Preventive maintenance and calibration planning process map

What is in this map

12 steps across 5 swimlanes and 5 phases, with 2 decision points.

Swimlanes (who does the work)

Account Management, Calibration Planning, ServiceDesk, Field Service and QA & Documentation

Phases (left to right)

Register & Planning, Interval Determination, Scheduling & Execution, Analysis & Interval Review and Records

Why map this process

Starting from the customer's instrument register rather than a fixed list is what keeps a multi-year service agreement honest: additions, removals and location changes since the last cycle are reconciled at row 1, before criticality is reassessed, so an instrument the customer decommissioned last year does not keep consuming a maintenance slot, and one they added does not go unplanned.

The interval this map determines at row 3 is explicitly framed as a baseline to be tested against real results, not a number set once and left alone — that framing is what justifies the drift-analysis step later in the chart. A service agreement that never revisits its own intervals is really just guessing once and repeating the guess every year regardless of what the calibration history says.

Every step in the map

This is the spreadsheet behind the diagram. The numbers in “Goes to” are row numbers, which is exactly what the editor’s “Line to” column holds — so you can read the flow here and retype any part of it.

The decision points

Every branch in the map, with the label on each outgoing line. These are the questions the process has to be able to answer.

• 6. Result within **tolerance** at this visit?

  Owned by Field Service · Scheduling & Execution

  • Yes → step 8
  • No → step 7

• 9. Adjust interval **necessary?**

  Owned by Calibration Planning · Analysis & Interval Review

  • Yes → step 10
  • No → step 11

Notes on specific steps

These notes travel with the map. In the editor they live in the Notes column and appear when you open a box.

1. Review customer instrument register

The customer's full inventory of instruments under the service agreement. Additions, removals and location changes since the last cycle are reconciled here before criticality is reassessed.

3. Determine *calibration/service interval* per instrument

The starting interval the service agreement is sold against. It is deliberately treated as a baseline to be tested against real results later in the cycle, not a fixed figure set once and left alone.

5. Perform preventive maintenance and calibration check

Runs the as-found/as-left steps in the Instrument Calibration & Documentation SOP against the interval scheduled here; this chart does not repeat those steps, only what triggers and follows them.

7. Flag instrument and hand off to Out-of-Tolerance Calibration SOP

The customer notification, impact assessment and corrective action live in the Out-of-Tolerance Calibration SOP. The result is still carried into this instrument's history so the drift trend reflects it.

8. Analyze *drift trends* across calibration history

Compares as-found readings across this instrument's full calibration history, not just the latest visit. A single in-tolerance result can mask an instrument that is trending toward failure.

10. Revise interval: tighten for drift, loosen where results hold

This is the service agreement's real value to the customer: an instrument that keeps drifting gets a shorter interval, and one with a clean history over several cycles gets a longer one, both on evidence instead of a fixed calendar.

Making it yours

The drift-trend analysis at row 8 deliberately compares an instrument's full calibration history, not just the latest visit's result, before the interval-adjustment decision at row 9. When adapting this map for your own fleet, resist collapsing those into one step: a single in-tolerance result can mask an instrument trending toward failure, which is exactly what the note on that row calls out, and only the historical comparison catches it.

What to watch out for

• Do not let an out-of-tolerance result at a routine visit (row 6, 'No') dead-end this chart. It hands off to the Out-of-Tolerance Calibration SOP for the notification and corrective-action work, but the result is still carried into the instrument's drift history here — losing that carry-over is how an instrument's trend line goes missing right when it matters most.
• Interval revision (row 10) has to run in both directions. This map explicitly tightens the interval for an instrument that is drifting and loosens it for one with a clean history over several cycles — a planning process that only ever tightens intervals is not using the evidence it collects, and a customer paying for shorter intervals that never loosen has a legitimate complaint.
• Do not skip criticality reassessment because it was done last cycle. Row 2 reassesses it every cycle against the reconciled register from row 1, because an instrument's role in the customer's process — and therefore how much a missed interval would cost — can change independently of anything about the instrument itself.

Frequently asked questions