--- title: "Service Bulletin Evaluation in a CAMO · Avioverse" description: "Evaluate a service bulletin’s applicability, benefits, cost and risk of non-application, distinguish it from an AD and record the CAMO decision and follow-up." url: "https://avioverse.aero/guides/service-bulletin-evaluation-camo" --- # Service Bulletin Evaluation: Benefits, Risk and the CAMO Decision Evaluate a service bulletin’s applicability, benefits, cost and risk of non-application, distinguish it from an AD and record the CAMO decision and follow-up. [Dionysis Kefalas](https://avioverse.aero/articles/author/dennis-kefalas) 21 Oct 2026 8 min read For CAMO, Part-145 and Air Ops staff Part 10 of 12 in EASA Continuing Airworthiness Show parts Hide parts 1. 1 [Continuing Airworthiness: Part-M and Part-CAMO](https://avioverse.aero/guides/easa-continuing-airworthiness-explained) 2. 2 [Aircraft Maintenance Programme under Part-M](https://avioverse.aero/guides/easa-aircraft-maintenance-programme-amp) 3. 3 [EASA Reliability Programmes and Monitoring](https://avioverse.aero/guides/easa-reliability-programme-monitoring) 4. 4 [Airworthiness Reviews and the ARC](https://avioverse.aero/guides/easa-airworthiness-review-certificate-arc) 5. 5 [CAMO, CAO and Part-145: Roles Compared](https://avioverse.aero/guides/easa-camo-continuing-airworthiness-management-organisation) 6. 6 [Part-M: Release to Service and Records](https://avioverse.aero/guides/easa-maintenance-release-to-service-records) 7. 7 [EASA Airworthiness Directives and AD Compliance](https://avioverse.aero/guides/easa-airworthiness-directives-ad-compliance) 8. 8 [LLP Back-to-Birth Records and M.A.305 Tracking](https://avioverse.aero/guides/aircraft-component-records-life-limited-parts) 9. 9 [Aircraft Reliability Programme, Step by Step](https://avioverse.aero/guides/aircraft-reliability-programme-step-by-step) 10. 10 Service Bulletin Evaluation in a CAMO 11. 11 [CAMO Staff Competence and Manpower Planning](https://avioverse.aero/guides/camo-staff-competence-assessment-manpower) 12. 12 [CAMO Subcontracting and Maintenance Contracts](https://avioverse.aero/guides/camo-subcontracting-maintenance-contract) Quotes checked on 21 Oct 2026 against 2 sources. Show sources Hide sources - EASA Easy Access Rules for Continuing Airworthiness (Regulation (EU) No 1321/2014) — 2 Sep 2025 revision - EASA Easy Access Rules for Initial Airworthiness and Environmental Protection (Regulation (EU) No 748/2012, Part-21) — 27 Nov 2025 revision On this page ## An AD decision and an SB decision answer different questions An airworthiness directive (AD) mandates action. A service bulletin (SB) is not mandatory merely because it has been issued. The first job is to establish whether an applicable AD requires the bulletin’s action; only then can the reviewer decide whether there is a discretionary choice to make. | Evaluation | Question the decision must answer | Role of cost and resources | | ---------------- | ---------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------- | | Applicable AD | Does it cover these aircraft or parts, what actions are required, and how and by when will they be accomplished? | Plan compliance within the AD’s requirements. Cost does not create a choice to decline. | | Non-mandatory SB | What benefit would applying it bring, and how tolerable is the risk if it is declined or postponed? | Weigh safety, reliability, economic and operational effects, including cost, man-hours and downtime. | That distinction follows the definition in Part-21 and the continuing-airworthiness obligation: [21.A.3B(a) (full rule text)](https://avioverse.aero/regulations/easa/initial-airworthiness/annex-i/section-a-technical-requirements/21-a-3b) Airworthiness directives > (a) An airworthiness directive means a document issued or adopted by the Agency which mandates actions to be performed on an aircraft or on a CMU to restore an acceptable level of safety, when evidence shows that the safety level of the aircraft, UAS or CMU may otherwise be compromised. Quoted word for word from Regulation (EU) No 748/2012, Easy Access Rules for Initial Airworthiness, 27 Nov 2025 revision. [M.A.303 (full rule text)](https://avioverse.aero/regulations/easa/continuing-airworthiness/part-m/section-a-technical-requirements/m-a-303) Airworthiness directives > Any applicable airworthiness directive must be carried out within the requirements of that airworthiness directive, unless otherwise specified by the Agency. Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision. The [AD compliance guide](https://avioverse.aero/guides/easa-airworthiness-directives-ad-compliance) covers applicability, controlling limits and completion evidence. Keep those requirements controlling when an AD calls up an SB action. Choosing “Do not apply” in an evaluation cannot override the AD. For a non-mandatory action, use the Service bulletin evaluation to record the technical case, the safety review and the decision. The form connects **Expected benefits** with **Tolerability if not applied**: what the change would improve, and what happens if the organisation does not make it. ## Who needs the assessment procedure? [CAMO.A.315(b)(4) (full rule text)](https://avioverse.aero/regulations/easa/continuing-airworthiness/part-camo/section-a-organisation-requirements/camo-a-315) Continuing airworthiness management > \[…] > > (b) For every aircraft managed, the organisation shall in particular: > > \[…] > > (4) for