---
title: "Part-145 Maintenance Data and Performance · Avioverse"
description: "Part-145 in practice: current maintenance data (145.A.45), classifying and accepting components (145.A.42), tools and calibration, and performing maintenance."
url: "https://avioverse.aero/guides/easa-part-145-maintenance-data-performance"
---

# Part-145 Maintenance Data and Performance

Part-145 in practice: current maintenance data (145.A.45), classifying and accepting components (145.A.42), tools and calibration, and performing maintenance.

[Dionysis Kefalas](https://avioverse.aero/articles/author/dennis-kefalas) 12 Jun 2026 Updated 21 Oct 2026 8 min read For Part-145 and CAMO staff

Part 3 of 9 in EASA Part-145 Maintenance Organisation Show parts Hide parts

1. 1 [Part-145: The Approved Maintenance Organisation](https://avioverse.aero/guides/easa-part-145-approved-maintenance-organisation)
2. 2 [Part-145 Certifying and Support Staff](https://avioverse.aero/guides/easa-part-145-certifying-staff-personnel)
3. 3 Part-145 Maintenance Data and Performance
4. 4 [Part-145 Maintenance Certification and Records](https://avioverse.aero/guides/easa-part-145-certification-of-maintenance-records)
5. 5 [The Maintenance Organisation Exposition (MOE)](https://avioverse.aero/guides/easa-part-145-maintenance-organisation-exposition)
6. 6 [Part-145 Tool Control and Calibration (145.A.40)](https://avioverse.aero/guides/part-145-tool-control-calibration-145-a-40)
7. 7 [Receiving Inspection of Aircraft Parts: 145.A.42](https://avioverse.aero/guides/receiving-inspection-aircraft-parts-145-a-42)
8. 8 [Part-145 Approved Supplier List and Evaluation](https://avioverse.aero/guides/part-145-supplier-evaluation-approved-supplier-list)
9. 9 [Part-145 Parts Storage, Shelf Life and ESD](https://avioverse.aero/guides/part-145-parts-storage-shelf-life-esd)

Quotes checked on 24 Sep 2026 against EASA Easy Access Rules for Continuing Airworthiness (Regulation (EU) No 1321/2014) — 2 Sep 2025 revision.

On this page

## The inputs to the work

The work card and the component on the bench are only as good as the data, the release, and the tools behind them. This page is those Part-145 rules: maintenance data, components, tools, planning, and the performance of the maintenance.

## Working from current data

[145.A.45 (full rule text)](https://avioverse.aero/regulations/easa/continuing-airworthiness/part-145/section-a-technical-and-organisation-requirements/145-a-45) Maintenance data

> (a) The organisation shall hold and use applicable current maintenance data which is necessary
>
> in the performance of maintenance, including modifications and repairs. “Applicable” means
>
> relevant to any aircraft, component or process specified in the organisation’s terms of approval
>
> and in any associated capability list.
>
> In the case of maintenance data provided by the person or organisation requesting the
>
> maintenance, the organisation shall hold such data when the work is in progress, with the
>
> exception of the need to comply with point 145.A.55(a)(3).
>
> (b) Applicable maintenance data is the data specified in point M.A.401(b) of Annex I (Part-M) or
>
> in point ML.A.401(b) of Annex Vb (Part-ML), as applicable.
>
> (c) The organisation shall establish procedures to ensure that if inaccurate, incomplete or
>
> ambiguous procedure, practice, information or maintenance instruction is found in the
>
> maintenance data used by maintenance personnel, it is recorded as part of the internal safety
>
> reporting scheme referred to in point 145.A.202 and notified to the author of the maintenance
>
> data.
>
> (d) The organisation may only modify maintenance instructions in accordance with a procedure
>
> that is specified in the MOE. With respect to changes to maintenance instructions, the
>
> organisation shall demonstrate that they result in equivalent or improved maintenance standards,
>
> and shall inform the author of the maintenance instructions of such changes. For the purposes of
>
> this point, “maintenance instructions” mean instructions on how to carry out a particular
>
> maintenance task; they exclude the engineering design of repairs and modifications.
>
> \[…]
>
> (e) The organisation shall provide a common work card or worksheet system to be used throughout
>
> the relevant parts of the organisation. In addition, the organisation shall either accurately
>
> transcribe the maintenance data referred to in points (b) and (d) onto such work cards or
>
> worksheets, or make precise reference to the particular maintenance task or tasks contained in
>
> that maintenance data.
>
> \[…]
>
> (g) The organisation shall establish a procedure to ensure that maintenance data it controls is
>
> kept up to date. In the case of operator/customer controlled and provided maintenance data, the
>
> organisation shall be able to show that either it has written confirmation from the
>
> operator/customer that all such maintenance data is up to date or it has work orders specifying
>
> the amendment status of the maintenance data to be used or it can show that it is on the
>
> operator/customer maintenance data amendment list.

Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision.

