RMP.3:5.1 - Pump-P4: from a mechanism question to an executable comparison
The brief asks whether the accelerated condition preserves the field seal-degradation mechanism within a specified material/fluid envelope. The selected design compares accelerated and field-representative conditions. Assume the domain owner supplies a valid mechanism marker, qualified measurement procedure, safe conditions and an adequate specimen plan.
The team adds these entries to its existing protocol:
| Protocol choice | Question-relative reason and required record |
|---|---|
| Give each seal a specimen ID and retain its material batch and assigned condition. | The comparison concerns degradation under the two conditions; material and allocation must remain recoverable. |
| Measure the supplied mechanism marker at the design’s specified exposure points with the qualified procedure. | A difference must bear on mechanism, not merely on total visible wear. Retain the procedure version, calibration basis, time and uncertainty. |
| Treat three readings from one seal as repeated observations of that seal. | Repetition can characterize measurement variation; it does not triple the independent specimen count in the supplied comparison. |
| Preserve missing observations and departures before preparing the comparison data. | A critic needs to distinguish material behaviour from allocation, handling and selection effects. |
This is an operationalization of the selected design because each choice preserves the mechanism question and names the material needed to challenge it. The team does not obtain permission or a maintenance decision merely by completing the protocol.
Now change one premise: the measurement owner reports that the marker cannot distinguish thermal degradation from the competing field mechanism under these conditions. The appropriate result is an RMP.2 return carrying that report and the lost discrimination. Substituting a more convenient wear score would require a justified new evidence relation. The brief and unaffected specimen information can remain useful.
On the valid-marker branch, specimen P4-07 is later damaged in handling before an observation. The protocol’s planned missingness treatment tells the team what intention to consult; RMP.4 records what actually happened and what was decided. Whether the remaining data support an inference is a later analytical question.