Certification evidence
Qualification by similarity justification evidence review for DO-160G
This review is for equipment suppliers, avionics suppliers, Engineering teams responsible for qualification by similarity justification. It is triggered by requalification decision after design change. EE checks prior qualification report, its categories, delta analysis of design differences, plus the governing plan or application, against DO-160G. Discrepancies include missing source records, mismatched configuration, unsupported assumptions, or similarity claimed across different mounting or cooling regimes that change vibration. Output includes Qualification by similarity justification exception register, Claim to evidence map, Reviewer question list.
When this review is needed
- The team is preparing for requalification decision after design change.
- Supplier records and applicant records must be reconciled.
- Program leads need to know which findings could block the next gate.
- A proposed means of compliance depends on evidence reuse, analysis, or rationale.
The problem
Reviewers need to reconstruct the path from final claim to source data. For qualification by similarity justification, weak files usually show similarity claimed across different mounting or cooling regimes that change vibration, then reveal revision drift or unclosed assumptions.
What gets reviewed
- Review prior qualification report against the configuration, installation, or claim under review.
- Compare its categories against the configuration, installation, or claim under review.
- Trace delta analysis of design differences against the configuration, installation, or claim under review.
- Challenge environment comparison between old against the configuration, installation, or claim under review.
- Reconcile new installations against the configuration, installation, or claim under review.
- Confirm specific sections claimed by similarity versus retest. against the configuration, installation, or claim under review.
What gets validated
- Pass check: prior qualification report must match the released configuration and the claimed means of compliance.
- Configuration check: its categories must match the released configuration and the claimed means of compliance.
- Trace check: delta analysis of design differences must match the released configuration and the claimed means of compliance.
- Rationale check: environment comparison between old must match the released configuration and the claimed means of compliance.
- Closure check: new installations must match the released configuration and the claimed means of compliance.
Evidence normally required
- Controlled prior qualification report
- Released its categories
- Signed delta analysis of design differences
- Current environment comparison between old
- Archived new installations
- Supplier specific sections claimed by similarity versus retest.
Common discrepancies
- Gap: similarity claimed across different mounting or cooling regimes that change vibration.
- Mismatch: thermal exposure.
- Unsupported claim: delta analysis that lists differences without assessing them.
- Late issue: prior reports referenced that the applicant cannot produce.
What is at stake
An unresolved gap can become a finding, a deferred submittal, or a narrower claim. Missing support for thermal exposure often affects several records at once.
Move from findings to resolution
Identify gaps against the means of compliance.
How the work runs
Frame Qualification Similarity
Confirm the exact event, affected file set, buyer role, and decision standard before any prior qualification report is treated as sufficient.
Trace Review Evidence
Walk the named evidence from index entry to source artifact and mark where the trail supports, conflicts with, or fails to answer the page-specific question.
Sort Certification Delta
Group exceptions by closure route: document retrieval, data correction, engineering disposition, authority response, or contractual decision.
Package Behind Claim
Deliver the exception list, evidence map, and owner sequence in a form that can move directly into remediation, submittal cleanup, or transaction negotiation.
What the buyer receives
- Qualification by similarity justification exception register
- Claim to evidence map
- Reviewer question list
- Closure action plan
Who uses the output
- qualification engineer assign closure actions from the exception register.
- hardware lead use the map to locate source evidence.
- certification liaison decide what can proceed and what must wait.
How the work fits into the transaction or program
Does a similarity justification actually bound the new article and installation with previous test evidence, or is it a resemblance argument. The evidence set centers on the prior qualification report and its categories, a delta analysis of design differences (circuit, packaging, mounting, cooling), environment comparison between old and new installations, and the specific sections claimed by similarity versus retest. The likely weak points are similarity claimed across different mounting or cooling regimes that change vibration and thermal exposure, delta analysis that lists differences without assessing them, and prior reports referenced that the applicant cannot produce. The output gives the qualification engineer a cleanup register for Qualification by similarity justification before requalification decision after design change.
Start with a single asset
Confirm requirements trace through verification.
Regulatory limits
This review is not an approval activity. Final findings, acceptance, installation approval, and airworthiness decisions remain with the responsible applicant, authorized representatives, and authorities.
What this review does not cover
- Authority negotiations as decision maker
- Compliance finding approval
- Test execution or article build
- Operator airworthiness release
Specific to this review
- Configuration identity matters because evidence from another baseline may prove a different article, load, or installation.
- A useful trail names the source record, revision, owner, and closure decision for each claim.
- The exception list separates document-control cleanup from gaps that need engineering substantiation.
- The finding pattern for this page is specific: similarity claimed across different mounting or cooling regimes that change vibration changes the strength of the certification argument.
- The scope uses the Qualification Similarity Justification Review question as the control point, so the review stays tied to Requalification decision after design change and the buyer decision behind it.
- The evidence starts with Prior qualification report and follows Evidence 160g Certification Delta references until every exception has a source location and a reason code.
- The finding logic separates missing paperwork, conflicting status, stale revision data, and unsupported disposition because each class closes through a different owner.
- The timing matters for qualification engineer: the output is useful only if the unresolved items are visible before acceptance, submittal, handback, or negotiation pressure fixes the sequence.
- The boundary control keeps Analysis Behind Claim Audit questions in the records or certification lane and sends technical acceptance issues to the authorized people who own them.
- The handoff value comes from Qualification by similarity justification exception register; it gives the next reviewer a precise map instead of another broad request for a better file.
Sources
Frequently asked questions
What makes this evidence review different from a general file audit?
The scope is tied to qualification similarity justification review and to the decision named in the request. A general audit can list weak records; this pass ranks the gaps by whether they block requalification decision after design change or can be closed later without changing the decision.
What evidence has to be available before this work starts?
The starting point is prior qualification report, the current status source, and any index or matrix that tells reviewers where the supporting artifact should live. Missing inputs are logged as findings rather than filled with assumptions.
Who decides whether an open item is acceptable?
The review explains what the evidence supports and gives qualification engineer a closure path. Acceptance remains with the buyer, operator, authority, delegated engineer, or authorized person responsible for the underlying airworthiness or certification decision.
Relevant glossary terms
Related pages
Where this fits
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