34. Lesson: Redundancy Design
When designing redundancies into systems, consider the use of nonidentical approaches for backup, alternate, and redundant items.
A fundamental design deficiency can exist in both the prime and backup system if they are identical. For example, the rate gyros in the Skylab attitude control system were completely redundant systems, i.e., six rate gyros were available, two in each axis. However, the heater elements on all gyros were identical and had the same failure mode. Thus, there was no true redundancy and a separate set of gyros had to be sent up on Skylab 4 for an in-flight replacement.
These lessons learned are from SKYLAB LESSONS LEARNED AS APPLICABLE TO A LARGE SPACE STATION, A dissertation submitted to the faculty of The School of Engineering and Architecture Of the Catholic University of America For the Degree Doctor of Engineering by William C. Schneider, Washington, D.C., 1976.
Home - NASA Office of Logic Design
Last Revised: February 03, 2010
Digital Engineering Institute
Web Grunt: Richard Katz