all complex motor-powered aircraft or aircraft used by air carriers licensed in accordance with Regulation (EC) No 1008/2008, establish a procedure to assess non-mandatory modifications and/or inspections and decide on their application, making use of the organisation’s safety risk management process as required by point (a)(3) of point CAMO.A.200; > > \[…] Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision. The scope is **complex motor-powered aircraft or aircraft used by licensed air carriers**. Either condition brings the aircraft within point (b)(4). Do not turn that wording into a rule limited to complex aircraft operated by airlines, or into a universal requirement for every aircraft managed by a CAMO. The associated acceptable means of compliance identifies the information to assess: [AMC1 CAMO.A.315(b)(4) (full rule text)](https://avioverse.aero/regulations/easa/continuing-airworthiness/part-camo/section-a-organisation-requirements/camo-a-315#amc1-camo-a-315-b-4) Assessment of non-mandatory information > ASSESSMENT OF NON-MANDATORY INFORMATION > > The CAMO managing the continuing airworthiness of the aircraft should establish and work according to a policy, which assesses non-mandatory information (modification or inspections) related to the airworthiness of the aircraft. Non-mandatory information refers to service bulletins, service letters and other information that is produced for the aircraft and its components by an approved design organisation, the manufacturer, the competent authority or the Agency. Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision. Start with the bulletin’s revision, affected aircraft and parts, and related ADs. Compare its effectivity with the actual configuration. A manufacturer’s recommendation and an AD obligation have different consequences; record the actual relationship rather than relying on a publication’s label. ## Weigh the benefit and the risk of non-application **Expected benefits** asks the reviewer to make the case for applying the bulletin explicit. The following are practical decision aids, not a scoring method prescribed by CAMO.A.315(b)(4): - **Safety:** identify the hazard the action addresses, the supporting evidence and the expected reduction in risk. - **Reliability:** examine recurring defects, removals or interruptions that the change may reduce, using the aircraft’s operating experience where available. - **Economic:** compare parts and labour costs, man-hours, downtime and any continuing maintenance burden with the expected savings. State what the estimate includes. - **Operational:** explain whether the change would affect availability, operating restrictions or the way the aircraft is used. Record uncertainty and alternatives in the evaluation narrative. For example, applying a modification at the next planned maintenance input may have a different downtime cost from a dedicated input. That comparison still needs a separate assessment of the risk during the waiting period. **Tolerability if not applied** covers both declining the SB and postponing it beyond its stated compliance limits. For a non-mandatory bulletin, assess the consequences of going beyond the bulletin’s recommendation. Where an AD requires the action, its mandatory limits still govern under M.A.303. [CAMO.A.200(a)(3) (full rule text)](https://avioverse.aero/regulations/easa/continuing-airworthiness/part-camo/section-a-organisation-requirements/camo-a-200) Management system > (a) The organisation shall establish, implement, and maintain a management system that includes: > > \[…] > > (3) the identification of aviation safety hazards entailed by the activities of the organisation, their evaluation and the management of associated risks, including taking actions to mitigate the risks and verify their effectiveness; > > \[…] Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision. A category alone is not the assessment. Use the organisation’s risk criteria, identify the evidence, describe any controls and explain how their effectiveness will be checked. In the form’s practical conventions, **Acceptable** needs no further risk reduction, **Tolerable** needs specified controls and review, and **Intolerable** needs risk reduction before acceptance. **Not assessed** means no judgement has been made. These labels do not create permission to ignore an unresolved safety concern. ## Why the form asks what it asks **Document identity and related publications** make the evaluation reproducible. A reviewer needs to know which issue, revision and supporting information led to the recommendation. The related-AD check separates discretionary evaluation from the obligations in M.A.303 and the actions and compliance times identified by 21.A.3B(d). **Product, effectivity and publication recommendation** define the aircraft or parts assessed. Explain exclusions and earlier embodiment in the narrative, with references to the evidence. A conclusion for one configuration should not silently become a decision for the whole fleet. **Benefits, maintenance impact and resources** connect the reason for the bulletin to the proposed action. The expected-benefit choices prompt the safety, reliability, economic and operational comparison. The recurring-task check exposes work that may continue after embodiment. Use the narrative for downtime and alternatives alongside the cost and man-hour estimates; not every consideration needs a separate