Modification and STC status
Boeing 737 MAX modification and STC status records review
A Boeing 737 MAX modification-status review confirms the changes the records claim are embodied match what is approved and recorded against the correct effectivity. It is run by or for a party evaluating, transferring, or maintaining a specific tail. Service bulletin embodiment, STC files, configuration lists, and the approval data behind each change are reconciled so a modification is neither claimed without a basis nor recorded against a serial number it does not apply to. You receive a supported exception list of unsupported or mis-recorded changes, a source map to the approval evidence, and a plan to close each open item.
When this review is needed
- A buyer needs the embodied modification list confirmed before pricing, because an unsupported STC can force removal after purchase.
- Service bulletin embodiment is claimed at a revision the file does not actually support.
- A cabin or avionics STC was installed under a prior operator and its approval basis has never been checked against this register.
- The modification status report and the configuration list disagree and the difference has to be resolved.
The problem
Modification status drifts as service bulletins, STCs, and equipment changes accumulate across operators, and the report that summarizes them lags the actual embodiment. A bulletin can be recorded at the wrong revision, an STC can carry approval data valid on one register but not the receiving one, and a change embodied on the airframe can sit in the report without the substantiation behind it. On the MAX, where avionics and software modifications are frequent and part-number driven, a mis-recorded change is easy to miss until a transaction forces the check.
What gets reviewed
- Embodied service bulletins reconciled to the recorded revision and effectivity for this serial number
- STC files matched to approval data valid for the aircraft and its register
- Configuration lists reconciled against the modification status report
- Approval and substantiation data confirmed present for each embodied change
- Avionics and software modifications checked against the recorded part-number configuration
- Changes claimed on the airframe but absent from the report identified and flagged
Scope this review
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What gets validated
- Each embodied service bulletin carries the correct revision and applies to this effectivity
- Every claimed STC has approval data appropriate to the installation and the register
- The configuration list and the modification report describe the same airframe
- Substantiation data exists for changes that altered structure, systems, or software
- Equipment changes recorded as routine are checked to confirm they did not require modification treatment
Evidence normally required
- The modification status report and the configuration list
- STC files with their approval and substantiation data
- Service bulletin embodiment records with revision and effectivity
- The delivery configuration baseline for the serial number
- Any prior operator's modification records for changes embodied off-register
Common discrepancies
- A service bulletin recorded at a revision the embodiment evidence does not support
- An STC with approval data valid on the prior register but not the current one
- A change embodied on the airframe that never made it into the modification report
- A configuration list that lags a modification the report already shows as done
What is at stake
A modification claimed without traceable approval data may have to be removed or re-substantiated, which costs far more than confirming the basis up front. An STC accepted on the wrong register can stall an export or an induction, and a configuration list that disagrees with the modification report undermines every downstream status that assumes the airframe is in the recorded state.
Move from findings to resolution
Move from findings to a documented resolution path.
How the work runs
Assemble the claimed status
Pull the modification report, STC files, and service bulletin embodiment for the serial number.
Check effectivity and basis
Confirm each change applies to this airframe and carries approval data valid for its register.
Reconcile to configuration
Match the modification report against the configuration list at the part-number level.
Flag the exceptions
List unsupported, mis-recorded, or unrecorded changes with the evidence or decision each needs.
What the buyer receives
- A supported exception list of unsupported, mis-recorded, or unrecorded modifications
- A source map linking each embodied change to its approval and substantiation data
- A closure plan for the modifications that need evidence, re-substantiation, or a decision
Who uses the output
- Records teams setting a modification baseline the rest of the file can rest on
- Engineering deciding how to treat a change with no traceable approval basis
- Asset and acquisition teams pricing the configuration the records actually support
How the work fits into the transaction or program
The modification review establishes the configuration state that AD applicability, weight and balance, and equipment status all depend on. It runs before a transaction or after a heavy check so the records catch up to the airframe, and its exception list drives remediation or an engineering decision before anything else is built on the baseline.
Aircraft-specific considerations
The 737 MAX places heavy weight on configuration control, software load status, and avionics part numbers, so a modification review on this family spends more time on data-loadable content and STC-driven avionics changes than it would on an older narrowbody. A change embodied under a prior operator has to be reconciled to the delivery-to-operator baseline so the current report reflects the airframe as it actually stands.
Jurisdiction-specific considerations
An STC approved by the FAA is not automatically accepted by EASA and the reverse holds too, so the review flags each modification whose approval basis is register-specific and notes what a transfer between the two systems would require rather than treating the embodiment as portable.
Regulatory limits
The review confirms the recorded modification status is internally consistent and supported by approval data. It does not approve a modification, grant or validate an STC, or determine that the aircraft is in an airworthy configuration.
What this review does not cover
- Developing or approving new modification or STC data
- Physical configuration survey of the aircraft
- Any airworthiness determination on the installed modifications
Specific to this review
- Effectivity is where modification records break most often: a bulletin can be genuinely embodied but recorded against a serial it does not apply to.
- On the MAX a software or avionics modification is part-number driven, so the modification report and the recorded configuration have to agree at the part-number level, not just the bulletin level.
- An STC valid on the register it was approved for can stall an export or induction on another, so register-specific approvals are flagged before a transfer, not after.
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
What happens to a modification with no approval data on file?
It is flagged as unsupported and carried as an exception with the options set out: recover the substantiation, re-substantiate to an acceptable basis, or remove the change. Deciding among those is an engineering call, but the review makes the exposure explicit so it is priced or closed rather than discovered later.
Relevant glossary terms
Related pages
Where this fits
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