OptimalAvailability Studio™ Wiki / RCM to JA1011
Method
Reliability-centred maintenance
RCM decides what must be done so an asset keeps doing what its users need, in its actual operating context. It is not a maintenance task list, it is the logic that produces one, and SAE JA1011 sets the minimum criteria a process must meet to earn the name.
What RCM is
Reliability-centred maintenance is a structured process for determining the maintenance requirements of a physical asset in its operating context. SAE JA1011 (1999) defines the seven questions any process must answer to be called RCM; SAE JA1012 (2002) is the guide that amplifies it. The best-known development is RCM II, from John Moubray. The output is a task for every failure mode that is worth managing, and a deliberate decision to run others to failure.
The seven questions
To JA1011, RCM answers these in order, for the asset in its context:
| 1. Functions | What the asset must do, and to what performance standard, in this operating context. |
|---|---|
| 2. Functional failures | The ways it can fail to deliver that standard. |
| 3. Failure modes | What can cause each functional failure, at enough detail to manage it. |
| 4. Failure effects | What happens when each failure mode occurs: evidence, damage, downtime. |
| 5. Failure consequences | How and how much each failure matters: safety, environment, operations, cost. |
| 6. Proactive tasks | The task and interval that will predict or prevent each failure, where one is worth doing. |
| 7. Default actions | What to do where no proactive task is suitable: failure-finding, redesign or run-to-failure. |
Failure consequences drive the choice
RCM sorts every failure mode by consequence before choosing a task, because the consequence, not the technical interest of the failure, decides what is worth doing:
| Hidden or evident | First, is the failure evident to the operating crew on its own, or hidden until a second failure or a check reveals it. Hidden failures need failure-finding. |
|---|---|
| Safety and environmental | A failure that could hurt someone or breach the environment. If no proactive task reduces the risk to tolerable, redesign is mandatory. |
| Operational | A failure that costs production, throughput or quality, beyond the repair cost. Worth a task when the task costs less than the consequence. |
| Non-operational | A failure whose only cost is the repair. A task is justified only if it is cheaper than the repair it avoids. |
Task selection
Proactive tasks, chosen only when technically feasible and worth doing:
• On-condition (predictive): detect a potential failure and act inside the P-F interval. Preferred where a P-F interval exists.
• Scheduled restoration: overhaul at a fixed age, where a clear wear-out life exists.
• Scheduled discard: replace at a fixed age regardless of condition, same requirement.
Default actions, where no proactive task suits:
• Failure-finding: periodically test a hidden function (for example a protective device).
• Redesign: mandatory for intolerable safety or environmental risk with no effective task.
• Run-to-failure: a legitimate, deliberate choice where the consequence is minor.
On-condition and the P-F interval
An on-condition task is only feasible when the failure gives warning: a detectable potential failure with a P-F interval that is reasonably consistent and long enough to act within. The monitoring interval must be no more than half the P-F interval so an inspection reliably falls inside the window. This is the exact hand-off to OptimalTREND™, which works the predictive domain and lengthens that interval by detecting earlier. The DIPF curve and the interval rule are covered in depth in the OptimalTREND™ wiki.
Where OptimalAvailability Studio™ fits
OptimalAvailability Studio™ runs the RCM analysis as a living model: functions and failure modes drawn from the FMECA, consequences classified, tasks and intervals selected against the JA1011 logic, and the result packaged as a maintenance strategy that feeds the CMMS, the on-condition tasks to OptimalTREND™, and the criticality to OptimalSPARES™.