File:CryoMalfunctionsProcedures - Apollo13 CortrightReport pg A-162.png

English: This image shows the salient portion of the official NASA procedure for dealing with a high pressure indication on the cryogenic oxygen tank. It prompts for action to reduce the pressure, to include:

- Turning the four tank heaters and fans off (switch position to center)
- Pulling the two heater circuit breakers (cb) to open to remove the energy source
- Perform a 2-minute purge on all three Fuel Cells (FC), or directly opening the O2 valve (counter-clockwise)

The following is the description presented in Appendix A, page A-162 of the Cortright Report:

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5.0 FUEL CELL/CRYOGENIC SUBSYSTEM MALFUNCTION PROCEDURES

The procedures describe the proper order and nature of emergency steps the crew must perform to determine the source of a fuel cell or cryogenic storage system problem/malfunction. A Caution and Warning alarm and light or abnormal instrumentation indication is evaluated by a malfunction procedure logic diagram. The logic diagrams enable the crew to determine the source of the problem and corrective actions, if required. Fuel cell shutdown and bus short isolation (not related to Caution and Warning) procedures are also presented as part of the malfunction procedures.

The procedures are primarily used as a guide for the flight crew to locate a problem and are presented for the flight monitor as a guide to the crew actions.

The source of the data was CSM 108 (Apollo 12) Flight Malfunction Procedures.

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