Deferrals and closures
Deferred maintenance history in the shop-visit source file
Deferrals opened before or during a shop visit are supposed to leave the visit either closed with evidence or carried forward under control. This review reads the deferred maintenance log against the work orders, corrective-action cards, and test data in the source file to prove which of the two happened for every line. It runs at closeout for the quality manager or the accepting lessor. Deferrals shown closed without corrective evidence, and open deferrals missing their control basis, come back as itemized exceptions.
When this review is needed
- Defects deferred into the visit were supposed to be worked and the log now shows them cleared.
- MEL items were carried through the visit and their rectification intervals need a defensible restart or closure.
- The operator's CAMO must account for every open deferral before the aircraft rejoins the program.
- Acceptance terms bar carry-forward defects and the log must prove a clean handback.
The problem
A deferral log tracks two different truths at once: what was wrong, and what was done about it. Shops close deferrals administratively when the related card is stamped, but the card sometimes records an inspection, an access, or a partial fix rather than the corrective action the deferral called for. Reading the log alone, everything looks closed. Reading the cards behind it takes hours per aircraft, so at closeout the gap between the log and the evidence goes unmeasured.
What gets reviewed
- Every line of the deferral log traced to its originating defect report
- Closures matched to corrective-action cards, replaced-part releases, and test data
- Open deferrals checked for a current control: MEL category, interval, and authorization
- Deferral extensions verified against the approval authority that granted them
- Interval arithmetic checked from the deferral date, category, and any extension
- Transfers between tracking systems during the visit reconciled so no line was dropped
Scope this review
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What gets validated
- Each closed deferral cites a card whose work actually rectifies the recorded defect
- Parts changed to clear a deferral carry release certificates in the file
- Functional or operational test evidence exists where the corrective action required it
- Every open deferral carries an unexpired interval computed from a documented start point
- No defect report in the file lacks a corresponding deferral or closure line
Evidence normally required
- The deferred maintenance log covering the visit period
- Defect reports and originating pilot or maintenance entries
- Corrective-action cards, work orders, and test records
- MEL references and any deferral extension approvals
- Release certificates for parts installed against deferrals
Common discrepancies
- Deferrals closed against cards that record access or inspection but no rectification
- An extension applied without the approval record the MEL preamble requires
- Interval start dates reset at closeout with no basis in the corrective action
- Lines dropped when the log migrated between the operator's and the shop's tracking systems
What is at stake
A deferral closed without corrective evidence resurfaces as an open defect with a broken history, and the interval clock behind it becomes unverifiable. For MEL-controlled items that can mean an item flew beyond its category limit on paper, a finding regulators treat seriously regardless of the aircraft's actual condition. At lease return, carried defects that were thought closed become last-minute commercial disputes with no time left to gather the missing cards.
How the work runs
Rebuild the population
Merge the induction log, shop tracking, and closeout log into one deferral population with no dropped lines.
Test every closure
Read each closing card and confirm the work rectifies the recorded defect, with parts and tests evidenced.
Control every open line
Verify category, interval, start point, and any extension for deferrals leaving the visit open.
Hand over the register
Deliver the verified carry-forward register and the exception list for acceptance.
What the buyer receives
- An exception list splitting false closures from uncontrolled open deferrals
- A verified carry-forward register the CAMO can adopt at program re-entry
- Document requests for the specific cards or tests each false closure needs
Who uses the output
- Quality managers deciding what the closeout signature actually attests to
- CAMO staff re-baselining deferral control as the aircraft returns to service
- Asset managers enforcing handback conditions on carried defects
How the work fits into the transaction or program
Deferral control passes through more hands at a shop visit than any other record: operator to shop at induction, between shop systems during the visit, and back again at closeout. This review audits those handoffs at the last point where the shop can still produce the missing card, and it gives the CAMO a deferral register it can trust on day one back in service.
Start with a single asset
Confirm release certificates and component traceability are complete.
Jurisdiction-specific considerations
ICAO Annex 6 frames deferred defects as a continuing-airworthiness control, which FAA and EASA implement differently: 91.417 keeps the defect record with the operator, while EU 1321/2014 makes the CAMO accountable for deferral management and review. Where a visit spans regimes, the review notes which authority's deferral rules governed each line.
Regulatory limits
The review establishes what the file evidences about each deferral. It does not authorize deferrals or extensions, restart intervals, judge MEL applicability, or clear defects; those decisions stay with the operator, the CAMO, and the certifying staff.
What this review does not cover
- Rectification of defects or performance of test flights
- MEL revision or categorization decisions
- Ongoing deferral tracking after the acceptance date
Specific to this review
- The most damaging finding class is the administrative closure: a stamped card that fixed nothing, closing a deferral that silently persists.
- Interval arithmetic fails most often at extensions, because the extension record lives in a different system than the log.
- System migrations during a visit are where whole deferral lines vanish; reconciling the induction log against the closeout log is the only test that catches it.
- A deferral carried through a heavy check draws attention in any later audit, because reviewers expect heavy-check access to have enabled the fix.
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). Records an owner or operator must keep, including total time in service, current status of life-limited parts, and AD compliance.
European Union / EASA. Continuing airworthiness, maintenance records, CAMO responsibilities, and the airworthiness review process in the EASA system.
International Civil Aviation Organization. International standards for aircraft operation, including maintenance program and recordkeeping expectations.
Frequently asked questions
Why review deferrals at closeout instead of at the next records audit?
Because the closing evidence is a shop card, and shops archive or disperse cards quickly after delivery. At closeout the missing card is a walk to the records office; a year later it is a formal request to an archive that may not have it.
Relevant glossary terms
Related pages
Where this fits
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