AML STC expansion
AML STC expansion compliance matrix support
This review prepares the compliance matrix that supports adding models to an approved model list STC. A certification engineer runs it before the expansion is submitted, once the added models and their applicability are defined. It reads each matrix line's requirement, means of compliance, and cited evidence, then checks whether the original basis still holds for the new applicability or whether the added model needs fresh substantiation. You get a gap assessment on the matrix, a trace map from each requirement to current evidence, and a closure plan for the entries the expansion does not yet cover.
When this review is needed
- New aircraft models are being added to an AML STC and the compliance matrix has to extend to them.
- The original evidence has aged and the holder needs to confirm it still supports the expanded model list.
- An added model differs enough that some matrix entries need fresh means of compliance.
- Several past amendments left the matrix inconsistent and the expansion is the moment to reconcile it.
The problem
An AML STC grows model by model, and the compliance matrix is supposed to carry the original substantiation across each addition. It rarely does cleanly. A new model's installation differs from the ones the evidence was taken on, an environmental qualification no longer bounds the added aircraft's conditions, or a matrix line cites evidence that the base STC has since superseded. Each addition inherits the assumption that the original compliance still applies, and confirming that assumption for the new applicability is the work the expansion skips at its peril.
What gets reviewed
- Each matrix requirement against the applicability of the added models
- Means of compliance carried from the base STC checked for the new installations
- Cited evidence confirmed as current and not superseded by the base STC
- Qualification bounds, environmental and functional, against the added aircraft's conditions
- Entries needing fresh substantiation for a model that differs from the original basis
- Consistency across matrix entries left by prior amendments
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
- Each carried means of compliance still applies to the added model's installation
- Cited evidence is the current revision and has not been superseded on the base STC
- Environmental qualification bounds the conditions the added aircraft imposes
- Requirements new to the added model have a defined means of compliance, not an inherited one
- The matrix is internally consistent across the entries prior amendments touched
Evidence normally required
- The current compliance matrix for the AML STC
- The added models and their applicability and installation differences
- The evidence cited against each matrix entry
- Qualification data, environmental and functional, with its stated bounds
- The certification basis for the base STC and the expansion
Common discrepancies
- A carried means of compliance that no longer applies to the added installation
- A matrix line citing evidence the base STC has superseded
- Environmental qualification that does not bound the added aircraft's conditions
- Inconsistent entries left across earlier model additions
What is at stake
A matrix that carries a compliance claim onto a model it no longer bounds sends the expansion into review resting on evidence that does not reach the added aircraft. The authority finds the entry that does not hold, and the added model either drops from the expansion or waits for substantiation that was never scoped. Reconciling the matrix after the fact, across an approved model list, is slower than confirming each carried claim before submittal.
How the work runs
Define the added applicability
Establish the added models and how their installations differ from the original basis.
Test the carried compliance
Check each carried means of compliance and its evidence against the new applicability.
Confirm qualification bounds
Verify environmental and functional qualification bounds the conditions the added aircraft imposes.
Scope the substantiation
Plan fresh means of compliance for the entries the expansion does not yet cover.
What the buyer receives
- A gap assessment on the matrix against the added model list
- A trace map from each requirement to current, applicable evidence
- A closure plan for the entries the expansion does not yet substantiate
Who uses the output
- Certification engineers confirming the matrix reaches every added model
- STC holders deciding which added models are ready and which need substantiation
- Program managers scoping the substantiation the expansion still requires
How the work fits into the transaction or program
The compliance matrix is the spine of an AML STC expansion, the record that says the original substantiation carries to each new model. This review tests that carry-over before the expansion is submitted, so the added models rest on evidence that actually reaches them, and it feeds the certification plan the expansion is built around.
Start with a single asset
Reduce finding cycles by checking the package first.
Jurisdiction-specific considerations
FAA and EASA maintain their own approved model lists and validate expansions on their own terms, so the review notes where a matrix entry accepted on one authority's model list needs additional substantiation before the other will extend the STC to the same aircraft.
Regulatory limits
The review confirms the matrix's means of compliance and evidence hold for the added models. It does not approve the expansion, extend the model list, sign a compliance finding, or make an airworthiness determination on any added aircraft.
What this review does not cover
- Producing the substantiation for a model the matrix does not yet cover
- Extending the approved model list on the authority's behalf
- Signing a compliance finding for an added model or extending the STC
Specific to this review
- An AML STC inherits the assumption that original compliance carries to each new model, and that assumption is exactly what a differing installation quietly breaks.
- Environmental qualification bounds are a frequent break point, because an added aircraft can impose conditions the original test never covered.
- Evidence superseded on the base STC can still be cited in the matrix for an added model, so currency is checked against the base STC, not the matrix alone.
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.
SAE International. Development assurance process at aircraft and system level, including requirements capture and validation.
Frequently asked questions
The base STC was already approved. Why re-examine the matrix for new models?
Approval of the base STC covered the models it was tested and substantiated on. An added model can differ enough that a carried compliance claim no longer applies, or an environmental qualification no longer bounds it. The review confirms each carried entry reaches the new aircraft and flags the ones that need fresh substantiation before the expansion is submitted.
Relevant glossary terms
Related pages
Where this fits
Talk to an engineer who has done this work
We will walk through your current state, the records or evidence involved, and a scoped first engagement.
Talk through the aircraft, records, evidence, deadline, and next useful step.