Deferred maintenance history review for lease transitions

When this review is needed

• Return conditions require zero open deferrals at redelivery and the log's open count keeps changing depending on who compiles it.
• Clearance entries in the log cite work orders that nobody has located in the transition folders.
• The same defect appears deferred repeatedly under different item numbers and the counterparty has started asking why.
• A mid-term operator change means the deferral history spans two MEL approvals and two sets of procedures.

The problem

Deferral logs are shift documents. Entries get opened by one crew under dispatch pressure and closed by another weeks later, with the clearance line written after the urgency has passed. Across a lease term that produces a history where the log, the status summaries, and the work-order archive each tell a slightly different story. At redelivery the return conditions usually demand a clean position, so every ambiguous line turns into a negotiation the transition team has to win with evidence it may not have gathered yet.

What gets reviewed

• The deferral log across the full lease term, matched to the MEL and CDL authorizations in force
• Rectification-interval compliance and any extensions, with the approval trail for each extension
• Corrective-action records behind every cleared deferral
• Open deferrals at the transition date measured against the return-condition requirements
• Deferral-related entries in acceptance notes and the open-item tracker
• Recurring deferrals of the same defect that may signal an underlying unresolved problem

What gets validated

• Each deferral cites an MEL or CDL item, or another authorized basis, that covers the defect as described
• Rectification intervals were respected or extended through the operator's approved process
• Every closure entry links to a work order, task card, or logbook action present in the file
• Parts replaced during clearance carry their release documentation
• The open-deferral count at handover matches across the log, the tracker, and the status summaries

Evidence normally required

• The deferred maintenance log or deferred-defect listing for the lease term
• The approved MEL and CDL applicable during the period
• Work orders, task cards, and logbook entries cited by clearance actions
• Return-condition provisions covering deferred and open items
• Transition correspondence and the current open-item tracker

Common discrepancies

• Clearance entries referencing work orders absent from every folder in the file
• Deferral extensions recorded without the approval the operator's procedure requires
• One defect deferred repeatedly under fresh item numbers, obscuring how long it was actually open
• An open-item count that differs between the deferral log and the summary handed to the counterparty

What is at stake

An open deferral at redelivery blocks acceptance under most leases until it is physically cleared, on a timeline the check schedule never allowed for. A cleared deferral without corrective-action evidence invites the counterparty to treat it as open anyway. If the file travels through a registry change, an examiner reading repeated extensions without recorded approvals will ask questions that reach well past the deferral log itself.

How the work runs

What the buyer receives

• A line-item exception list separating unsupported closures from genuinely open items
• A reconciled open-deferral position as of the transition date
• Source citations for every supported closure, ready for counterparty review
• Draft tracker language for each item still needing evidence or physical action

Who uses the output

• Transition leads who must show a clean deferral position before acceptance
• Maintenance control planning the physical clearance of items that really are open
• Lessor technical teams sorting records gaps from unfinished maintenance

How the work fits into the transaction or program

Deferral evidence sits between the maintenance-status story and the airworthiness review records, and discrepancies here tend to surface in both. Genuinely open items route to maintenance planning for physical action; unsupported closures route to records retrieval, sometimes reopening work that was invoiced and forgotten years earlier. The reconciled open position becomes the number the redelivery meeting works from.

Jurisdiction-specific considerations

ICAO Annex 6 sets the baseline expectation that deferred defects are controlled, while FAA operators defer against an approved MEL under their operations specifications with category A through D rectification intervals, and EASA operators run an equivalent scheme under their approvals with CAMO oversight per Regulation (EU) No 1321/2014. MEL approvals belong to the operator, so a mid-term operator change splits the history into two regimes that the review has to read separately.

Regulatory limits

Nothing in this review authorizes, extends, or clears a deferral, and it makes no judgment about dispatchability or airworthiness. MEL decisions and defect rectification remain with the operator, its maintenance organizations, and its authority.

What this review does not cover

• Performing or certifying corrective maintenance
• MEL interpretation or dispatch decisions
• Negotiating which open items the counterparty must accept

Specific to this review

• Clearance entries are routinely the weakest record in the deferral chain, because the operational pressure that created the paper trail ends the moment the defect does.
• Return conditions demanding zero open deferrals convert every unsupported closure into a potential open item in the counterparty's reading, which is why closure evidence matters as much as the closure itself.
• A defect cycling through repeated deferrals under new item numbers tells an incoming operator more about the aircraft's condition than the status summary does, and experienced reviewers hunt for the pattern.
• Extension approvals are operator-procedure documents that rarely transfer with the aircraft unless someone pulls them deliberately during the transition.

Sources

Frequently asked questions

Relevant glossary terms

Related pages

Where this fits