The CAMO Role in Service Bulletin and Airworthiness Directive Management

In the UK and EASA regulatory systems, the Continuing Airworthiness Management Organisation (CAMO) is responsible for ensuring that aircraft remain compliant, safe to operate and supported by complete, current technical records. Service Bulletins (SBs) and Airworthiness Directives (ADs) are central to that responsibility.

The CAMO does not normally perform the physical modification or inspection itself. Instead, it evaluates the technical instruction, determines its applicability, plans the required action and controls its completion through an approved maintenance organisation, such as a Part-145 or Part-CAO organisation. The CAMO must then demonstrate that the aircraft’s continuing-airworthiness status is accurately recorded.

For wider context, see our guide to how aircraft maintenance check intervals are determined, including AMP requirements, reliability data and regulatory instructions.

Understanding the difference between an SB and an AD

A Service Bulletin is issued by an aircraft, engine, equipment or component manufacturer. It may recommend:

• An inspection;
• A modification or replacement;
• A software or configuration change;
• A revised maintenance practice;
• A reliability improvement; or
• An optional safety or performance enhancement.

An SB is not automatically legally mandatory. Its status depends on factors including its classification, the applicable approval basis, the operator’s Aircraft Maintenance Programme (AMP), contractual requirements, lease conditions and any subsequent regulatory action.

An Airworthiness Directive is issued by the relevant aviation authority, typically the State of Design authority or the authority responsible for the aircraft’s operation or registration. The UK CAA Airworthiness Directives database provides applicable UK regulatory publications, while EASA’s Airworthiness Directives database provides European Union aviation safety directives. ADs are legally enforceable instructions intended to correct an unsafe condition or prevent its recurrence.

An AD may require compliance with a manufacturer’s SB, but it may also impose additional conditions, deadlines, inspection intervals or limitations. The CAMO must therefore assess the AD itself rather than treating the referenced SB as the complete compliance requirement.

The CAMO’s first responsibility: identifying applicable instructions

Effective management begins with controlled technical information. The CAMO should maintain processes for receiving and reviewing:

• UK CAA and EASA ADs;
• ADs from the State of Design, where relevant;
• Manufacturer SBs and revisions;
• Alert Service Bulletins and vendor notices;
• Component manufacturer instructions;
• Temporary revisions and technical instructions;
• Approved design changes and repair data; and
• Regulatory or manufacturer communications affecting continuing airworthiness.

The CAMO must establish whether each instruction applies to a particular aircraft, engine, propeller, appliance or installed configuration. This requires more than checking the aircraft type. Applicability may depend on:

• Aircraft, engine or component serial number;
• Modification status;
• Production standard;
• Software or hardware configuration;
• Previous embodiment of an SB;
• Operating role or equipment fit;
• Flight hours, cycles or calendar time; and
• The aircraft’s registration and applicable State of Registry requirements.

A controlled AD and SB register should record the technical instruction, affected asset, applicability assessment, compliance deadline, required action, method of compliance, current status and supporting evidence.

Assessing AD compliance

For each applicable AD, the CAMO must determine:

• What condition does the AD address?
• Which aircraft or components are affected?
• What is the compliance threshold or interval?
• What action is required?
• Is terminating action available?
• Are recurring inspections or tests required?
• What records and certification documents must be retained?
• Does compliance affect the AMP, aircraft limitations or operational control?

The compliance deadline may be expressed in flight hours, flight cycles, landings, calendar time or a combination of these. CAMO planning must account for the most restrictive applicable threshold and ensure that the required maintenance input is scheduled before the limit is reached.

Where an AD refers to an SB, the CAMO must verify the exact revision and any differences between the SB and the AD. A later SB revision does not automatically replace the version specified by an AD unless the applicable authority accepts that revision or the AD provides for it.

If an operator believes that an alternative method of compliance is necessary, the CAMO must use the applicable regulatory approval route. It cannot simply substitute an alternative inspection or modification because it appears technically equivalent. The relevant EASA continuing-airworthiness rules and guidance should be checked alongside the applicable UK CAA requirements.

