as Materials Review' Panel) in its final report accepted by the Apollo 204 Review Board cited a number of findings on flammable materials in spacecraft 012.

The panel's task had included the following, from its detailed work statement:

- "Assemble, summarize, compare and interpret requirements and data describing the flammability of nonmetallic materials exposed to the crew bay environment of the spacecraft and in related applications.
- "Specify and authorize performance of tests and/or analyses to furnish additional information as to flammability characteristics of these materials alone, and in combination with fluids known or postulated to have been in the spacecraft 012 cabin.
- "Panel No. 8, in support of Panel No. 5 (Origin and Propagation of Fire) shall interpret and implement the requirements for analyses of debris removed from the spacecraft."

Panel 8 classified its findings in six categories: Materials Configuration; Routine Materials Test; Fire Initiation Special Investigation; Fire Propagation Special Investigation; Materials Installation Criteria and Controls; and Technical Data and Information Availability. The findings and determinations included:

Finding

Complete documentation identifying potentially combustible nonmetallic materials in spacecraft 012 was not available in a single readily usable format. A total of 2,528 different potentially combustible nonmetallic materials that were probably used on spacecraft 012 was found by a review of available documentation.

Determination

The program for identifying and documenting nonmetallic materials used in the spacecraft, including their weights and surface areas, was not adequate.

Finding

Raschel Knit, Velcro, Trilock, and polyurethane foams burn about twice as fast (in the downward direction) in oxygen at a pressure of 11.4 newtons per sq cm (16.5 psia) as at 3.5 newtons per sq cm (5 psia).

Determination

The primary fuels for the fire burned more than twice as fast in the early stages of the spacecraft 012 fire in accident conditions (pressure of 11.4 newtons per sq cm) as in the space flight atmosphere for which they were evaluated (3.5 newtons per sq cm).

Finding

Surface and bulk damage of materials in spacecraft 012 varied from melting and blistering of aluminum alloys, combustion of Velcro, and burning of Teflon wire insulation to slight surface damage and melting of nylon fabrics.

Determination

The fire filled the spacecraft interior. The most intense heat was in the lower left front area around the environmental control unit. Surface temperatures in excess of 800 kelvins (1,000 degrees F) were reached in areas such as the front and left side of the spacecraft. Surface temperatures were less than 500 K (400 degrees F) in isolated pockets above the right-hand couch.

Finding

The rate of flame propagation, the rate of pressure increase, the maximum pressures achieved, and the extent of conflagration in 3.5 newtons-per-sq-cm (5-psia) oxygen boilerplate tests was much less severe than observed in the 11.4-newton (16.5-psia) oxygen boilerplate tests. Burning or charring was limited to approximately 29 percent of the nonmetallic materials by oxygen depletion.

Determination

The conflagration that occurred in spacecraft 012 at a pressure of 11.4 newtons per sq cm would be far less severe and slower in a spacecraft operating with an oxygen environment at 3.5 newtons, if additional large quantities of oxygen are not fed into the fire.

Finding

North American Aviation materials selection specification requires that a material pass only a 500 K (400 degrees F) spark-ignition test in oxygen at 10.1 newtons per sq cm (14.7 psia).

Determination

NAA criteria for materials flammability control were inadequate.

Finding

No flammability criteria or control existed covering nonflight items installed in CM 012 for test.

Determination

Lack of control of nonflight material could have contributed to the fire.

Finding

The NASA materials selection criteria required that a material pass a 500 K (400 degrees F) spark-ignition test and a 1.27-an-per-sec combustion rate (measured downward in oxygen at 3.5 newtons per sq cm). Raschel Knit and Velcro (hook) pass this test.

Determination

The NASA criteria for materials flammability were not sufficiently stringent.

Finding

The system for control of nonmetallic materials use at MSC during the design and development of government furnished equipment used in CM 012 depended on identification of noncompliance with criteria by the development engineers.

Determination

The NASA materials control system was permissive to the extent that installation or use of flammable materials were not adequately reviewed by a second party.

Finding

Nonmetallic materials selection criteria used by North American and NASA were not consistent. The NASA criteria, although more stringent, were not contractually imposed on the spacecraft contractor.

Determination

Materials were evaluated and selected for use in CM 012 using different criteria. Application of the NASA criteria to the command module would have reduced the amount of the more flammable materials (Velcro and Uralane foam).

Finding

Alternate materials that are nonflammable or significantly less flammable than those used on spacecraft 012 were available for many applications.

Determination

The amount of combustible material used in command modules can be limited.

Finding

Current information and displays of the potentially flammable materials configuration of spacecraft 012 were not available before the fire.

Determination

Maintenance of data and displays at central locations and test sites for management visibility and control of flammable materials is feasible and useful.

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