The Real-World Question
Picture a typical base maintenance facility. A C-check is in progress on a Boeing 737. The Category C certifying engineer overseeing the event also holds a valid B1 licence with the appropriate type rating. Staffing is tight. Rather than waiting for an available B1 support staff member, the C engineer rolls up their sleeves, performs a landing gear inspection, signs the task card as B1 support staff, and later that same day issues the Certificate of Release to Service (CRS) for the entire aircraft as C certifying staff.
Is this legal? Is it ethical? And what risks does it introduce?
This scenario is more common than many in the industry would like to admit, particularly in small-to-medium Part-145 organisations where staffing constraints and commercial pressures create conditions for role overlap. This article examines what the regulation says, where it is silent, and how Part-145 organisations should manage the risks.
What Does EU 1321/2014 Actually Say?
The regulatory framework for base maintenance certification is established in 145.A.30(h)(1) of EU Regulation 1321/2014 (Annex II, Part-145). For base maintenance of complex motor-powered aircraft, the organisation must have Category C certifying staff supported by sufficient B1 and B2 support staff. The regulation establishes a clear three-tier verification model:
Authorised persons carry out the maintenance tasks and sign them off.
B1/B2 support staff verify that all relevant tasks or inspections within their discipline have been carried out to the required standard.
- Category C certifying staff ensure that all maintenance ordered has been accomplished (or properly deferred), that the support staff have completed their verification, and then issue the CRS for the aircraft.
This layered structure is not arbitrary. It was designed to create independent verification barriers — each layer checks the work of the layer below. The EASA Policy Paper on the roles and responsibilities of personnel involved in aircraft maintenance (March 2023) makes this architecture explicit in its Figure 1, illustrating the flow from task performance through support staff verification to C certifying staff oversight and CRS issuance.
Critically, 145.A.30(h)(1)(i) states that B1 and B2 support staff shall ensure all relevant tasks have been carried out to the required standard before the C certifying staff issues the CRS. The AMC material further clarifies that the principal function of category C certifying staff is to ensure that all required maintenance has been called up and signed off by the B1 and B2 support staff. The C engineer’s role is fundamentally one of oversight and final verification, not hands-on task execution.
The Silent Gap: What the Regulation Does Not Prohibit
Here is the crucial point: the regulation does not explicitly prohibit a person who holds both a C licence and a B1 (or B2) licence from acting in both capacities on the same maintenance event.
The March 2023 EASA Policy Paper acknowledges in its Note 3 that a person may hold different roles depending on the maintenance event — for instance, acting as support staff on one aircraft and certifying staff on another. However, the Paper does not directly address the scenario where the same person performs both roles on the same event. This silence has been interpreted by some organisations as tacit permission.
But regulatory silence is not the same as regulatory approval. The entire architecture of 145.A.30(h)(1) is built on the assumption that different individuals occupy each tier. When one person performs a task as B1 support staff and then verifies their own work as C certifying staff, the independent verification barrier collapses. The person issuing the CRS is effectively confirming that their own work was performed to the required standard — a circular assurance that undermines the purpose of the layered system.
Where the Risk Lives: Independence and Conflict of Interest
The Technical Risk
When the same engineer performs task-level work and then issues the aircraft-level CRS, the organisation loses a fundamental safety barrier. Human Factors research consistently demonstrates that people are poor at detecting their own errors. The layered verification system exists precisely because a second set of eyes catches what the first pair missed. Remove that separation, and error capture rates decline.
The Commercial Risk
The commercial dimension is equally concerning. In many small-to-medium Part-145 organisations, the C certifying engineer is also the hangar foreman, production shift leader, or base maintenance manager. While this is not universal — larger MROs typically separate production management from certification authority — it is common enough to warrant serious attention.
When these roles overlap, the person releasing the aircraft to service may be the same person whose performance is measured against commercial KPIs: turnaround time (TAT), aircraft-on-ground (AOG) recovery, hangar slot utilisation, or even direct financial bonuses linked to on-time delivery. This creates a structural conflict of interest. The individual’s commercial incentives pull in one direction (release the aircraft quickly) while their certification duty requires them to stop and defer work if necessary.