Evaluating Service Bulletins

SB evaluation involves more than recording that a document has been received. The CAMO should assess:

• Whether the SB is mandatory through an AD;
• Whether it is already required by the AMP;
• Whether the manufacturer recommends it for safety or reliability reasons;
• Whether it affects the aircraft’s approved configuration;
• Whether it is required by a lease, customer or insurance arrangement;
• Whether it introduces a recurring maintenance task;
• Whether it affects operating limitations or performance; and
• Whether implementation creates new inspection, parts or tooling requirements.

The CAMO should apply a documented, risk-based decision process to non-mandatory SBs. A decision not to embody an SB should be justified, approved under the organisation’s procedures and periodically reviewed if operating experience, manufacturer advice or regulatory information changes.

An SB may become mandatory indirectly. For example, it may be incorporated into an AD, an approved maintenance programme, a life-limited component control process or an approved modification package. Once that occurs, the CAMO must manage it according to the resulting mandatory requirement rather than its original optional status.

Coordinating with Part-145 and Part-CAO organisations

The CAMO manages continuing airworthiness, while the approved maintenance organisation performs and certifies the physical work. This division of responsibility must be clearly controlled.

The CAMO normally provides the maintenance organisation with:

• The applicable AD or SB and revision;
• Aircraft and component configuration data;
• The approved work scope;
• The compliance deadline and priority;
• Required parts, tooling and technical data;
• Inspection or test requirements;
• Any required independent inspections; and
• The records and certification expected on completion.

The Part-145 or Part-CAO organisation then performs the maintenance in accordance with approved data and issues the relevant certification, such as a Certificate of Release to Service where applicable.

For related guidance, read about who can perform an independent inspection and how competence, authorisation and independence requirements apply.

The CAMO must review the returned records for completeness and technical consistency. Part-CAMO ensures that continuing-airworthiness records are complete, while Part-145 provides maintenance records, logbook entries and certification documents. The two record sets must reconcile. The work order, task cards, component documentation, release statement and aircraft records should all support the same compliance conclusion.

If the work is incomplete, incorrectly certified or performed using the wrong technical revision, the CAMO must not close the AD or SB action. It should raise the discrepancy with the maintenance organisation and control the issue through the organisation’s quality or safety procedures.

Safety and risk management at the CAMO and Part-145 interface

AD and SB management should be integrated into the organisation’s safety management system (SMS). Communication between the CAMO and Part-145 organisation should be risk-based, particularly where an instruction involves:

• A known failure mode;
• A time-critical inspection;
• A high-risk maintenance task;
• A significant change to aircraft configuration;
• Repetitive findings; or
• A potential effect on dispatch reliability or operational restrictions.

Part-145 must report maintenance errors and safety occurrences to the CAMO where they may affect continuing airworthiness. The CAMO should analyse those reports, assess whether other aircraft are exposed to the same risk and, where necessary, update maintenance planning or initiate further technical investigation. The SKYbrary overview of safety management systems provides useful industry context for integrating hazard identification and risk control into maintenance processes.

The CAMO also manages deferred defects and works with Part-145 on troubleshooting and rectification. A deferred defect must not be used to avoid compliance with an AD or an applicable mandatory inspection. Where an AD conflicts with an existing defect-control arrangement, the AD takes precedence.

For a practical overview of defect control, see our guide to how aircraft engineers defer defects using the MEL.

Updating the Aircraft Maintenance Programme

An AD or SB may require the CAMO to amend the AMP. This is particularly relevant where the instruction introduces:

• A new scheduled inspection;
• A repetitive task;
• A revised component replacement interval;
• A new functional check;
• A special inspection after a defined event; or
• A terminating modification that removes an existing task.

The CAMO must ensure that the AMP reflects the approved requirements and that the maintenance planning system generates the correct future tasks. Closing the initial SB or AD action is not sufficient if recurring compliance remains necessary.

Any change to the AMP must follow the applicable UK or EASA approval and acceptance process. The CAMO should also check whether the instruction affects reliability monitoring, aircraft records, minimum equipment arrangements or operational procedures.

