Configuration diligence
Verifying modification and STC status from data-room files
This review measures a seller's modification status report against the embodiment and approval evidence uploaded to the data room. For each sampled modification or STC it looks for the accomplishment record, the effectivity for this serial number, the approval basis, and the follow-on items: AFM supplements, ICA, and weight and balance amendments. It runs on the buyer's behalf while the room is open and questions still get answered. Results come back as a claimed-versus-supported matrix plus exceptions for negotiation.
When this review is needed
- The specification advertises value-adding STCs whose approval and embodiment files are absent from the index.
- A modification status report lists SB accomplishments the AD review will depend on.
- The buyer intends a registry transfer and needs to know which STCs hold acceptable approvals in the destination regime.
- Interior or connectivity modifications were installed under a prior operator and the paper moved with that operator.
The problem
Modification status reports mix three different claims, that a change was embodied, that it was approved, and that it applies to this serial number, and the evidence for each lives in different documents. Data rooms often carry the STC certificate but no embodiment record, or an embodiment entry with no approval basis, and the report flattens all of it into a single complied column that reads cleaner than the files beneath it.
What gets reviewed
- Sampled modifications traced to embodiment records with dates, locations, and certifying signatures
- Approval basis confirmed for each: STC, SB under the type design, or field approval, with the document in the room
- Effectivity verified against this serial number, since fleet-level reports smuggle in inapplicable lines
- Follow-on documents located: AFM supplements, ICA, wiring updates, and weight and balance amendments
- Removed or deactivated modifications checked for de-modification records
- The status report reconciled line by line for the sampled set
Scope this review
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What gets validated
- Embodiment entries exist in the maintenance record and identify the accomplishing organization
- Each STC certificate on file matches the installed configuration the embodiment record describes
- FAA Form 337 or EASA approval references are present where the change classification requires them
- AFM supplements and ICA cited by the approvals appear in the room at the correct revision
- Lines marked not applicable carry an effectivity basis rather than a bare assertion
Evidence normally required
- The modification and STC status report the seller represents
- Uploaded approval documents, embodiment records, and follow-on manuals
- The aircraft specification and equipment list for cross-reference
- Data-room index and Q&A history
Common discrepancies
- An STC advertised in the specification with no embodiment record anywhere in the uploads
- Interior modifications embodied under a lessee whose engineering files never reached the seller
- A de-modified system still listed as installed, with the removal visible only in a work order
- ICA and AFM supplements missing for modifications the aircraft demonstrably carries
What is at stake
An unsupported modification becomes a configuration question at transfer: the physical aircraft carries equipment the paper cannot explain, or claims equipment the cabin no longer has. Registry moves stall when an STC lacks an acceptable approval in the receiving jurisdiction, and missing ICA leave the next operator unable to maintain the installation legally.
Move from findings to resolution
Move from findings to a documented resolution path.
How the work runs
Sample the report
Select modifications by value, registry impact, and how heavily other reviews depend on their status.
Trace embodiment and approval
Find the accomplishment record, the approval basis, and the effectivity for each sampled change.
Verify the follow-ons
Locate AFM supplements, ICA, and weight and balance amendments the approvals require.
Publish the matrix
Deliver the claimed-versus-supported matrix with exceptions and registry-transfer notes.
What the buyer receives
- A claimed-versus-supported matrix across the sampled modifications
- Exception entries with document references for the diligence schedule
- A registry-transfer note flagging approvals that may not carry to the destination authority
Who uses the output
- Asset managers valuing modification content in the price
- Certification and registry advisors planning a jurisdiction transfer
- The receiving operator's engineering group preparing to maintain the installations
How the work fits into the transaction or program
Modification status feeds three neighboring reviews: the equipment list check, which confirms the hardware; the weight and balance review, which needs the amendments; and AD compliance, where method-of-compliance claims often rest on SB embodiment. Running them against a shared exception schedule keeps one configuration story across the deal.
Jurisdiction-specific considerations
An FAA STC does not automatically satisfy EASA, and the reverse also holds; bilateral agreements cover some approvals and leave others needing validation. Major repairs and alterations on US aircraft ride on FAA Form 337, a document class with no exact EASA twin, so aircraft with mixed histories need each change read in its original regime before judging transferability.
Regulatory limits
The review maps evidence to claims. It does not approve modifications, validate STCs across jurisdictions, issue or amend any certificate, or determine that the aircraft conforms to its type design; those judgments belong to the authorities and their designees.
What this review does not cover
- Physical inspection of installed modifications
- Obtaining STC validations or new approvals
- Redesign or engineering support for noncompliant installations
Specific to this review
- The complied column of a status report is the least trustworthy field in a data room because it collapses embodiment, approval, and effectivity into one unverifiable word.
- Cabin and connectivity modifications churn with each lessee, and their paper is the record class most likely to be stranded with a prior operator.
- A missing AFM supplement blocks operations in a way buyers underestimate: the next operator cannot legally fly the system it governs.
- De-modification records matter as much as embodiment records, since equipment removed without paper leaves the weight and balance and wiring records silently wrong.
Sources
U.S. Government (eCFR). Maintenance recordkeeping content and approval-for-return-to-service requirements, including 43.9, 43.11, and Appendix B.
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.
U.S. Government (eCFR). Records an owner or operator must keep, including total time in service, current status of life-limited parts, and AD compliance.
Frequently asked questions
Do FAA STCs carry over if we move the aircraft to an EASA registry?
Some do under bilateral arrangements, others need validation, and a few have no practical path. The review does not perform validations, but it flags which claimed approvals would face the question so registry planning starts from a real list instead of a surprise.
Relevant glossary terms
Related pages
Where this fits
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