Aircraft Maintenance Records Under Part-ML: What Owners Should Keep

Part-ML aircraft maintenance records are not one logbook and do not share one retention period. Treat them as a connected system: relevant aircraft, engine and propeller logbooks; current status; and detailed maintenance evidence.

Some records run until equivalent information supersedes them, some have a 36-month minimum, and others continue after permanent withdrawal. On sale, the records and retention clocks transfer.

This guide focuses on an owner within EASA Part-ML. Contracting a Continuing Airworthiness Management Organisation (CAMO) or Combined Airworthiness Organisation (CAO) changes management, not the need for intelligible history.

What counts as an aircraft maintenance record?

ML.A.305 of Regulation (EU) No 1321/2014 describes the aircraft continuing-airworthiness record system. It is broader than invoices and broader than a bound airframe logbook.

Separate three layers.

Aircraft, engine and propeller logbooks

Where applicable, these identify the long-running record streams for the aircraft and its serialized items. They connect utilisation and maintenance history to the correct aircraft, engine or propeller.

Current-status records

Current status answers “Where does the aircraft stand now?” Part-ML identifies records for matters including:

Airworthiness Directives (ADs) and measures mandated by the competent authority in immediate reaction to a safety problem;
modifications, repairs and other Design Approval Holder (DAH) maintenance recommendations;
the current mass-and-balance report;
compliance with the Aircraft Maintenance Programme (AMP);
life-limited and time-controlled components; and
outstanding deferred maintenance, including deferred defects.

They show what applies, what has been accomplished, what remains due and what is open. The aircraft Journey Log guide explains how flight-by-flight utilisation and observations feed the wider aircraft record.

The Certificate of Release to Service and detailed maintenance records

After maintenance, the applicable Certificate of Release to Service (CRS) and detailed records provide evidence of the work and its release. Supporting records may include work cards, maintenance data references, measurements, inspection results and component documents.

A CRS covers maintenance within its scope, not unrelated tasks, defects or components. Work cards without a clear release or aircraft identity do not establish current status.

Which records show the aircraft’s current status?

A current-status record should be concise and traceable. The owner should not need invoices to determine what is due.

AMP and scheduled-maintenance status

The current AMP identifies the maintenance basis. Its status should show scheduled tasks and the utilisation or calendar basis for the next due point. Flight time, cycles and calendar time are not interchangeable.

When the AMP changes, retain enough revision context to identify the programme that applied to earlier work.

AD status

The current AD status should identify applicable directives, actions and recurring requirements. “AD checked” is insufficient without the directive, method, evidence and any applicable next due point.

A Service Bulletin may be relevant to the evidence, but is not automatically an AD.

Life-limited and time-controlled components

Component status needs identity as well as numbers: part and serial number where applicable, limit, accumulated utilisation, its source and remaining or next-due position.

Totals must reconcile to installation and removal evidence, including when a component moves between aircraft.

Deferred maintenance

The current list covers outstanding deferred maintenance, including deferred defects. Link each item’s report, decision basis, conditions, original identification date and later evidence.

The aircraft defects under Part-ML article explains that lifecycle. It does not turn an administrative status into authority for further flight.

How long must Part-ML aircraft records be retained?

Retention follows the record’s purpose. “Keep everything for 36 months” is wrong because that minimum is only one part of ML.A.305.

The matrix summarizes ML.A.305 minimums. “Until superseded” requires newer equivalent information; an unsupported total is not equivalent.

Record type	What it establishes	Update trigger	Minimum retention under ML.A.305	Transfer with aircraft?	Source
Aircraft, engine and propeller logbooks, as applicable	The enduring record streams and identity context	Each relevant utilisation, maintenance or status event	Retain the required information within the periods applicable to the underlying record; do not treat the book itself as a 36-month disposable file	Yes, as part of the ML.A.305 records	ML.A.305(b), (h); ML.A.307(a)
Current AMP compliance status	Scheduled-maintenance position against the applicable programme	New accomplishment, utilisation or programme status	At least until the scheduled maintenance is superseded by scheduled maintenance of equivalent scope and detail	Yes	ML.A.305(d), (h)(4)
Current AD status	Applicability, action and recurring position	AD assessment, accomplishment or next-due change	At least 12 months after permanent withdrawal of the aircraft or component from service	Yes	ML.A.305(d), (h)(5)
Current modification and repair details	Aircraft configuration and approved change history	Embodiment or status correction	At least 12 months after permanent withdrawal of the aircraft, engine, propeller or other flight-safety-vital component from service	Yes	ML.A.305(d), (h)(6)
Other DAH maintenance recommendation status and current mass-and-balance report	Current recommendation and mass-and-balance context	Recommendation, embodiment or mass-and-balance change	ML.A.305(h) states no separate fixed period for these records; keep the required current status/report current	Yes	ML.A.305(d)(2), (5); ML.A.307(a)
Total time in service of the aircraft and all service-life-limited components	Hours, calendar time, cycles and landings, as applicable	Operation, installation or removal	At least 12 months after the aircraft or component has been permanently withdrawn from service	Yes; preserve component continuity	ML.A.305(h)(2)
Time in service since last scheduled maintenance of a service-life-limited component	Position since the most recent scheduled event	New scheduled accomplishment	Until superseded by scheduled maintenance of equivalent scope and detail	Yes	ML.A.305(h)(3)
Current list of deferred maintenance, including deferred defects	Which maintenance remains outstanding	Decision, condition change or completion	ML.A.305(h) states no separate fixed period for the list itself; keep the required current list current	Yes while part of the aircraft’s current record	ML.A.305(d)(6); AMC1 ML.A.403(d)
Detailed maintenance records for the aircraft and fitted service-life-limited components	What work was performed and the evidence supporting its scope	Completion and release of maintenance	Until superseded by information equivalent in scope and detail, but not less than 36 months after the aircraft or component was released to service	Yes	ML.A.305(h)(1); ML.A.307(a)

