40 per-cent nitrogen prelaunch atmosphere in Apollo - .
Nation: USA. Related Persons: Faget; Slayton. Program: Apollo. Spacecraft: Apollo CSM; CSM Communications. A Senior Flammability Review Board meeting at MSC reached a number of decisions on the CSM. Attending were Robert R. Gilruth, chairman; George M. Low, Kenneth S. Kleinknecht, Aleck C. Bond, Maxime A. Faget, Donald K. Slayton, Charles A. Berry, and Rodney G. Rose, all of MSC; Samuel C. Phillips, NASA Hq.; William B. Bergen and Dale D. Myers, North American Rockwell; and George Stoner, Boeing (nonvoting observer).
Several previous action assignments were reviewed:
The Board presented a review of test results. In the tests at pressure of 4.3 newtons per square centimeter (6.2 pounds per square inch) in a 95-percent oxygen atmosphere, there were 38 ignitions in boilerplate 1224. Of these,5 produced fires large enough to require further consideration. In tests at 11.2 newtons per sq cm (16.2 psia) in a 60-percent-oxygen and 40-percent nitrogen atmosphere, there were 31 ignitions. Of these, 4 produced fires large enough to require further consideration.
- Component level Flammability Test Program - North American reviewed the results of its material identification and test program, the component test program, and the boilerplate 1,250 tests. These tests had provided the basis for design decisions on selection and application of CM nonmetallic materials.
- Boilerplate 1224 configuration comparison to CSMs 2TV-1 and 101 - North American presented the comparison and the Board decided that the boilerplate configuration was representative of the "worst case" configuration, considering both 2TV-l and 101.
- Internal ignition rationale - ignition rationale for the boilerplate 1224 tests was presented to the Board. Nichrome wire ignitors were used with the ignitor wire embedded in potting. In some locations a Ladicote cover was applied over the potting and ignitor. The Board pointed out that the ignition techniques were not really representative of actual operating conditions and were indeed overly severe.
- Crew communications umbilical - North American was evaluating a fluorel crew communications umbilical as well as fluorel oxygen umbilicals. A Beta sleeve over the oxygen and crew communications umbilicals would also be evaluated for its operational acceptability by the Crew.
The Board concluded that the material changes made in the CM had resulted in a safe configuration in both the tested atmospheres. The Board agreed "that there will always be a degree of risk associated with manned space flight," but the risk of fire "was now substantially less than the basic risks inherent in manned space flight."
Among decisions reached were:
A final decision would be made at the Design Certification Review on March 7.
- the CSM 2TV-1 and 101 coaxial cable configuration would be tested in the 60-percent-oxygen and 40-percent nitrogen atmosphere;
- material improvements and testing would be continued and changes would be phased in, pending the availability of proved materials; and
- action would be taken to be prepared to use a 60-percent-oxygen and 40-percent-nitrogen prelaunch atmosphere in CSM 101.