AML STC expansion
AML STC expansion certification plan support
This review prepares the certification plan that frames an approved model list STC expansion, so its commitments match the data the program can actually deliver. A certification engineer runs it early, as the expansion is scoped, before the plan is agreed with the authority. It reads the stated basis, the areas the added models affect, and the review and evidence commitments, then checks each against what the package holds or can produce. You get a gap assessment on the plan, a trace map from each commitment to its intended evidence, and a closure plan for the promises the data does not yet support.
When this review is needed
- An AML STC expansion is being scoped and the certification plan has to set a basis the added models can meet.
- The plan is about to be agreed with the authority and the holder wants its commitments checked against deliverable data first.
- Prior expansions set precedents the new plan should follow and the holder needs the plan aligned to them.
- The added models affect areas the base STC did not, and the plan has to account for the new scope.
The problem
The certification plan is the program's contract with the authority, and once agreed, the program owns every commitment in it. A plan drafted optimistically, promising a means of compliance the added models cannot actually satisfy, or claiming the base STC's basis covers an affected area it never touched, sets the program up to miss its own commitments. Because the plan is agreed before most of the evidence exists, an unrealistic promise is easy to make and expensive to unwind once the authority is holding the program to it.
What gets reviewed
- The certification basis the plan proposes for the added models
- Areas the added models affect that the base STC did not cover
- Means of compliance committed against what the data can deliver
- Review and involvement commitments against the program's actual approach
- Alignment with precedents set by prior expansions on the same STC
- The evidence the plan implies must exist by each milestone
Scope this review
Tell us the asset, the event, and the evidence in scope, and we will outline a focused first engagement.
Identify what is missing against the means of compliance.
What gets validated
- The proposed basis actually covers the areas the added models affect
- Each committed means of compliance is one the added models can satisfy
- Review and involvement commitments match the program's real approach
- The plan does not promise coverage the data package cannot produce
- The plan is consistent with the basis and precedents of prior expansions
Evidence normally required
- The draft certification plan for the expansion
- The added models and the areas their installations affect
- The base STC certification basis and prior expansion plans
- The evidence and means of compliance the program intends to use
- The authority's expectations for the expansion, where known
Common discrepancies
- A committed means of compliance the added models cannot actually satisfy
- A basis claiming coverage of an area the added models newly affect
- A review commitment the program's approach does not match
- A plan inconsistent with the basis a prior expansion established
What is at stake
A plan that commits to coverage the data package cannot deliver forces the program to either produce evidence it never scoped or renegotiate the plan with the authority mid-program, both of which cost schedule the expansion did not budget. A basis that overreaches, claiming the original substantiation covers a newly affected area, collapses when the evidence for that area does not exist. Getting the plan realistic before it is agreed is far cheaper than amending it under scrutiny.
How the work runs
Scope the affected areas
Establish which areas the added models affect and whether the base STC basis covers them.
Test the commitments
Check each committed means of compliance against what the added models can satisfy.
Align to precedent
Confirm the plan is consistent with the basis and approach of prior expansions.
Right-size the plan
Plan the corrections that bring the commitments in line with deliverable data before it is agreed.
What the buyer receives
- A gap assessment on the plan against the deliverable data
- A trace map from each commitment to its intended evidence
- A closure plan for the commitments the data does not yet support
Who uses the output
- Certification leads confirming the plan is achievable before it is agreed
- STC holders committing to a basis they can meet across the added models
- Program managers scoping the work the plan's commitments will require
How the work fits into the transaction or program
The certification plan sets the frame the whole expansion works inside, so getting it realistic comes before the compliance matrix and the evidence are built out. This review tests the plan's commitments against deliverable data before it is agreed with the authority, so the program commits to a basis it can meet rather than one it will have to renegotiate.
Start with a single asset
Reduce finding cycles by checking the package first.
Jurisdiction-specific considerations
FAA and EASA agree certification plans on their own terms, and an expansion validated across both may need the plan framed to satisfy each authority's involvement and basis expectations, so the review notes where a single plan has to serve two authorities without over-committing to either.
Regulatory limits
The review confirms the plan's basis and commitments are achievable against the data. It does not agree the plan on the authority's behalf, set the certification basis, sign a compliance finding, or make an airworthiness determination.
What this review does not cover
- Negotiating the certification plan with the authority
- Setting the certification basis on the authority's behalf
- Signing the compliance finding the plan commits to, or amending the STC
Specific to this review
- The certification plan is agreed before most evidence exists, so an over-optimistic commitment is easy to make and becomes a binding obligation the program then has to meet.
- A basis that claims the original substantiation covers a newly affected area is a common overreach, because the added model touches something the base STC never did.
- Prior expansions on the same STC set precedents the authority expects the new plan to follow, and a plan that diverges without cause invites extra scrutiny.
Sources
U.S. Government (eCFR). Type certificates, STCs (Subpart E), TSO authorizations (Subpart O), PMA (Subpart K), and export airworthiness approvals (Subpart L).
Federal Aviation Administration. STC application process, certification basis, and continued airworthiness obligations of an STC holder.
European Union / EASA. EASA design and production certification, STCs, ETSO authorizations, and EASA Form 1 release.
Federal Aviation Administration. FAA type certification process, certification basis establishment, and compliance findings.
Frequently asked questions
Why review the plan before we agree it with the authority instead of after?
Once the plan is agreed, its commitments are binding and the program owns them, so an over-promise becomes work you must deliver or renegotiate under scrutiny. Reviewing the plan against deliverable data first lets you commit to a basis and means of compliance the added models can actually meet, which is far cheaper than amending an agreed plan mid-program.
Relevant glossary terms
Related pages
Where this fits
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