These are retention floors, not destruction dates. A superseded record may still support component history, a modification, a national requirement or a contract. Disposal should be documented.

What should the owner receive after maintenance?

The package depends on the work, but a receipt check asks:

Does the record identify the aircraft or component unambiguously?
What maintenance was performed, and what was not included?
Which approved or applicable maintenance data and revision were used?
Are measurements, inspections and replaced-component details captured where needed?
Is the CRS or other applicable release evidence present and attributable?
Which current-status records now need an update?
Does a removed or installed component bring records that must remain with it?

Under ML.A.305(a), enter the existing CRS as soon as possible and no later than 30 days after the maintenance task is completed. Entering it records the release; it does not give the owner authority to issue one. Paper left at the facility or a PDF held only in email is not a dependable owner record.

Can aircraft maintenance records be electronic?

AMC1 ML.A.305(a) and (e) says alternatives to a logbook or log card—such as paper, a spreadsheet or an IT system—can be acceptable. If IT is the only record system, it should have at least one regularly updated backup and safeguards against unauthorised alteration.

Practical owner controls include:

stable aircraft or component identity;
authoritative location and current version;
who changed the record and when;
corrections that leave the original clear;
appropriate access;
tested backup, recovery and export; and
links between status, CRS and detailed evidence.

ML.A.305(g) requires corrections to show the original entry clearly. Replacing a PDF or spreadsheet cell without history weakens trust. The index, recovery test and export steps above are practical advice.

A mixed system needs an index. Mark whether each item is an original, controlled electronic record or copy, and where the source can be retrieved.

What happens to the records when the aircraft is sold?

ML.A.307 requires the owner to ensure that the ML.A.305 continuing-airworthiness records are transferred to the new owner when the aircraft is permanently transferred. The applicable retention periods continue to apply to the new owner.

Inventory record classes, current and superseded items, and gaps. Export usable files and context; account access may disappear when permissions change.

Under ML.A.307(b), the owner must ensure that the records transfer to a contracted CAMO or CAO. Paragraph (c) continues the ML.A.305(h) retention periods for the new owner, CAMO or CAO. Make custody, return and export arrangements explicit.

What owner routine keeps the records usable?

A consistent routine prevents an annual reconstruction exercise.

When a maintenance package arrives

Check identity, scope and release evidence. File the package under the affected aircraft or component, then update the relevant AMP, AD, component, modification/repair or deferred-item status. Do not mark a broader case closed merely because one CRS was received.

Before annual review or transfer

Export an index and test retrieval. Sample current-status entries back to their sources. Check that aircraft and component histories can be transferred without losing their relationships.

If the aircraft is occasionally shared, give the co-owner appropriate access but keep one authoritative history. Administrative access does not confer PIC, continuing-airworthiness or certifying authority.

Part-ML maintenance records checklist

Use this as a records-control check:

aircraft, engine and propeller logbooks are identifiable and current where applicable;
total time, cycles and other source values use clear labels and units;
the current AMP compliance status is traceable to accomplishment evidence;
the current AD status identifies the directive, action and recurring position;
modifications, repairs and other DAH maintenance recommendations are current and traceable;
the current mass-and-balance report is identifiable;
life-limited and time-controlled components have identity and source history;
outstanding deferred maintenance, including deferred defects, is visible and linked to its report and decision;
each maintenance package includes the applicable release and detailed evidence;
corrections preserve the original entry;
retention is assigned by record class rather than one blanket period;
backups and exports have been tested; and
a transfer inventory can be produced without rebuilding the aircraft history.

Keep current status and supporting evidence connected. A tidy folder is not enough if it cannot explain configuration, utilisation, due position and open items; a spreadsheet is not enough if its evidence has disappeared.

Logga’s current product keeps private aircraft documents as versioned records with current and previous revisions, validity information and history. It does not determine maintenance completeness, calculate AD or AMP compliance, close defects or issue a CRS.

Contact Logga about setting up private, aircraft-specific document records and controlled revision history for your aircraft.