This is not about questioning any individual’s integrity. The vast majority of certifying engineers take their responsibilities seriously. The issue is systemic: good safety management does not rely on individual virtue — it builds organisational defences that protect against the moments when commercial pressure, fatigue, or time constraints cloud judgement.
EASA itself has recognised the conflict-of-interest principle in a closely related context. In its FAQ on airworthiness review staff (ARS) under Part-CAMO, the Agency recommends ensuring the absence of conflict of interest when ARS conducts airworthiness reviews on aircraft they previously released as certifying staff. The same principle applies with equal force to the dual-role C/B1 scenario in base maintenance.
Managing the Risk Through SMS and the MOE
Given that the regulation does not impose an outright prohibition, the answer is not to pretend the scenario never arises. Instead, Part-145 organisations should treat this as a safety risk to be assessed and mitigated under their Safety Management System (SMS) in accordance with 145.A.200.
Practical mitigations that organisations should consider include:
- Separate commercial KPIs from certification authority. Where the C certifying engineer also holds a production management role, ensure that their performance appraisal and any bonus structure are not tied to TAT or delivery targets. The certification authorisation must remain demonstrably independent of commercial pressure.
- Require independent verification of self-performed tasks. If the C engineer has performed any task-level work as B1 or B2 on the same maintenance event, the MOE should require a different B1/B2 support staff member to verify that specific work before the CRS is issued. The C engineer should not verify their own task cards.
- Document the policy explicitly in the MOE. The Maintenance Organisation Exposition should contain a clear procedure addressing dual-role scenarios. Ambiguity invites inconsistency. The procedure should define under what circumstances (if any) dual-role activity is permitted, what mitigations apply, and how the compliance monitoring function will audit this.
- Include this scenario in the compliance monitoring audit programme. The Compliance Monitoring Manager should ensure that audits specifically target dual-role activity, reviewing CRS records against task card signatures to identify patterns where the same individual appears in both roles.
- Use occurrence and hazard reporting to capture pressure events. Encourage staff to report situations where commercial pressure influenced certification decisions. This data feeds directly into the SMS hazard register and allows the organisation to identify systemic issues before they result in an incident.
Key Takeaway
The dual-role scenario is not explicitly prohibited by EU 1321/2014, but it undermines the independent verification architecture that the regulation was designed to establish. Organisations must treat it as a safety risk, assess it through their SMS, and implement clear mitigations in their MOE
Conclusion: Legal Does Not Mean Risk-Free
The question of whether a C-certifying engineer can also act as B1/B2 support staff on the same base maintenance event does not have a simple yes-or-no answer. The regulation does not explicitly prohibit it. But the regulatory architecture, the EASA Policy Paper of March 2023, and established conflict-of-interest principles all point to the same conclusion: this practice introduces risk that must be actively managed.
Organisations that allow dual-role activity without procedural safeguards are exposing themselves to audit findings, regulatory scrutiny, and — most importantly — a degradation of the verification barriers that protect aircraft safety. Those that address the issue proactively through their SMS, MOE procedures, and compliance monitoring programme will be in a far stronger position.
There is also a case for EASA to issue clarifying Acceptable Means of Compliance (AMC) or Guidance Material (GM) on this topic. The current regulatory silence leaves room for divergent interpretations across Member States and organisations. Clear guidance would benefit the entire industry.
References
1. EU Regulation 1321/2014, Annex II (Part-145), points 145.A.30(h), 145.A.35, 145.A.50, 145.A.200.
2. EASA Easy Access Rules for Continuing Airworthiness (Regulation (EU) No 1321/2014).
3. EASA Policy Paper: Roles and Responsibilities of Personnel Involved in Aircraft Line and Base Maintenance, March 2023.
4. EASA FAQ 19049: Conflict of Interest — Airworthiness Review Staff and Certifying Staff.
5. EU Regulation 1321/2014, Annex III (Part-66), point 66.A.20 — Privileges.
Need support with Part-145 compliance, SMS implementation, or certifying staff authorisation procedures?
AviaThrust Training & Consultancy provides specialist aviation regulatory training, compliance auditing, and MOE development services. Contact us at george.spiteri@aviathrust.com or visit www.aviathrust.com to learn more.
