Certification basis
Closing coverage gaps against the STC certification basis
This closure work finds the places where an STC certification basis is not fully covered by the compliance data the program planned. It is run for the modifier when a basis requirement, a special condition, or an equivalent-level-of-safety item has no corresponding line in the compliance plan and would otherwise reach a reviewer as a silent gap. The work walks the full basis, marks each requirement that has no planned means of compliance, and pairs it with a method and an evidence owner. You receive a coverage map from basis to compliance data, an evidence request list for the newly assigned items, and a disposition package that shows every basis requirement accounted for.
When this review is needed
- A special condition or equivalent-safety finding was added to the basis but never flowed into the compliance plan.
- The basis was updated mid-program and the new requirements were not mapped to means of compliance.
- A reviewer's basis walkdown found a regulation with no corresponding compliance line.
- The compliance plan was built from a checklist that predates the final agreed basis.
The problem
The certification basis is the list of requirements the modification has to meet, and the compliance plan is how each one gets met. When the two are built at different times or by different people, requirements fall through the gap between them. A special condition gets negotiated late, the basis document is revised, and the compliance plan keeps running on the earlier assumption. The requirement is real and applicable, but no method, no evidence, and no owner ever attached to it, so it is invisible until someone reads the basis against the plan.
What gets reviewed
- The full certification basis, including special conditions and equivalent-safety findings, walked against the compliance plan
- Each basis requirement with no planned means of compliance marked as uncovered
- A means of compliance assigned to every uncovered requirement
- An evidence owner named for each newly mapped item
- The coverage map reconciled so no basis requirement is unaddressed
What gets validated
- Every requirement in the agreed basis appears on the compliance plan with a method
- Special conditions and equivalent-safety findings are covered, not just the base regulations
- The means of compliance assigned to each item is appropriate to the requirement it meets
- Newly mapped items carry an owner who can produce the evidence
- The basis version the coverage is checked against is the final agreed one
Evidence normally required
- The agreed certification basis with any special conditions and findings
- The current compliance plan or checklist
- Correspondence recording basis changes negotiated during the program
- The means-of-compliance definitions the program is using
- The engineering owners available to take newly mapped items
Common discrepancies
- A special condition present in the basis but absent from the compliance plan
- A basis revision whose added requirements never reached the plan
- A requirement covered by a method that does not actually satisfy it
- A compliance plan built to a checklist that predates the final basis
What is at stake
An uncovered basis requirement is the kind of finding that resets a schedule, because closing it can mean new analysis or test rather than paperwork. Discovered by a reviewer, it signals that the basis was not fully worked, which prompts a deeper look at the rest of the coverage. Left unresolved, it blocks the finding of compliance the whole submittal depends on.
Move from findings to resolution
Identify the missing data behind the finding.
How the work runs
Fix the basis version
Confirm the agreed basis, including all special conditions and findings, as the checklist to work against.
Walk plan against basis
Compare each basis requirement to the compliance plan and mark the ones with no method.
Map and assign
Give every uncovered requirement a means of compliance and an evidence owner.
Reconcile the coverage
Produce a map showing the full basis addressed and package the open items.
What the buyer receives
- A coverage map linking every basis requirement to a planned means of compliance
- An evidence request list for the requirements newly assigned an owner
- A disposition package showing the full basis accounted for
Who uses the output
- Certification leads confirming the basis is fully covered before the finding of compliance
- Engineering owners taking on the newly mapped requirements
- Program managers scoping the work a late-discovered basis item creates
How the work fits into the transaction or program
Basis coverage is the foundation the whole compliance demonstration rests on, so it has to be complete before matrix citations, verification trace, and finding closure mean anything. This work runs early in closure, ahead of the detailed evidence checks, so a gap that needs new analysis surfaces while there is still schedule to absorb it.
Start with a single asset
Confirm each requirement maps to substantiating evidence.
Jurisdiction-specific considerations
Each authority sets its own basis, so a modification certified under one and validated by another can carry basis items the original program never planned for. The coverage work distinguishes the requirements common to both from those unique to the validating authority, so the second submission does not open with uncovered items.
Regulatory limits
This work maps the basis to planned means of compliance and assigns owners. It does not agree the basis with the authority, judge whether a chosen method is acceptable, approve the modification, or grant the STC. Basis agreement and acceptance of the method remain the authority's role.
What this review does not cover
- Negotiating or amending the certification basis with the authority
- Producing the analysis or test evidence for a newly mapped requirement
- Any finding that a means of compliance is acceptable
Specific to this review
- The gap between basis and plan opens most often around special conditions, because they are added by negotiation after the plan is drafted.
- An uncovered basis item can be the costliest finding on a program, since closing it may require new test rather than recovered paperwork.
- A compliance plan can look complete on its own terms and still miss requirements, because completeness is only meaningful against the current basis.
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. FAA type certification process, certification basis establishment, and compliance findings.
European Union / EASA. EASA design and production certification, STCs, ETSO authorizations, and EASA Form 1 release.
Frequently asked questions
How is a coverage gap different from a missing means of compliance?
A coverage gap is a basis requirement that never entered the compliance plan at all, so nobody was even tracking it. A missing means of compliance is a requirement on the plan that has no assigned method. Coverage work finds the requirements the plan forgot; means-of-compliance work fixes the ones it acknowledged but left unmethoded.
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.