Modification status
Airbus A350 family modification and STC status records review
This review verifies the modification and STC standing recorded for an Airbus A350 family aircraft against the approval data and effectivity that should support each change. It is run by or for a lessor, operator, or manager who needs the recorded configuration to reflect changes that are real, approved, and applicable to this serial number. It examines Service Bulletin embodiment, STC files, and the configuration list, confirming each modification carries an approval basis and is booked against effectivity that matches the airframe. You receive an exception list of modifications that lack support or sit against the wrong effectivity, a source map to the approval behind each one, and a plan to resolve the open items.
When this review is needed
- Modification history has built up across operators and no one has reconciled the STC files to approval data recently.
- A cabin or avionics change is claimed on the configuration list but its STC package is not in the file.
- A Service Bulletin shows as embodied without the revision and effectivity that make it applicable here.
- A buyer needs the modification standing confirmed before it prices the configuration.
The problem
Modification status drifts because each change is small, the approval package lives apart from the configuration list, and the list is easy to update without the evidence catching up. On an A350 the density of cabin, connectivity, and avionics modifications makes this worse: an STC embodied under one authority may need a validating approval to stand under another, and a Service Bulletin can be booked as embodied against a revision or effectivity that does not actually apply to the serial number. The configuration list then reads clean while the basis underneath it is thin.
What gets reviewed
- Service Bulletin embodiment recorded against the correct revision and effectivity for the serial number
- STC files present with the approval and the installation records that put each STC on this aircraft
- Configuration list reconciled to the modifications the approval evidence actually supports
- Cross-authority validity of STCs where the aircraft is registered or moving under FAA and EASA
- Approval basis and substantiation data identified for each embodied change
- Unsupported or mis-effectivity modifications carried onto an exception list with the evidence owed
Scope this review
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What gets validated
- Each embodied Service Bulletin cites the revision and effectivity that apply to this serial number
- Every STC on the configuration list has an approval and an installation record putting it on the aircraft
- An STC relied on under a second authority carries the validating approval that authority requires
- The configuration list contains no modification that the approval evidence cannot substantiate
- Effectivity booked against a change matches the airframe history rather than a fleet default
Evidence normally required
- The modification and STC status report or configuration list
- STC certificates and their installation and approval packages
- Service Bulletin embodiment records with revisions
- Approval and substantiation data for the embodied changes
- The register and jurisdiction the aircraft operates or is moving under
Common discrepancies
- An STC on the configuration list with no approval package behind it
- A Service Bulletin marked embodied against a revision that does not apply to this serial number
- A modification approved under one authority with no validating approval for the receiving register
- A configuration entry booked against effectivity that the airframe history does not support
What is at stake
A modification recorded without traceable approval data can force removal or re-substantiation, and either is far more expensive than confirming the basis before it is relied on. An STC that stood under one authority but was never validated for the register the aircraft is moving to stalls acceptance until the approval is reconstructed. A buyer who finds an unsupported change on the configuration list discounts the whole configuration, not just the single line.
Move from findings to resolution
Move from findings to a documented resolution path.
How the work runs
Assemble the claimed configuration
Pull the modification and STC status the records assert for the serial number.
Check basis and effectivity
Confirm each change carries approval data and is booked against effectivity the airframe supports.
Test cross-authority validity
Verify that STCs relied on under a second authority carry the validating approval it requires.
List the exceptions
Flag unsupported or mis-effectivity modifications with the approval each still needs.
What the buyer receives
- An exception list of modifications lacking approval data or sitting on the wrong effectivity
- A source map tying each contested change to the approval and installation record behind it
- A resolution plan naming the approval owed to clear each open modification
Who uses the output
- Records teams setting a modification baseline the rest of the file relies on
- Engineering deciding how to treat a change with no traceable approval basis
- Asset and acquisition teams pricing the configuration the evidence actually supports
How the work fits into the transaction or program
Modification status underpins AD applicability, equipment standing, and any later change tracking, so this review runs before a transaction or right after a modification campaign. Its exception list drives remediation while the approval holders and installing organizations are still reachable, and the reconciled modification baseline then supports the configuration and equipment reviews built on top of it.
Aircraft-specific considerations
The A350 carries a heavy load of cabin, in-flight-connectivity, and avionics modifications, and its software-defined configuration means an STC can bundle a data or software change that has to be traced alongside the hardware. Long-haul cabin reconfigurations recur across a lease life, so the same seat or monument zone can hold several superseding STCs whose effectivity and approval have to be untangled in order.
Regulatory limits
The review confirms that recorded modifications are supported by approval data and booked against correct effectivity. It does not approve a modification, grant or validate an STC, or determine that the installed configuration is airworthy; those actions rest with the applicant and the authority.
What this review does not cover
- Developing or approving new modification or STC data
- A physical configuration survey of the installed modifications
- Any airworthiness determination on the modified configuration
Specific to this review
- Cross-authority validity is a frequent A350 trap: an STC good under one authority may need a separate validation to stand on the receiving register.
- Effectivity is where modification records break most often, because a change can be genuine yet booked against a serial number it does not apply to.
- A software or data element bundled into a modification has to trace alongside the hardware, or the change is only half supported.
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
An STC was approved when it was installed. Why check it again?
An STC approved under one authority does not automatically stand under another. If the aircraft operates or is moving to a register governed by a different authority, that STC may need a validating approval to remain relied on. The review confirms each STC carries the approval the current or receiving jurisdiction actually requires.
Relevant glossary terms
Related pages
Where this fits
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