Example 1 1-3
Compute the availability and the unavailability for both the alarm and the shutdown systems of Example 11-2. Assume that a maintenance inspection occurs once every month and that the repair time is negligible. Solution Both systems demonstrate unrevealed failures. For the alarm system the failure rate is p = 0.18 faultslyr. The inspection period is 1/12 = 0.083 yr. The unavailability is computed using Equation 11-25: