EASA Form 1
Michael Malone
(HoD) at Part 21 Design International Limited (Part of STS)
Why PROTOTYPE Status Can Create Problems
When a modification is installed on an aircraft, the focus is on embodiment, certification and return to operation. The paperwork is reviewed, the records are closed, and the aircraft moves on.
Years later, the same modification may be reviewed again. The aircraft may be changing operator, undergoing a lease return, being prepared for sale, entering a new maintenance programme or simply going through a detailed records audit. It is often at this point that an overlooked detail surfaces: a component carrying an EASA Form 1 marked PROTOTYPE.
The part may have been installed correctly. The aircraft may have been flying for years without issue. Yet questions regarding approval status, certification pathway and supporting documentation can suddenly become highly relevant – and, depending on how far back the approval trail needs to be reconstructed, disproportionately time-consuming to resolve.
Understanding what PROTOTYPE status means, and how to resolve it, is the kind of knowledge that costs nothing to have and can prevent significant disruption when it is eventually needed.
NEW vs PROTOTYPE: The Distinction That Matters
Most aviation professionals know the EASA Form 1 in its standard form. A new part arrives, Box 11 reads NEW, and the part is installed and enters service. That is the straightforward case.
PROTOTYPE status is different. When Box 11 is marked PROTOTYPE, the part has been manufactured against design data that has not yet received formal EASA approval. This is a recognised and legitimate stage of the modification development process – it allows parts to be produced and fitted for evaluation, testing or trial embodiment purposes. However, the certification pathway remains incomplete until the associated design approval is finalised and the part is appropriately re-certified.
The distinction may appear administrative. In practice, it represents the difference between a fully approved modification and one that is still progressing through the regulatory process. For any organisation reviewing technical records years after installation, recognising that distinction can be critical.
Three fields to check on every Form 1:
These three fields provide the first indication that further investigation may be required.
Why Issues Surface Years Later
The most common misconception surrounding PROTOTYPE parts is that the issue would have been apparent at the time of installation. In practice, many questions only emerge much later.
Aircraft records pass through multiple custodians over their operational life. Operators change. Modifications are reviewed by new engineering teams. Documentation packages are transferred, archived and reassembled. During that process, a technical team may encounter a modification package and ask a straightforward question: has the certification pathway been fully completed?
If the evidence cannot be clearly demonstrated, the reviewing organisation must establish whether design approval was ultimately granted, whether re-certification from PROTOTYPE to NEW occurred, whether continuing airworthiness records were updated appropriately, and whether the approval basis remains fully traceable. The technical challenge is often not the modification itself. The challenge is reconstructing the certification history.
The Critical Relationship Between 21J and 21G
Resolving PROTOTYPE status is primarily the responsibility of the organisations involved in the original design and production approval. The Part 21J Design Organisation Approval (DOA) holder is responsible for developing and securing approval of the design data. The Part 21G Production Organisation Approval (POA) holder is then responsible for re-certifying the part from PROTOTYPE to NEW, provided the approved design remains unchanged from the manufactured configuration.
EASA requires formally documented coordination arrangements between these two organisations. Without that framework in place, responsibilities become unclear and resolution becomes significantly more complicated. Many delays occur not because the technical solution is difficult, but because multiple organisations must reconstruct historical approval activity and establish who is responsible for the next step.
This interface between design and production is where certification programmes most commonly stall. Ensuring it is properly structured from the outset – and that both organisations have a clear, documented understanding of their respective responsibilities – is one of the most effective ways to prevent issues from becoming protracted. When certification, production and continuing airworthiness activities are managed by separate organisations without clear interface arrangements, reducing that coordination complexity is frequently more valuable than solving the underlying technical question.
Figure 1: The certification pathway from PROTOTYPE through design approval, re-certification to NEW and approved service entry
Five Checks During Any Records Review
Whether reviewing an aircraft before purchase, preparing for a lease return, supporting a CAMO audit or simply reviewing modification records, five checks can help identify potential issues before they become programme-critical.
| # | Check |
|---|---|
| 1 | Review Box 11 on all modification Form 1s. Does it show NEW or PROTOTYPE? |
| 2 | If PROTOTYPE appears, establish whether design approval was subsequently granted and by whom. |
| 3 | Confirm whether formal re-certification from PROTOTYPE to NEW was completed by the Part 21G POA. |
| 4 | Verify that a documented coordination arrangement existed between the 21J and 21G organisations. |
| 5 | Confirm that continuing airworthiness records accurately reflect the approved configuration and that CAMO embodiment is complete. |
A Final Thought
Most certification issues are identified and resolved during the modification programme itself. PROTOTYPE status is different. In many cases it remains invisible until years later, when a technical team reviewing aircraft records asks questions that nobody has needed to answer for a long time.
It is a relatively uncommon issue. But when discovered late, it can create disproportionate complexity – particularly when the organisations originally responsible for closing the approval loop are no longer easily contactable, or when the documentation trail has become difficult to reconstruct.
STS Part 21 International (EASA.21J.719) and STS CAMO operate as a connected programme within the same organisational structure. For lessors and operators dealing with a PROTOTYPE status question – whether current or historical – that means one point of contact covering approval strategy, re-certification coordination and airworthiness embodiment. That makes it worth understanding before it appears in your next records review.
About The Author
Michael Malone is Head of Design (HoD) at STS Part 21 International, the dedicated Part 21 Design and Engineering division of Shannon Technical Services. STS holds EASA Design Organisation Approval EASA.21J.719 and provides certified modification, repair, and engineering solutions for aircraft lessors and operators worldwide. Offices in Shannon, Malta and Singapore.
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