Mod and STC status
Modification and STC status reviewed from engine-module sources
This review tests the modification status report against the engine-module file that should substantiate it. Records leads, CAMO engineers, and lessor technical teams use it when mod status will be relied on at transfer, at redelivery, or in setting the configuration baseline for the next operator. Each SB, modification, and STC shown embodied is traced to effectivity for the serial number, embodiment evidence in the build or visit records, and the resulting part-number changes. Lines the file cannot substantiate are returned as configuration exceptions.
When this review is needed
- A configuration-dependent AD needs the mod status settled before its applicability call can be defended.
- The status report was inherited as a fleet-level export and this serial number's actual state is uncertain.
- An engine is being marketed and its value case rests partly on claimed SB incorporation.
- Post-visit records show part-number changes that the status report has not caught up with.
The problem
Mod status reports are frequently maintained at fleet level and copied forward at each transfer, while embodiment happens engine by engine at shop visits. The two drift apart. A bulletin shown incorporated may have been done on sister engines only, and a bulletin done at the last visit may be missing from the report entirely, with the truth sitting unread in build sheets and part-change records.
What gets reviewed
- Each status line resolved to effectivity for this engine serial number, never the fleet
- Embodiment claims traced to visit records, task cards, or build sheets naming the work
- Pre-mod and post-mod part numbers verified against fitted hardware in the build and release records
- STCs checked for installation evidence and the approval reference carried in the file
- Superseded or partially embodied bulletins identified and their actual state recorded
- Interaction with AD applicability noted where a mod is the terminating or triggering action
Scope this review
Tell us the asset, the event, and the evidence in scope, and we will outline a focused first engagement.
Send a representative, redacted record set and we will scope the review.
What gets validated
- No line claims embodiment without a dated record of the work on this serial number
- Post-mod part numbers on the status agree with the hardware the build sheets show installed
- STC references resolve to the approval and to installation records, both
- Bulletins marked not applicable carry an effectivity basis, never a bare annotation
- Partial embodiments state which portion was done and what remains open
Evidence normally required
Common discrepancies
- Embodiment inherited from a fleet report with no work record for this serial number
- A bulletin actually done at the last visit, visible in build sheets, missing from the status entirely
- Post-mod part numbers on the status while pre-mod hardware remains fitted per the release records
- STC lines carrying the approval reference but no evidence the installation ever occurred
What is at stake
Configuration claims that fail under scrutiny undermine the file beyond the single line: AD applicability built on a phantom mod becomes a compliance question, and a buyer who catches one unsupported bulletin will re-verify everything at the seller's expense. Corrective embodiment evidence gets harder to obtain each year after the shop visit that would have produced it.
How the work runs
Resolve effectivity
Confirm each status line actually applies to this serial number at its build standard.
Chase embodiment evidence
Locate the dated work record behind every claimed incorporation.
Reconcile the hardware
Compare pre-mod and post-mod part numbers against build and release records.
State the configuration
Issue the substantiated status with exceptions and a corrected draft.
What the buyer receives
- A substantiated configuration statement, line by line, for the engine as evidenced
- Configuration exceptions for the trace file with the missing evidence named
- A corrected-status draft the records owner can adopt after exceptions resolve
Who uses the output
How the work fits into the transaction or program
Modification status is the configuration authority that the equipment list, weight and balance amendments, and several AD determinations depend on. This review draws on the shop-visit and build-sheet evidence verified upstream and hands a settled configuration picture to the reviews downstream of it.
Start with a single asset
Confirm release certificates and component traceability are complete.
Jurisdiction-specific considerations
FAA-side embodiment rides on 14 CFR Parts 21 and 43, with AC 21-40 relevant to STC-related documentation; EASA-side design changes trace through Regulation 748/2012 and their incorporation through 1321/2014 records. The same physical modification can be covered by an STC on one registry and a different approval instrument on the other, so cross-registry engines need each claim tied to the instrument valid for the current registration.
Regulatory limits
The review substantiates what the records show embodied. It does not approve modifications, extend or transfer design approvals, or decide AD compliance; it supplies the evidenced configuration on which the responsible engineers make those determinations.
What this review does not cover
- Physical configuration inspection of the engine
- Obtaining new or replacement design approvals
- AD compliance determinations themselves
Specific to this review
- Fleet-level status reports are the single most common origin of phantom embodiments on individual engines.
- Part-number evidence outranks status annotations: hardware recorded fitted at release is the fact the rest must reconcile to.
- Terminating-action bulletins deserve first attention, since an unsupported one silently reopens a closed AD.
- Partially embodied bulletins hide in binary status columns that only offer done or not done.
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
Why does one unsupported SB line matter if the engine flies fine?
Because status lines are load-bearing for other determinations. AD applicability, equipment-list accuracy, and purchase-price assumptions all cite mod status as fact. One line shown wrong converts the report from evidence into a claim, and every downstream user starts re-verifying at your cost.
Relevant glossary terms
Related pages
Where this fits
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