Module 10: Aviation Legislation — B1.3 Helicopter Turbine

Overview

Module 10 provides the foundational regulatory knowledge required for aircraft maintenance certifying staff. For the B1.3 category (helicopter turbine), this module covers the European Union regulatory framework governing civil aviation, with particular emphasis on:

The structure and hierarchy of EU aviation regulations

The Part-66 licensing system for maintenance personnel

The Part-145 maintenance organisation approval system

The Part-M continuing airworthiness framework

The Part-21 design and production requirements

The relationship between operational regulations (Part-CAT) and maintenance regulations

This module ensures that certifying staff understand not only what they are required to do, but why the regulatory framework exists and how the various regulations interrelate.

1. The Regulatory Framework

1.1 The European Union Aviation Safety Agency (EASA) System

The European aviation regulatory framework is built upon Regulation (EU) 2018/1139, which established EASA and provides the legal basis for all implementing rules. The principal implementing regulation for continuing airworthiness is Regulation (EU) No 1321/2014, which contains four key annexes:

Annex	Content
Annex I (Part-M)	Continuing airworthiness requirements for aircraft
Annex II (Part-145)	Approval of maintenance organisations
Annex III (Part-66)	Certification of maintenance personnel
Annex IV (Part-147)	Training organisations for maintenance personnel

1.2 Regulation Hierarchy

The regulatory structure follows a clear hierarchy:

18.Basic Regulation (EU) 2018/1139 — establishes EASA and general principles

19.Implementing Rules — detailed technical requirements (e.g., Part-66, Part-145, Part-M)

20.Acceptable Means of Compliance (AMC) — non-binding but recognised methods of compliance

21.Guidance Material (GM) — explanatory material to assist understanding

22.Certification Specifications (CS) — technical standards for airworthiness

> Key Point: AMC and GM do not have the force of law, but compliance with them provides a presumption of compliance with the associated implementing rule.

2. Part-66 — Aircraft Maintenance Licence

2.1 Licence Categories and Subcategories

Part-66 (Annex III to Regulation (EU) No 1321/2014) defines the following licence categories:

Category	Scope
A	Line maintenance certifying staff — simple tasks and defect rectification
B1	Mechanical maintenance certifying staff — airframe, engine, mechanical and electrical systems
B2	Avionics maintenance certifying staff — communication, navigation, instrumentation, electrical systems
B3	Non-pressurised piston-engine aeroplanes below 2000 kg MTOM
C	Base maintenance certifying staff — release to service of complete aircraft

Subcategories of B1:

B1.1 — Aeroplanes with turbine engines

B1.2 — Aeroplanes with piston engines

B1.3 — Helicopters with turbine engines

B1.4 — Helicopters with piston engines

2.2 Privileges of a B1.3 Licence Holder

Per Part-66.A.20(a), a B1.3 licence holder is authorised to:

Certify maintenance on helicopter turbine engines and associated mechanical systems

Certify maintenance on helicopter airframes, including structural repairs

Certify work on mechanical and electrical systems (but not avionics systems, which require a B2 licence)

Issue Certificates of Release to Service (CRS) following maintenance

Act as support staff for category C certifying staff during base maintenance

> Important Distinction: The B1.3 licence covers mechanical and electrical systems but excludes avionics (radio, navigation, instruments, and autopilot systems). A B2 licence is required for avionics certification.

2.3 Eligibility Requirements for Licence Issue

Part-66.A.25 establishes the fundamental eligibility criteria:

Requirement	Detail
Minimum age	18 years
Basic knowledge	Pass all modules of the Part-66 basic knowledge examination
Practical experience	Minimum 3 years (B1.3), reduced to 2 years with an approved Part-147 basic training course
Type training	Not required for initial licence issue, but required for type ratings

2.4 Practical Experience Requirements

Part-66.A.30 specifies the practical experience requirements:

Standard requirement (B1.3): 3 years of practical maintenance experience on operating helicopters

With Part-147 approved basic training: 2 years of practical experience

Experience composition: Must include a representative cross-section of maintenance tasks relevant to helicopter turbine aircraft

The experience must be gained on operating aircraft (not new or stored aircraft) and should include:

Routine scheduled maintenance

Defect rectification

Component replacement

Functional testing

2.5 Licence Validity and Recent Experience

Part-66.A.20(b) and Part-66.B.100 establish the conditions for exercising certification privileges:

> Recent Experience Requirement: The licence holder must have 6 months of relevant maintenance experience in the preceding 2-year period to exercise certification privileges.