Records, audits and airworthiness reviews

A CAMO must retain objective evidence that each applicable AD has been complied with and that SB decisions are controlled. Evidence may include:

• The applicable AD or SB revision;
• The applicability assessment;
• Engineering or technical evaluation;
• Approved work instructions;
• Task cards and inspection findings;
• Parts traceability documentation;
• Certificates of Release to Service;
• Photographs or measurement records, where required;
• Updated component and aircraft status records; and
• The next due date or terminating-action statement.

These records support internal audits, authority oversight, lease transitions and Airworthiness Reviews. Part-CAMO performs Airworthiness Reviews and monitors Part-145 compliance, but an airworthiness review is not a substitute for day-to-day AD and SB control. An aircraft cannot be considered airworthy merely because its records have been reviewed if a known mandatory instruction remains overdue or unsupported.

UK CAA continuing-airworthiness guidance should be consulted when confirming current requirements for records, airworthiness reviews and organisational procedures.

CAP 2153, published by the UK CAA in March 2026, also highlights the need for demonstrable continuing-airworthiness control in the context of permits to fly and Certificates of Airworthiness. It states that a relevant privilege may be exercised for two consecutive periods of one year by an authorised signatory listed in paragraph 5.2 of the CAME, subject to conditions including that:

• The aircraft has been continuously managed by the CAMO for the previous 12 months; and
• The aircraft has been maintained for the previous 12 months by approved maintenance organisations, including permitted pilot-owner maintenance tasks released to service by the pilot-owner or independent certifying staff.

The same CAP states that the CAMO should establish procedures to ensure and demonstrate that any required maintenance has been completed before a Permit to Fly is issued. This includes demonstrating compliance with approved procedures, contracted maintenance arrangements, applicable Part-CAMO, Part-ML and Part-M requirements, and Part-145 or Part-CAO requirements where applicable.

In practical terms, unresolved AD or SB actions can affect more than the maintenance status of an individual task. They may influence the CAMO’s ability to demonstrate continuing compliance during an airworthiness review or permit-to-fly process.

Keep your maintenance records organised with Part 66 Logbook Analysis, designed to help aviation professionals review logbook evidence and support Part 66 compliance.

Managing changes in UK and EASA requirements

UK-registered and EASA-registered aircraft may be subject to different implementing rules and authority publications. A CAMO must identify the relevant State of Registry, State of Design and operating approvals rather than applying a generic AD database without review.

The CAMO should monitor amendments to the applicable AMC and GM, including updates to Part-CAMO and Part-ML. UK CAA publication updates in 2026 included amendments to AMC and GM to Part-CAMO, Part-ML and Part-66. Although Part-66 primarily concerns certifying-staff licensing rather than CAMO control, changes to associated guidance can affect how competence, records and maintenance responsibilities are understood across the continuing-airworthiness system.

For aircraft moving between UK, EASA and other regulatory systems, the CAMO must reconcile the aircraft’s existing compliance history with the requirements of the new State of Registry. Imported aircraft may require a detailed review of Part 21 Subpart H documentation, prior AD compliance, approved modifications and the status of recurring SB actions.

See our guide to EASA Form 1 after Brexit for related information on UK organisation approvals, component release and regulatory control.

The professional standard expected of a CAMO

Effective AD and SB management is a controlled lifecycle, not an administrative checklist:

• Receive and control the latest technical information.
• Determine applicability to the aircraft or component.
• Assess mandatory status, risk and operational consequences.
• Plan the work before the compliance limit.
• Contract and brief the approved maintenance organisation.
• Verify the technical execution and certification.
• Update aircraft, component and AMP records.
• Control recurring actions and terminating modifications.
• Report relevant errors, occurrences and safety risks.
• Demonstrate compliance during audits and airworthiness reviews.

The CAMO’s central role is to maintain an accurate, defensible link between the regulatory requirement, the aircraft’s configuration, the maintenance action and the evidence of completion. When that link is properly controlled, SBs and ADs become part of a reliable continuing-airworthiness system rather than isolated technical documents awaiting action.

For more aircraft maintenance and continuing-airworthiness guidance, visit the AeroTech Careers Blog.