Deferred maintenance
Airbus A350 family deferred maintenance records review
This review reconciles the deferred maintenance carried on an Airbus A350 family aircraft, confirming each open item is within its allowable interval and each cleared item has a real corrective action behind it. It is run by or for a lessor, operator, or manager who needs an honest picture of what is deferred and whether the deferral basis holds. It reads the deferred maintenance log against the MEL and CDL that authorize each item, checks category time limits, and confirms clearing entries actually closed the defect they cite. You receive an exception list of items out of limit or cleared without evidence, a source map to the authorizing reference behind each, and a plan to resolve the open position.
When this review is needed
- A serial number is being handed over and the open deferral position has to be settled before acceptance.
- The deferred maintenance log shows items whose category time limit may have run.
- A cleared deferral cites a corrective action that is not in the file.
- A buyer needs the carried-forward defect list understood before it relies on the aircraft's status.
The problem
Deferred maintenance is where an aircraft's real condition can hide behind an orderly log. Each open item is only acceptable while it stays inside its MEL or CDL category interval, and on a long-haul aircraft that flies daily those intervals move fast. A deferral cleared on the log may cite a corrective action that never made it into the records, or an item may sit open past the category limit that authorized deferring it. The log looks controlled while the position underneath it drifts out of tolerance.
What gets reviewed
- Every open deferral matched to the MEL or CDL item that authorizes it
- Category time limits checked against each open item's deferral date and the aircraft's utilization
- Clearing entries confirmed to cite a corrective action recorded in the file
- Repetitive or rolling deferrals examined for a valid basis rather than repeated re-deferral
- Interaction between open deferrals checked where two items affect the same system
- Out-of-limit or unsupported items carried onto an exception list with the evidence or action owed
Scope this review
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What gets validated
- Each open deferral references a specific MEL or CDL item that permits deferring it
- No open item sits past the category time limit its authorizing reference allows
- A cleared deferral is supported by a corrective-action entry that closes the cited defect
- A rolling deferral has a basis for continued deferral rather than a silent re-clock
- Two deferrals affecting one system are assessed together rather than in isolation
Evidence normally required
- The deferred maintenance log or carried-forward defect list
- The MEL and CDL applicable to the aircraft
- Corrective-action records cited by cleared deferrals
- Current utilization to test category time limits
- Technical-log entries recording the original deferrals
Common discrepancies
- An open deferral carried past the category time limit that authorized it
- A cleared item citing a corrective action absent from the records
- A rolling deferral re-clocked repeatedly with no valid basis for continued deferral
- Two open deferrals on one system with no combined assessment
What is at stake
An item carried past its allowable interval is a defect that was deferred without a valid basis, and that is exactly what an auditor or a receiving operator looks for. A cleared deferral with no corrective action in the file is a defect that may still be present. Either weakens acceptance, and on a handover the open deferral position is often a direct negotiation point, so an unreconciled log costs leverage as well as time.
Move from findings to resolution
Move from findings to a documented resolution path.
How the work runs
Read the log against MEL and CDL
Match each deferral to the reference that authorizes it and record the deferral date.
Test the time limits
Check each open item against its category interval and the aircraft's utilization since deferral.
Confirm the clearings
Verify each cleared item cites a corrective action that is actually in the records.
List the open position
Flag out-of-limit and unsupported items and set the plan to close each.
What the buyer receives
- An exception list of deferrals out of limit or cleared without supporting evidence
- A source map from each deferral to its MEL or CDL basis and clearing action
- A plan to close, clear, or re-substantiate each open item
Who uses the output
- Records teams settling the open deferral position before handover
- Continuing-airworthiness staff confirming each open item still holds a valid basis
- Diligence and asset teams pricing the carried-forward defect exposure
How the work fits into the transaction or program
The deferred maintenance position is one of the last things settled before a handover, because it moves right up to the acceptance date. This review reconciles the log to its MEL and CDL basis and to the clearing evidence, then feeds the open position into the redelivery discussion where deferrals are negotiated. Its exception list drives clearing or re-substantiation while the aircraft is still under the outgoing operator's control.
Aircraft-specific considerations
The A350's daily long-haul utilization consumes calendar and cycle allowances on deferred items quickly, so a category interval that looked comfortable at deferral can lapse within weeks. The aircraft's electronic technical log means deferrals and their clearing often live in a digital stream that has to be exported and reconciled rather than read from a paper log, and the high systems integration means two deferrals can interact through shared avionics in ways a line-by-line read would miss.
Regulatory limits
The review reconciles the deferred maintenance records and reports where an item is out of limit or cleared without evidence. It does not clear a defect, grant an MEL or CDL relief, or determine that the aircraft is airworthy with its deferrals open; those rest with the operator and the authority.
What this review does not cover
- Performing the corrective action that would clear a deferral
- Granting or interpreting MEL or CDL relief on the operator's behalf
- Any airworthiness determination on the aircraft's deferred position
Specific to this review
- A deferral is only acceptable inside its category time limit, and daily long-haul flying can run that limit out faster than a paper log makes obvious.
- A cleared deferral citing a corrective action that is not in the file may be a defect that was never actually fixed.
- Rolling re-deferral without a fresh basis is a frequent finding, because re-clocking an item is easier than closing it.
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 do deferrals need reviewing if the log shows them as controlled?
A deferral is only valid while it stays inside the MEL or CDL category interval that authorized it, and on a daily long-haul aircraft that interval can lapse quickly. The review tests each open item against its time limit and confirms every cleared item cites a corrective action that is really in the file, so an item that looks controlled but has run out of limit or was never actually fixed shows up as an exception.
Relevant glossary terms
Related pages
Where this fits
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