Point (d) is a change to maintenance instructions. Point (e) is the common work card or worksheet system: transcribe, or make precise reference. Point (g) is maintenance data the organisation controls, and operator/customer controlled and provided maintenance data.

## Components, parts and materials

[145.A.42 (full rule text)](https://avioverse.aero/regulations/easa/continuing-airworthiness/part-145/section-a-technical-and-organisation-requirements/145-a-42) Components

> (a) Classification of components. All components shall be classified into the following
>
> categories:
>
> (i) Components which are in a satisfactory condition, released on an EASA Form 1 or equivalent
>
> and marked in accordance with Subpart Q of Annex I (Part 21) or, as applicable, Subpart Q of
>
> Section A of Annex Ib (Part 21 Light) to Regulation (EU) No 748/2012, unless otherwise specified
>
> in point 21.A.307 of Annex I (Part 21) or point 21L.A.193 of Annex Ib (Part 21 Light) to
>
> Regulation (EU) No 748/2012, in point M.A.502 of Annex I (Part-M), in point ML.A.502 of Annex
>
> III (Part-ML), or in this Annex (Part-145).
>
> (ii) Unserviceable components which shall be maintained in accordance with this Regulation.
>
> (iii) Components categorised as unsalvageable because they have reached their mandatory life
>
> limitation or contain a non-repairable defect.
>
> (iv) Standard parts used on an aircraft, engine, propeller or other aircraft component when
>
> specified in the maintenance data and accompanied by evidence of conformity traceable to the
>
> applicable standard.
>
> (v) Material, both raw and consumable, used in the course of maintenance when the organisation
>
> is satisfied that the material meets the required specification and has appropriate
>
> traceability. All material shall be accompanied by documentation clearly relating to the
>
> particular material and containing a conformity to specification statement as well as the
>
> manufacturing and supplier source.
>
> (b) Components, standard parts and materials for installation
>
> (i) The organisation shall establish procedures for the acceptance of components, standard parts
>
> and materials for installation to ensure that components, standard parts and materials are in
>
> satisfactory condition and meet the applicable requirements of point (a).
>
> (ii) The organisation shall establish procedures to ensure that components, standard parts and
>
> materials shall only be installed on an aircraft or a component when they are in satisfactory
>
> condition, meet the applicable requirements of point (a) and the applicable maintenance data
>
> specifies the particular component, standard part or material.
>
> \[…]
>
> (c) Segregation of components
>
> (i) Unserviceable and unsalvageable components shall be segregated from serviceable components,
>
> standards parts and materials.
>
> (ii) Unsalvageable components shall not be permitted to re-enter the component supply system,
>
> unless mandatory life limitation have been extended or a repair solution has been approved in
>
> accordance with Regulation (EU) No 748/2012.

Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision.

Category (i) is a component in a satisfactory condition, released on an EASA Form 1 or equivalent. That release is the subject of the [next guide](https://avioverse.aero/guides/easa-part-145-certification-of-maintenance-records). Points (b)(i) and (b)(ii) are the acceptance procedure and the installation procedure. Point (c)(i) is the segregation.

## Tools, equipment and planning

[145.A.40 (full rule text)](https://avioverse.aero/regulations/easa/continuing-airworthiness/part-145/section-a-technical-and-organisation-requirements/145-a-40) Equipment and tools

> (a) The organisation shall have available and use the necessary equipment and tools to perform
>
> the approved scope of work.
>
> (i) Where the manufacturer specifies a particular tool or equipment, the organisation shall use
>
> that tool or equipment, unless the use of alternative tooling or equipment is agreed by the
>
> competent authority via procedures specified in the exposition.
>
> \[…]
>
> (b) The organisation shall ensure that all tools, equipment and particularly test equipment, as
>
> appropriate, are controlled and calibrated according to an officially recognised standard at a
>
> frequency to ensure serviceability and accuracy. Records of such calibrations and traceability
>
> to the standard used shall be kept by the organisation.

Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision.

Point (a)(i) is a particular tool or equipment the manufacturer specifies. Point (b) is calibration and traceability. The register, the calibration interval and what to do when a tool is overdue are in [Tool Control in Aviation Maintenance: 145.A.40 Calibration](https://avioverse.aero/guides/part-145-tool-control-calibration-145-a-40).

[145.A.47 (full rule text)](https://avioverse.aero/regulations/easa/continuing-airworthiness/part-145/section-a-technical-and-organisation-requirements/145-a-47) Production planning

> (a) The organisation shall have a system appropriate to the amount and complexity of work to
>
> plan the availability of all necessary personnel, tools, equipment, material, maintenance data
>
> and facilities in order to ensure the safe completion of the maintenance work.
>
> (b) As part of the management system, the planning of maintenance tasks, and the organising of
>
> shifts, shall take into account human performance limitations, including the threat of fatigue
>
> for maintenance personnel.
>
> (c) When it is required to hand over the continuation or completion of maintenance tasks for
>
> reasons of a shift or personnel changeover, relevant information shall be adequately
>
> communicated between outgoing and incoming personnel.
>
> \[…]

Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision.

