MNT.13:4 - Solution

Bound the population, service question and horizon. Identify the programme decision at stake: retain a policy, change a task, improve spare readiness, resolve a backlog or compare performance. An equipment-family name alone does not establish that units have comparable duty or failure behaviour.

Recover the event and exposure basis under MNT.3 and MNT.12. Distinguish failures, inspections, preventive removals and incomplete observation. Compare units at compatible configuration, operating conditions and consequence where those differences can change the answer. Retain a stratified account when aggregation would conceal the difference.

Relate the observations to possible programme causes and actions. Repeated waiting for an applicable spare can justify a support decision without proving that the preventive policy is ineffective. A changed reporting rule can increase counted failures without worsening the machine. Use the failure and operating evidence to distinguish these interpretations.

Compare credible programme alternatives. Retain a sound existing arrangement, change one policy family, improve support, alter coordination or return a design question as appropriate. Include the total obtaining and continuing burden of the change, its effect on service and any protected trade-offs. A local cost reduction that increases shared downtime is not an unqualified programme gain.

When a deliberate improvement is selected, use E.23’s loop at this subject: name the programme arrangement and the maintenance contribution sought, choose the evaluation that will judge it, perform the selected change only when authorized, and compare the changed arrangement through the same relevant measures. Selection, implementation and observed effect remain different facts.

Choose further fleet inquiry only when its attainable result can change the decision enough to warrant its design, access, measurement, interpretation and displaced work. If current evidence already supports retaining the policy or fixing a known support deficiency, return that answer now. Sparse or incomparable data withholds the stronger causal claim, not every programme decision.

Return the decision with the population and evidence limits that affect its use. Identify the recurrence, changed duty, support failure or new professional result that would reopen it. A long-term learning question can remain open while today’s programme answer is complete.