Minor vs major modifications under EASA

What it means in practice

The minor-versus-major decision is a design approval question, not a workshop preference. The classification determines the approval path, the design substantiation route, the authority or DOA involvement needed, and the records that must support embodiment.

In practice, maintenance organisations may embody a modification only when approved data exists and the change is within the lawful approval route. The physical embodiment work does not give the maintenance organisation authority to classify the design change on its own unless it also holds the relevant design approval privilege under the applicable design framework.

Who it applies to

This distinction applies to design organisations, operators, CAMOs, and maintenance organisations involved in design change embodiment, records, and continued airworthiness follow-up. It matters whenever someone proposes changing the approved aircraft configuration rather than simply restoring it.

It also affects the continuing airworthiness side because the resulting approved data, ICA updates, and configuration records must be taken into the AMP, records, and maintenance system after embodiment.

What EASA says

Point 21.A.91 sets the classification rule. A modification is minor only if it has no appreciable effect on mass, balance, structural strength, reliability, operational characteristics, environmental characteristics, or other characteristics affecting airworthiness or product environmental protection. If it has an appreciable effect, it is major. That means the classification is anchored in approved design impact, not in how easy or difficult the embodiment work appears at maintenance level.

Common mistakes

The most common mistake is assuming the maintenance organisation can simply decide that a change is minor because it looks straightforward. The classification belongs to the design approval route.

Another mistake is confusing modifications with repairs. Both can change the configuration, but the classification rules and approval paths are different. A third mistake is embodying a change without checking the continuing airworthiness consequences, including records, ICA, mass and balance, and future maintenance tasks.