MNT.2:4.1 - Turn a task family into a usable policy

Use an adequate existing task and trigger directly. When they are unsettled, construct candidate rules at the resolution needed for the decision. Specify what observation, age, usage or opportunity starts the response, when that information becomes available, what action follows and what functioning is expected afterwards. A condition-based candidate includes its observation schedule and response; a scheduled replacement includes what happens if failure occurs first.

Apply each candidate to the same supported failure and operating account. Follow the relevant histories from functioning through degradation, discovery and response to the resulting state. Include a failure before the planned task and the condition after imperfect repair where those branches matter. Use MNT.3’s failure account and MNT.4’s condition account; obtain an applicable equipment-specific model when projection needs further transition or task-effect evidence. If a consequence needed for the comparison cannot be supported, return that missing contribution rather than assign the desired effect to the task.

Derive the consequences of those histories over a common horizon. Count functioning obtained, losses before detection or restoration, repeated task demand and support constraints. Weight possible histories only where the probability basis supports it; otherwise compare the supported bounds or scenarios. Keep binding requirements and unacceptable consequences visible when comparing burden. Use FPF C.11 with the resulting alternatives and comparison basis to select a policy, retain several alternatives or return the unsettled choice.

For a condition-based candidate, place detection and response on one time basis. Let W be a supported lower bound on the warning from the proposed detectable condition to unacceptable functioning under the intended duty. Let I bound the wait to the next observation and L bound the elapsed time for subsequent interpretation, support, access and intervention, including the selected uncertainty allowance. Where that bounded timing model applies, test I + L <= W. Derive elapsed L from actual sequencing and available overlap through MNT.5 and MNT.7. Shorter sampling, an earlier detectable trigger or prepared support are different candidate changes; each needs its own measurement or feasibility basis. A timing fit still needs adequate detection and an effective response.

For a hidden protective function, relate the test interval to the period during which the failed function could remain undiscovered and the consequences of a demand during that period. The test’s coverage, any exposure it creates and the relevant failure-and-demand account determine whether the interval is acceptable. Continuing normal production supplies no observation of that protective function.