scope:

Abstract:

During lot acceptance test of ten Mars Observer pyro valves, none failed. Yet, post-test examination showed that each of these valves had sustained erosion (burning) of about 50 percent of their threads. A study showed that some firings result in the pyro being ejected from the valve body at speeds of approximately 200 m/s, which could damage critical hardware.

Users of NSIs should be alerted to this possibility. Acceptance or qualification testing should include post-test examination of inferred margin or incipient failure modes. The use of titanium in pyrotechnic applications should be avoided.