GTF deferred maintenance
Geared turbofan engine deferred-maintenance records review
This review confirms that the deferred maintenance carried on a geared turbofan engine installation was deferred on a valid basis and cleared within its limits. It is run when a GTF asset is being evaluated, transferred, or held and its deferral history has to be trusted. It checks deferment entries, MEL and CDL references, corrective actions, and the clearing entries that close each item against the deferred maintenance log. You receive an exception list of deferrals lacking a valid basis or a clearance, a source map per item, and a closure plan for the serial number.
When this review is needed
- The deferred log shows items open and their deferral limits have to be checked against the calendar.
- A deferment cites an MEL item and the reference and category have to be confirmed.
- A cleared item on the log has no corrective action or clearing entry behind it.
- A GTF asset is transferring and the buyer wants the open and cleared deferrals reconciled.
The problem
Deferred maintenance is a moving target. An item is deferred against an MEL or CDL provision, carried under a repair interval, and cleared with a corrective action, but the log tracks the status while the basis lives elsewhere. A deferment can cite an MEL category the item does not qualify for, a repair interval can lapse without anyone clearing or re-deferring it, and a cleared item can lack the corrective action that closes it. The log looks orderly right up until the deferrals are reconciled to their references.
What gets reviewed
- Each open deferral checked against its repair interval and the current calendar
- MEL and CDL references confirmed for category and applicability
- Corrective actions present for items the log shows cleared
- Clearing entries closing each deferral with the evidence behind them
- The deferred log reconciled to the logbook for the same items
- Lapsed or unsupported deferrals carried as tracked exceptions
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
- Each open deferral is within its repair interval or has been re-deferred on a valid basis
- MEL and CDL references cite a provision the deferred item actually qualifies under
- Every item shown cleared has a corrective action and a clearing entry behind it
- The deferred log status agrees with the logbook for the same items
- No deferral has lapsed past its interval without a clearance or re-deferment recorded
Evidence normally required
- The deferred maintenance log for the installation
- The applicable MEL and CDL for the aircraft
- Deferment entries with their references and intervals
- Corrective-action and clearing records for cleared items
- Logbook entries covering the deferrals for reconciliation
Common discrepancies
- A deferral carried past its repair interval with no clearance or re-deferment
- An MEL reference citing a category the deferred item does not qualify under
- A cleared log item with no corrective action behind it
- A deferred log status that disagrees with the logbook for the same item
What is at stake
A deferral carried past its repair interval is a compliance exposure the operator holds without knowing it, and a cleared item with no corrective action is an open defect hiding as a closed one. At a transaction or surveillance, an unsupported deferral is a direct finding, and a lapsed interval can question the aircraft's dispatch status for the period it was carried.
Move from findings to resolution
Move from findings to a documented resolution path.
How the work runs
Pull the log
List every open and cleared deferral with its reference, interval, and status.
Test the basis
Confirm each deferral cites a valid MEL or CDL provision and sits within its interval.
Verify the clearances
Check that cleared items carry a corrective action and a clearing entry.
Reconcile and list
Compare the log to the logbook and record the lapsed or unsupported deferrals.
What the buyer receives
- An exception list of deferrals lacking a valid basis, a clearance, or an in-limit interval
- A source map linking each deferral to its reference, action, and clearing entry
- A closure plan for the unsupported deferrals on the serial number
Who uses the output
- Records teams reconciling the open and cleared deferrals against their references
- Continuing-airworthiness teams confirming no deferral has lapsed its interval
- Asset managers weighing the exposure the open deferrals carry into a transaction
How the work fits into the transaction or program
Deferred maintenance connects the non-routine defects that were carried rather than cleared to the logbook that records their status. The review reconciles the two, and any deferral that turns out to be a live defect feeds back into the non-routine closure the engine also depends on.
Aircraft-specific considerations
A geared turbofan installation accrues deferrals across a busy in-service life, and the pressure to keep aircraft flying means items are deferred quickly and cleared later. The review checks each deferral against its interval and MEL basis, because a high deferral turnover on this type makes a lapsed interval or a mis-categorized MEL reference a realistic finding rather than a rarity.
Jurisdiction-specific considerations
MEL structure and deferral conventions differ between FAA and EASA operations, so a deferral valid under one operator's MEL may not map cleanly onto a receiving operator's MEL in the other system. The review notes where a carried deferral will need re-basing to the receiving operator's MEL.
Regulatory limits
The review reconciles the deferred maintenance records to their references and clearances. It does not defer or clear an item, approve an MEL provision, or determine that the aircraft's dispatch status is airworthy.
What this review does not cover
- Deferring, clearing, or re-categorizing any maintenance item
- Approving or amending the MEL or CDL
- Any airworthiness or dispatch determination on the aircraft
Specific to this review
- A deferral log records status, not basis, so an item can read as validly deferred while its MEL category does not actually cover it.
- A cleared item with no corrective action is an open defect disguised as a closed one, which is why clearing entries are checked individually.
- High deferral turnover on a busy installation makes a lapsed repair interval a common finding, so intervals are tested against the calendar item by item.
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
What is the risk in a deferral that shows cleared on the log?
A cleared status only means someone marked it closed. If no corrective action and clearing entry sit behind it, the underlying defect may still be live, carried as if resolved. The review tests each clearance against its evidence so a closed status reflects work that was actually done rather than a log entry alone.
Relevant glossary terms
Related pages
Where this fits
Talk to an engineer who has done this work
We will walk through your current state, the records or evidence involved, and a scoped first engagement.
Talk through the aircraft, records, evidence, deadline, and next useful step.