Point (b) is human performance limitations, including the threat of fatigue. Point (c) is a shift or personnel changeover.

## Performing the maintenance

[145.A.48 (full rule text)](https://avioverse.aero/regulations/easa/continuing-airworthiness/part-145/section-a-technical-and-organisation-requirements/145-a-48) Performance of maintenance

> (a) The organisation may only carry out maintenance on an aircraft or component for which it is
>
> approved when all the necessary facilities, equipment, tooling, material, maintenance data and
>
> personnel are available.
>
> (b) The organisation shall be responsible for the maintenance that is performed within the scope
>
> of its approval.
>
> (c) The organisation shall ensure that:
>
> (1) after the completion of the maintenance, a general verification is carried out to ensure
>
> that the aircraft or component is clear of all tools, equipment and any extraneous parts or
>
> material, and that all access panels that were removed have been refitted;
>
> (2) an error-capturing method is implemented after the performance of any critical maintenance
>
> task;
>
> (3) the risk of errors during maintenance and the risk of errors being repeated in identical
>
> maintenance tasks are minimised;
>
> (4) damage is assessed, and modifications and repairs are carried out using the data specified
>
> in point M.A.304 of Annex I (Part-M) or point ML.A.304 of Annex Vb (Part-ML), as applicable;
>
> (5) the assessment of aircraft defects is carried out in accordance with point M.A.403(b) of
>
> Annex I (Part-M) or ML.A.403(b) of Annex Vb (Part-ML), as applicable.

Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision.

Point (c)(1) is the general verification. Point (c)(2) is an error-capturing method after any critical maintenance task. Point (c)(3) is errors being repeated in identical maintenance tasks.

## Next

The certificate of release to service, and the records that support it, are covered in [Certification of Maintenance and Records](https://avioverse.aero/guides/easa-part-145-certification-of-maintenance-records).

## Where to read it yourself

These rules are 145.A.40, 145.A.42, 145.A.45, 145.A.47 and 145.A.48 in Annex II (Part-145) of Regulation (EU) No 1321/2014, in the EASA **Easy Access Rules for Continuing Airworthiness**, a free download. Every citation in this guide was checked against the **2025-09-02 revision**.

Educational content, not regulatory compliance advice. Verify against the current regulation text before relying on it.

## In this series

## Frequently asked questions

### What should a Part-145 organisation do with inaccurate maintenance data?

Under 145.A.45(c), the organisation must have procedures to record inaccurate, incomplete or ambiguous maintenance instructions or information through its internal safety reporting scheme and notify the data's author. This applies to problems found in the maintenance data used by its personnel.

### Can a Part-145 organisation modify maintenance instructions?

Only through a procedure specified in its maintenance organisation exposition, under 145.A.45(d). The organisation must demonstrate equivalent or improved maintenance standards and inform the instructions' author. This provision concerns instructions for carrying out a maintenance task, excluding engineering design of repairs and modifications.

### What work card system does Part-145 require?

Part-145 requires a common work card or worksheet system throughout the relevant parts of the organisation. The 145.A.45(e) provision covers accurate transcription of the relevant maintenance data onto those cards or precise references to the particular maintenance tasks in that data.

### How must Part-145 maintenance planning address fatigue and shift handovers?

Maintenance task planning and shift organisation must take account of human performance limitations, including fatigue, under 145.A.47(b). When a shift or personnel change requires work to be handed over, relevant information must be adequately communicated between outgoing and incoming personnel under point (c).

### What checks are required after critical maintenance tasks under Part-145?

145.A.48(c)(2) requires an error-capturing method after any critical maintenance task. Separately, after maintenance is completed, point (c)(1) requires a general verification that the aircraft or component is clear of tools, equipment and extraneous material, and that removed access panels have been refitted.

## Related

- [EASA Part-145 Explained: The Approved Maintenance Organisation Guide · 4 min](https://avioverse.aero/guides/easa-part-145-approved-maintenance-organisation)
- [Certifying Staff, Support Staff and Personnel under Part-145 Guide · 12 min](https://avioverse.aero/guides/easa-part-145-certifying-staff-personnel)
- [Certification of Maintenance and Records under Part-145 Guide · 6 min](https://avioverse.aero/guides/easa-part-145-certification-of-maintenance-records)
- [The Maintenance Organisation Exposition (MOE) Guide · 6 min](https://avioverse.aero/guides/easa-part-145-maintenance-organisation-exposition)
- [Tool Control in Aviation Maintenance: 145.A.40 Calibration Guide · 17 min](https://avioverse.aero/guides/part-145-tool-control-calibration-145-a-40)

Written by Dionysis Kefalas. Retired Hellenic Air Force Captain and founder of Avioverse. [About the author](https://avioverse.aero/articles/author/dennis-kefalas)

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