question. **Risk reference and tolerability** connect the recommendation to the safety risk management process required by CAMO.A.315(b)(4) and CAMO.A.200(a)(3). The reference should lead to the assessment and its evidence. Where controls or further review are needed, record what they are, who will follow them up and what would change the decision. **Recommendation and grounds** turn the analysis into a reviewable proposal: apply, schedule for a defined opportunity, decline, monitor or record non-applicability. Explain why the chosen course follows from the evidence. A practical review trigger might be a bulletin revision, an increase in related defects, a change of operation or new safety information. The rule does not prescribe those particular triggers; they make the organisation’s decision revisitable. ## A fictional evaluation across CAMO, maintenance and operations ExampleAir’s CAMO is assessing a non-mandatory equipment modification for MSN-EXAMPLE-014. No applicable AD requires the action in this fictional case. ExampleMRO supplies an estimate of 12 man-hours and one day of aircraft downtime. Operations provides evidence of recurring dispatch interruptions, and the CAMO checks the defect history and the proposed configuration change. The evaluation records a likely reliability and operational benefit. Its economic case compares a dedicated maintenance input with embodiment during the next planned input. The safety manager examines the risk of waiting beyond the bulletin’s recommended date, including any controls and evidence needed during that period. If the evidence does not support the proposed tolerability judgement, the recommendation goes back for changes. A decision to use the next planned input records why that timing is acceptable under the organisation’s criteria, what would trigger an earlier review and who owns the follow-up. An estimate that the modification will save money is useful evidence; it is not, by itself, the safety assessment. ## Safety review, decision and close-out The form separates three written follow-up sections. The **safety manager** reviews the risk assessment, tolerability, controls and review arrangements. The **continuing airworthiness manager** records the application decision and its grounds, checking any AD obligations before accepting postponement or non-application. **Planning or technical records staff** record the work arrangements, communications, record updates and any remaining monitoring. In Avioverse, each section is assigned to a workspace member, who records **Approve** or **Request changes** with a comment, or **Not required** with a reason. Only workspace members can be assignees. A supplier or maintainer outside the workspace provides information through the organisation’s usual arrangements; a member records it in the evaluation. An internal Approve response records a decision, not authority permission to depart from a mandatory requirement. Implementation has its own follow-through. CAMO.A.315(b)(1) requires the AMP, including any applicable reliability programme, to be developed and controlled. Points (b)(5)–(6) address arranging appropriate maintenance, ordering and supervising it, and coordinating the related decisions. Under M.A.302(h), the AMP is periodically reviewed and amended when necessary in light of operating experience and new or modified instructions. If the SB changes recurring work, link the evaluation to the [AMP change and amendment process](https://avioverse.aero/guides/easa-aircraft-maintenance-programme-amp). For embodiment, connect close-out to the work order and completion evidence described in [maintenance, release to service and records](https://avioverse.aero/guides/easa-maintenance-release-to-service-records). For a declined or monitored bulletin, close-out should leave the reason and any review trigger clear to the next person reading it. ## Where to read it yourself The assessment and risk-management provisions are CAMO.A.315(b)(4), its AMC1, and CAMO.A.200(a)(3); AMP review is M.A.302(h), and the AD obligation is M.A.303. These were checked against the **2025-09-02 revision** of the EASA Easy Access Rules for Continuing Airworthiness. The AD definition and minimum contents are in 21.A.3B(a) and (d), checked against the **2025-11-27 revision** of the Easy Access Rules for Initial Airworthiness and Environmental Protection. The benefit categories, form roles and example are practical ways to organise the work. ## Forms in this guide ### Airworthiness - Service bulletin evaluation Assess a service bulletin or other non-mandatory modification or inspection, review its risk and record whether to apply it. | Question | Answer type | Required | | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------- | -------- | | Document type | Choice: Service bulletin, Vendor service bulletin, Service letter or information letter, Other non-mandatory modification or inspection | Yes | | Document number | Short answer | Yes | | Revision | Short answer | No | | Issue date | Date | No | | Issuer (design approval holder or manufacturer) | Short answer | Yes | | Subject | Short answer | Yes | | Related ADs and other documents | Long answer | No | | Product category | Choice, one or more: Aircraft, Engine, Propeller, APU, Appliance or component | Yes | | Type or model | Short answer | No | | Aircraft or parts covered by this evaluation Identify the aircraft or parts assessed and explain exclusions in