On figure 5 is shown a chart depicting the organization of the Board. The four Panels-Mission Events, Manufacturing and Test, Design, and Project Management-are shown along with the subpanels and the supporting office structure. The membership and responsibilities of each Panel are set forth in the Report.

While the Board's intensive review activities were underway, the Manned Spacecraft Center Apollo 13 Investigation Team, under James A. McDivitt, Director of the MSC Apollo Spacecraft Program Office, was also conducting its own analysis of the Apollo 13 accident. Coordination between the Investigation Team work and the Apollo 13 Review Board activities was effected through the Manned Space Flight Technical Support official and by maintaining a close and continuing working relationship between the Panel Chairmen and officials of the MSC Investigation Team. In addition, Board members regularly attended daily status meetings of the Manned Spacecraft Center Investigation Team. In general, the Board relied on Manned Spacecraft Center post-mission evaluation activities to provide the factual data base for evaluation, assessment, and analysis efforts. However, the Board, through a regular procedure, also levied specific data collection, reduction, and analysis requirements on MSC. Test support for the Board was provided by MSC, but in addition, the Board established an extensive series of special tests and analyses at other NASA Centers and at contractor facilities. Members of the Board and its Panels also visited contractor facilities to review manufacturing, assembly, and test procedures applicable to Apollo 13 mission equipment.

In this test program, which included nearly 100 separate tests, and which involved several hundred people at its peak, the elements of the inflight accident were reproduced. All indications are that electrically initiated combustion of Teflon insulation in oxygen tank No. 2 in the service module was the cause of the Apollo 13 accident. One series of tests demonstrated electrical ignition of Teflon insulation in supercritical oxygen under zero g and at one g, and provided data on ignition energies and burning rates. Other tests, culminating in a complete flight tank combustion test, demonstrated the most probable tank failure mode. Simulated tank rupture tests in a 2 scale service module verified the pressure levels necessary to eject the panel from the service module. Other special tests and analyses clarified how they might have been generated. I have with me a brief film, highlighting these tests, which I would like to show at the conclusion of my statement.

APOLLO 13 SYSTEMS

Before tracing the analyses which led to the Board's conclusions—and to place them in proper context-I would like to explain the design and functions of the oxygen tank #2 as a part of the Apollo system. Details of the entire Apollo/ Saturn Space Vehicle are set forth in the Report and its Appendices.

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Figure 6 shows the Apollo/Saturn Space Vehicle, with which you are all familiar. Figure 7 shows the service module which, as you know, is designed to provide the main spacecraft propulsion and maneuvering capability during a

mission. It also contains most of the spacecraft consumables (oxygen, water, propellant, and hydrogen) and supplies electrical power. The service module is divided into six sectors or bays surrounding a center section. The oxygen tank, to which I referred, is located in Bay 4 (shown in more detail on figure 8),

NASA-S-70-512-V

ARRANGEMENT OF FUEL CELLS AND CRYOGENIC
SYSTEMS IN BAY 4

along with another oxygen tank, two hydrogen tanks, three fuel cells and interconnecting lines, and measuring and control equipment. The tanks supply oxygen to the environmental control system (ECS) for the astronauts to breathe, and oxygen and hydrogen to the fuel cells. The fuel cells generate the electrical power for the command and service modules during a mission. The next slides (figures 9, 10, and 11) are photographs of Bay 4 of the service module for Apollo 13, showing the major elements and their interconnection. Slide 7 shows the oxygen tank #2 in place.