This is a ready-to-use decision matrix for the single most argued-over line in an equipment program: is this action routine maintenance, or does it belong in change control. The same judgment made differently by different people, on different shifts, for the same class of action, is one of the most common paths to a qualified state quietly breaking without anyone evaluating it. Replace every <<FILL: ...>> placeholder with your own specifics. A filled specimen follows. This content is general educational reference, not legal or regulatory advice.
Document control header
| Field | Entry |
|---|---|
| Matrix title | Maintenance versus Change Control Boundary Decision |
| Document number | <<FILL: MTX-ID>> |
| Version | <<FILL: version>> |
| Effective date | <<FILL: date>> |
| Owner | <<FILL: role, e.g. Head of Engineering / Validation>> |
| Applies to | <<FILL: sites / equipment classes in scope>> |
1. Purpose
Give maintenance technicians, engineers, and equipment owners a single, consistent test for deciding whether an action on qualified equipment can proceed under a maintenance work order or must be raised in change control, so the same class of action is classified the same way regardless of who makes the call or when.
2. The three-question test
Apply these three questions, in order, to any proposed replacement, adjustment, or repair on qualified equipment. The first “no” answer, or the first “yes” to a critical-function question, ends the test and routes the action to change control.
| # | Question | If the answer changes the routing |
|---|---|---|
| 1 | Is the part or setting being restored to its original, validated specification (a genuine like-for-like replacement, or a repair that returns the equipment to its qualified condition with no change to design, logic, or configuration)? | No: change control |
| 2 | Does the action touch a critical function, control logic, software, firmware, or a parameter inside the qualified operating envelope? | Yes: change control, regardless of the answer to question 1 |
| 3 | Is the replacement part genuinely equivalent in specification, fit, and function, with the equivalence basis documented (same part number, or a proven-equivalent alternate with a written comparison)? | No, or equivalence cannot be demonstrated: change control |
An action that passes all three (restores original specification, touches no critical function, and uses a documented equivalent part) is handled under maintenance, with the equivalence basis recorded on the work order and calibration verified on any affected measuring instrument. Everything else is a change.
3. Scenario matrix
Use this table as a starting reference for common actions, then classify your own site’s recurring scenarios the same way and add them below. No table can cover every case; where a real action does not clearly match a row, escalate under section 5 rather than guessing.
| Scenario | Touches a critical function? | Like-for-like / equivalent? | Classification | Rationale |
|---|---|---|---|---|
| Sensor or probe replaced with the identical part number | Depends on the sensor’s role | Yes | Maintenance if the sensor is not itself a critical control input; change control if it drives a critical alarm, interlock, or control loop | A temperature indicator that only displays is different from the thermocouple that controls a sterilization cycle |
| Gasket, seal, or filter replaced with the identical part number, no design change | No | Yes | Maintenance | Wear item restored to specification, no functional change |
| Controller or PLC replaced with a new model or firmware revision | Yes | No | Change control | Control logic, software, and often the qualified interface all change |
| Software or firmware patched (security or bug fix only, no functional change) | Depends on scope | No, a version change by definition | Change control, scaled to risk | Even a “minor” patch changes the validated baseline; the depth of testing scales to what the patch actually touches |
| Mechanical adjustment (belt tension, door alignment) returning equipment to its original operating condition | No | N/A, adjustment not replacement | Maintenance | Restores original condition, no design or setpoint change |
| Setpoint or alarm limit changed from the qualified value | Yes | N/A | Change control | Directly alters the qualified operating envelope |
| Calibration interval shortened based on observed drift | No | N/A | Maintenance/metrology action, documented at periodic review | Tightens a control, does not change equipment design or function |
| Equipment relocated to a new room or utility connection | Yes | No | Change control | New installation conditions invalidate at least IQ |
| A new product or load pattern added within the already-qualified envelope | Depends | N/A | Maintenance-level notification is not sufficient; assess for PQ/cleaning impact under change control | Use pattern change can exceed what PQ actually challenged |
| Emergency repair performed out of hours to restore basic function | Depends on what was touched | Assessed retrospectively | Emergency change control pathway, assessed as soon as practicable after the repair | Urgency does not remove the requirement to assess qualification impact; it changes the timing of the assessment, not whether one happens |
4. Acceptance criteria
- Every classification decision states which of the three questions drove the outcome, not just the conclusion.