the evaluation. | Long answer | Yes | | Publication recommendation or AD link Record the actual recommendation and any AD link in the evaluation. Any applicable AD requirements remain controlling. | Choice: Linked to an AD, Recommended, Optional, For information only, Other or not stated | No | | Additional recurring maintenance programme tasks | Tick box | No | | Expected benefits Select every benefit expected from applying the bulletin, then describe and weigh them below. | Choice, one or more: Safety, Reliability, Economic (cost, man-hours or downtime), Operational, None identified | No | | Basis for the bulletin and expected benefit | Long answer | No | | Suggested decision For an AD-linked action, record a proposal consistent with the AD requirements. A risk assessment does not authorise exceeding an AD limit. | Choice: Apply, Apply at the next opportunity, Apply when the part is next removed, Do not apply, Monitor, no action now, Not applicable | Yes | | Estimated man-hours | Number | No | | Estimated cost Include the currency and state what the estimate covers. | Short answer | No | | Tolerability if not applied (declined, or postponed beyond the compliance limits) Using the organisation's risk criteria: Acceptable needs no further risk reduction; Tolerable needs specified controls and review; Intolerable needs risk reduction before acceptance. Not assessed means no judgement has been made. | Choice: Acceptable, Tolerable, Intolerable, Not assessed | No | | Evaluation and grounds | Long answer | Yes | Once a response is submitted, the form opens these follow-up steps: - Risk assessment - Decision - Close-out Educational content, not regulatory compliance advice. Verify against the current regulation text before relying on it. ## In this series ## Frequently asked questions ### How does an SB evaluation differ from an AD evaluation? An applicable AD is mandatory: establish applicability, the required actions and how and by when to comply. A non-mandatory SB evaluation weighs the benefit of applying it and the risk of declining or postponing it. Check related ADs before treating the SB decision as discretionary. ### Is a service bulletin mandatory because it has been issued? No. AMC1 CAMO.A.315(b)(4) includes service bulletins in non-mandatory information. Where an applicable AD requires an SB action, that action must follow the AD’s requirements under M.A.303; a cost or risk assessment does not override them. ### Which aircraft need the non-mandatory assessment procedure? CAMO.A.315(b)(4) requires it for all complex motor-powered aircraft or aircraft used by air carriers licensed under Regulation (EC) No 1008/2008. The application decision must use the organisation’s safety risk management process. ### What benefits should an SB evaluation consider? Consider safety, reliability, economic and operational benefits, supported by evidence. Include cost, man-hours, downtime, maintenance impact and alternatives. These are practical decision categories, not a regulatory scoring formula. ### What does tolerability if not applied mean? It records the judgement, under the organisation’s risk criteria, about declining the bulletin or postponing it beyond its stated compliance limits. Describe the risk, controls and review trigger behind that judgement. Not assessed means no judgement has been made; it is not an acceptable-risk conclusion. ### Does accepting an SB evaluation update the maintenance programme? No. The evaluation records the decision and follow-up. Any necessary AMP change still goes through the programme’s amendment and approval process. Close-out should connect the decision to maintenance planning, records and any monitoring that remains. ## Related - [EASA airworthiness directives: AD compliance explained Guide · 21 min](https://avioverse.aero/guides/easa-airworthiness-directives-ad-compliance) - [Aircraft maintenance programme under Part-M Guide · 10 min](https://avioverse.aero/guides/easa-aircraft-maintenance-programme-amp) - [Reliability programmes and monitoring Guide · 5 min](https://avioverse.aero/guides/easa-reliability-programme-monitoring) - [CAMO, CAO and Part-145: roles and responsibilities Guide · 7 min](https://avioverse.aero/guides/easa-camo-continuing-airworthiness-management-organisation) - [Maintenance, release to service and records Guide · 11 min](https://avioverse.aero/guides/easa-maintenance-release-to-service-records) - [Hazard identification and safety risk management Guide · 17 min](https://avioverse.aero/guides/easa-hazard-identification-safety-risk-management) - [CAMO staff competence assessment and manpower planning Guide · 9 min](https://avioverse.aero/guides/camo-staff-competence-assessment-manpower) - [CAMO contracting and subcontracting: CAMO.A.205 and maintenance contracts Guide · 10 min](https://avioverse.aero/guides/camo-subcontracting-maintenance-contract) Written by Dionysis Kefalas. Retired Hellenic Air Force Captain and founder of Avioverse. [About the author](https://avioverse.aero/articles/author/dennis-kefalas) [Or request early access →](https://avioverse.aero/register?redirect=https%3A%2F%2Fapp.avioverse.aero%2Fforms) Share [LinkedIn](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Favioverse.aero%2Fguides%2Fservice-bulletin-evaluation-camo)[X](https://twitter.com/intent/tweet?url=https%3A%2F%2Favioverse.aero%2Fguides%2Fservice-bulletin-evaluation-camo\&text=Service%20Bulletin%20Evaluation%20in%20a%20CAMO)