TSO authorization
Means-of-compliance map support for TSO authorization
A TSO means-of-compliance map review confirms that each requirement is assigned a method the FAA will accept and that the method leads to real evidence rather than an intention. Equipment suppliers use it before submission, so no requirement carries a method with nothing behind it. The work checks that test, analysis, inspection, or similarity is a valid choice for each requirement, that the evidence path is more than a placeholder, and that the assignments hold together across related requirements. You get a gap assessment on the assignments, a map from each requirement through its method to its evidence, and a closure plan for the requirements whose path does not yet exist.
When this review is needed
- The requirement set is defined and each requirement now needs a method assigned before any evidence is generated.
- A method chosen by similarity leans on a claim the reference article does not actually support.
- A requirement was assigned analysis to save schedule, and it needs checking that analysis is a valid method for it.
- The map was inherited from a prior program and has to be revalidated against this article's requirements.
The problem
Assigning a method is quick; making it stand up is not. A requirement can be marked as met by similarity or analysis to keep the schedule moving, and the choice reads fine on the map until a reviewer asks for the evidence the method implies. The map is where optimistic method choices hide, because it looks complete long before any of the assignments have been tested against real data.
What gets reviewed
- Each requirement checked for a valid method under the certification basis
- Similarity claims tested against what the reference article actually establishes
- Analysis assignments checked for the data and assumptions they depend on
- Test assignments tied to the DO-160G, DO-178C, or DO-254 evidence they will produce
- The evidence path behind each method confirmed as real rather than a placeholder
- Consistency of method choices across requirements that share evidence
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
- Every requirement carries a method that is acceptable for that requirement under the basis
- Each similarity claim names a reference article and a shared attribute that genuinely supports it
- Analysis-based assignments identify the input data and assumptions the analysis will use
- Each assigned method resolves to an evidence item that exists or is scheduled, not a blank
- Requirements that draw on the same evidence use methods consistent with one another
Evidence normally required
- The requirement set for the article with the certification basis
- The current means-of-compliance assignments in whatever form they exist
- Reference articles and prior data underpinning any similarity claims
- The DO-160G, DO-178C, and DO-254 evidence the methods point to
- The program schedule so scheduled evidence can be distinguished from missing evidence
Common discrepancies
- A requirement assigned a method that the certification basis does not accept for it
- A similarity claim resting on a reference article that differs in the relevant respect
- An analysis assignment with no identified input data or stated assumptions
- A method marked complete whose evidence path ends in a placeholder
What is at stake
A requirement assigned a method with no evidence path is a finding waiting to be written, and it surfaces late because the map looked closed. A method the FAA does not accept for that requirement forces a switch to a costlier one after the schedule was built on the cheaper choice, and a similarity claim that does not hold sends the requirement back to test.
How the work runs
Read each assignment
Confirm the method chosen for each requirement is acceptable under the certification basis.
Test the weak methods
Stress the similarity and analysis claims against the data they actually rest on.
Trace to evidence
Follow each method to a real or scheduled evidence item and flag the placeholders.
Close the paths
List requirements with no evidence path and sequence the work to give them one.
What the buyer receives
- A gap assessment on the method assignments and their evidence paths
- A map tracing each requirement through its method to a named evidence item
- A closure plan for the requirements whose evidence path does not yet exist
Who uses the output
- Certification leads defending each method choice in front of the FAA
- Engineering owners deciding whether a weak similarity claim reverts to test
- Program managers seeing which method choices carry unfunded evidence work
How the work fits into the transaction or program
The map sits between the requirements and the evidence, translating what must be shown into how it will be shown. It follows requirements definition and precedes evidence generation, and the compliance matrix later confirms each mapped method actually produced the report it promised.
Start with a single asset
Reduce finding cycles by checking the package first.
Jurisdiction-specific considerations
Acceptable methods follow FAA guidance for the article's standard, so a method that is routine for one authority is not assumed acceptable here without checking. The map is validated against the FAA certification basis, and any later use for another authority is treated as a separate mapping exercise rather than a copy.
Regulatory limits
The review checks that each assigned method is valid and leads to evidence. It does not accept a method on the FAA's behalf, perform the compliance demonstration, or make a finding that a requirement is met.
What this review does not cover
- Running the tests or analyses the methods call for
- Obtaining FAA acceptance of a proposed method
- Authoring the requirement set the map assigns methods to
Specific to this review
- The map looks complete long before any assignment is proven, so method optimism is its characteristic failure mode.
- Similarity is the cheapest method to assign and the easiest to overreach: a reference article that differs in the one relevant attribute collapses the claim.
- A method the basis does not accept for a requirement is worse than a missing assignment, because the schedule was already built on it before anyone noticed.
Sources
U.S. Government (eCFR). Type certificates, STCs (Subpart E), TSO authorizations (Subpart O), PMA (Subpart K), and export airworthiness approvals (Subpart L).
RTCA. Environmental qualification test categories and procedures referenced by TSO and equipment qualification.
RTCA. Objectives and lifecycle data for airborne software assurance, by design assurance level (DAL A-E).
RTCA. Design assurance objectives and lifecycle data for airborne electronic hardware (FPGA/ASIC/PLD).
Federal Aviation Administration. FAA type certification process, certification basis establishment, and compliance findings.
Frequently asked questions
Can we lean on similarity to reduce testing?
Similarity is a valid method when the reference article genuinely shares the relevant attribute and its data supports the claim. The review tests each similarity claim against that standard, because one that does not hold sends the requirement back to test after the schedule assumed it was closed.
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.