- A “like-for-like” or “equivalent” claim carries a documented basis (part number match, or a written specification comparison), never asserted with no basis.
- Any action touching a critical function, control logic, software, or the qualified envelope is routed to change control regardless of how minor it appears.
- Emergency repairs are assessed for qualification impact as soon as practicable after the repair, not exempted from assessment because they were urgent.
- A record of every maintenance-classified action is captured so periodic review can reconstruct the cumulative picture of what changed, even when no single action required change control on its own.
5. Escalation when the classification is not obvious
| Situation | Route |
|---|---|
| The technician or engineer is unsure whether question 2 applies | Escalate to the equipment SME before proceeding; do not default to maintenance to save time |
| Two people would reasonably classify the same scenario differently | Add the scenario to this matrix once resolved, so the decision is made once and applied consistently afterward |
| A “maintenance” action, on reflection, may have touched a critical function | Raise it in change control retrospectively and assess qualification impact; a late change record is a better outcome than none |
6. References
US 21 CFR 211.63 (equipment design) and 211.68(b) (written procedures for changes to automated, mechanical, and electronic equipment). EU GMP Annex 15 (Qualification and Validation, 2015 revision), requalification assessed on a risk basis following change. EU GMP Chapter 3 (premises and equipment maintenance). ICH Q9(R1), Quality Risk Management, for the risk basis behind the critical-function test.
Confirm the current version and clause numbers of each reference before issue.
7. Revision history
| Version | Date | Author | Summary of change |
|---|---|---|---|
<<FILL: 1.0>> | <<FILL: date>> | <<FILL: author>> | Initial issue. |
8. Approvals
| Role | Name | Signature | Date |
|---|---|---|---|
| Engineering / Maintenance | <<FILL>> | ||
| Validation / Qualification SME | <<FILL>> | ||
| QA | <<FILL>> |
Filled specimen
The following shows the matrix applied to three real actions on the same autoclave (STZ-04) in one quarter, so the same equipment can be seen producing three different outcomes depending on what actually happened. Numbers are illustrative.
Action A: door gasket replaced, identical part number. Question 1: yes, restores original specification. Question 2: no, the gasket is a static seal, not a control input. Question 3: yes, identical part number. Classification: maintenance. Documented on work order WO-2026-1140 with the part number recorded; no change control raised.
Action B: chamber pressure transducer replaced after a periodic review flagged drift toward the tolerance limit. Question 1: yes, a routine replacement of a wearing component with an identical part. Question 2: yes, this transducer feeds the cycle’s control logic and its readings gate cycle acceptance. Because question 2 answers yes, the classification is change control regardless of the like-for-like part. Change record CC-2026-301 raised; scope assessed as calibration re-verification plus an OQ check of the pressure alarm function, per the paired Form: Requalification Impact Assessment and Scope Determination.
Action C: door alignment adjusted after a technician noticed slightly uneven closure force. Question 1: yes, this restores the door to its original qualified alignment; no part is replaced and no design changes. Question 2: no, alignment within specification does not touch the sterilization control logic. Classification: maintenance. Documented on work order WO-2026-1188.
The value of running all three through the same test on the same asset is visible here: a nearly identical action (replacing a small component with the same part number) produces opposite classifications for the gasket and the transducer, because question 2, not question 1 or 3, is what actually decides it.
Common inspection findings this matrix prevents
- Material changes repeatedly logged as like-for-like maintenance to avoid the requalification that change control would trigger.
- The same class of action classified differently by different people with no documented rule to reconcile the difference.
- A critical-function replacement handled as routine maintenance because the replacement part happened to be the identical part number, with question 2 never asked.
- Emergency repairs treated as permanently exempt from qualification-impact assessment rather than assessed retrospectively.
- No record of maintenance-classified actions for periodic review to reconstruct, so a string of individually defensible swaps is never evaluated in aggregate.
How to adapt this matrix
- Set the document number, owner, and effective date in the header.
- Replace the scenario matrix in section 3 with your own equipment types and the recurring actions your maintenance and engineering teams actually perform; keep the reasoning column, not just the classification.
- Point the escalation route in section 5 to your real SME and change control functions.
- Reference this matrix from your requalification/periodic review procedure and your change control procedure, so both point to the same boundary rule rather than each defining its own.
- Confirm every regulation in section 6 against the current published version before issue.