What "officially recognised standard" actually means
Part-145 requires that all tools, equipment, and test equipment be controlled and calibrated to an officially recognised standard, at a frequency that ensures serviceability and accuracy. The phrase does the heavy lifting in the rule, so it is worth being precise about it.
The AMC clarifies the intent: an officially recognised standard is one published by an official body that is widely recognised as good practice. In practice this points to the manufacturer's recommendations where they exist, and to ISO 10012 — the measurement management standard — for the system that sets and reviews the intervals.
Who sets the interval: OEM first, ISO 10012 otherwise
The calibration interval is not a number pulled from thin air. The correct starting point is the manufacturer's recommendation for the tool or instrument. Where no OEM recommendation exists, ISO 10012's measurement-management approach is the recognised fallback for deciding how often an item must be re-calibrated.
The interval decision is recorded policy, not a spreadsheet guess. And the same discipline applies to the traceability question: once an item is calibrated, the record must be traceable to the standard that was actually used.
The labs behind it: ISO/IEC 17025 and ILAC-MRA traceability
Calibration that supports the Part-145 obligation is normally performed by laboratories accredited to ISO/IEC 17025 by an ILAC-MRA signatory, or by a national metrology institute (NMI) or the OEM in accordance with approved data. What all of these have in common is a chain of traceability that leads back to national or international standards.
Traceability is what makes a calibration meaningful: the measurement on the certificate can be traced, step by step, back to a reference standard maintained by an authoritative body. An auditor can follow that chain. A tool calibration that cannot be traced to the standard used is worth little more than a sticker.
The wedge: expired calibrated tools must not go out
All of this traceability becomes operational at the moment a mechanic tries to issue the tool. If an item is calibration-controlled and its valid-use window is expired, it must not leave the store — and that cannot depend on someone noticing a colour or reading a banner.
That is the only-we invariant in Aviamatic's design: expired calibrated tools cannot be issued, including by supervisor override. Alongside it, the calibration record and the standard used live in one auditable place, so the traceability an auditor asks about is answerable in minutes rather than reconstructed from scattered certificates.
An honest boundary: we record, we do not calibrate
Notably, calibration servicing is not a Part-145 privilege held by the maintenance organisation itself; it is a supplier function under the quality system (145.A.65). The same boundary applies to Aviamatic: we do not perform calibration, and we are not a calibration laboratory.
Aviamatic records the intervals, the calibration events, the certificates, and the standards used, and it enforces the lockout at issue time. The actual calibration — performed by an ISO/IEC 17025-accredited lab, NMI, or OEM per approved data — stays with the supplier, and the decision-making stays with your organisation.