Important Clarification: The licence itself does not expire and is issued without a time limit. However, the privileges cannot be exercised without meeting the recent experience requirement.

If the holder has not used certification privileges for more than 2 years:

A refresher training course must be completed

An examination must be passed

Only then may certification privileges be exercised again

2.6 Type Ratings

Part-66.A.45 defines the requirements for type ratings:

Type rating training must be completed at a Part-147 approved training organisation (or equivalent)

Training includes both theoretical and practical elements

An examination must be passed

The type rating is endorsed on the licence

For B1.3, the type rating includes:

The specific helicopter type (e.g., Airbus H135, Leonardo AW139)

The related turbine engine type(s)

Associated mechanical and electrical systems

> Key Point: A type rating is required for certifying maintenance on type-rated aircraft. However, for non-type-rated engines, a B1.3 licence allows certification of minor scheduled maintenance and simple defect rectification.

2.7 Licence Structure and Endorsements

The Part-66 licence format includes:

Personal details of the holder

Categories and subcategories held (e.g., B1.3)

Type ratings for specific aircraft types

Limitations (if any)

National endorsements (if applicable)

3. Part-145 — Maintenance Organisation Approvals

3.1 Purpose and Scope

Part-145 (Annex II to Regulation (EU) No 1321/2014) governs the approval of maintenance organisations. A Part-145 approval is required for:

Maintenance of aircraft used in commercial air transport (CAT)

Maintenance of aircraft above 5700 kg MTOM

Any organisation that chooses to operate under Part-145

3.2 Certifying Staff Requirements

Part-145.A.30 and Part-145.A.35 establish the requirements for certifying staff:

Requirement	Detail
Qualification	Hold an appropriate Part-66 licence (or national licence per transitional arrangements)
Employment	Must be employed by the organisation (or contracted per specific conditions)
Scope	Certification privileges limited to the organisation's scope of work
Records	The organisation must maintain records of certifying staff qualifications

3.3 Certification of Maintenance

Part-145.A.50 establishes the requirements for certification of maintenance:

> A Certificate of Release to Service (CRS) shall be issued only after all required maintenance has been properly carried out in accordance with the approved data specified in Part-145.A.45.

Key Principles:

The CRS is the formal declaration that maintenance has been performed correctly

The CRS must be issued by authorised certifying staff

A CRS cannot be issued if any required maintenance task is incomplete

Deferral of maintenance is only possible through the operator's Minimum Equipment List (MEL) or approved maintenance programme

3.4 Responsibilities of the Maintenance Organisation

Per Part-145.A.35, the organisation must:

Employ certifying staff qualified per Part-66

Provide appropriate facilities, equipment, and data

Ensure certifying staff have current knowledge of relevant regulations

Maintain records of certifying staff authorisations

Ensure that certifying staff are not subject to undue pressure

3.5 Approved Maintenance Data

Part-145.A.45 requires that all maintenance be performed using approved maintenance data:

Manufacturer's maintenance manuals (AMM, EMM, etc.)

Service Bulletins (SBs) and Airworthiness Directives (ADs)

Approved repair schemes

The operator's approved maintenance programme

> Critical Point: Certifying staff must follow the manufacturer's procedures exactly. They do not have the authority to deviate from approved data or make airworthiness decisions beyond what the data permits.

4. Part-M — Continuing Airworthiness Requirements

4.1 Purpose and Scope

Part-M (Annex I to Regulation (EU) No 1321/2014) establishes the continuing airworthiness requirements for aircraft, including:

Maintenance programme development and approval

Continuing airworthiness management

Airworthiness reviews

Maintenance performance requirements

4.2 Responsibilities of Owners and Operators

Part-M.A.301 and Part-M.A.305 establish that:

The owner or CAMO (Continuing Airworthiness Management Organisation) is responsible for ensuring maintenance is performed using approved data

The maintenance organisation is responsible for performing the work correctly

The certifying staff are responsible for certifying that the work has been completed correctly

4.3 Airworthiness Review Certificate (ARC)

Part-M Subpart I defines the airworthiness review process:

The ARC confirms that the aircraft remains in a condition for safe operation

Issued after a review of records and a physical survey

Valid for 1 year (or 3 years for certain non-commercial operations)

Confirms compliance with the approved maintenance programme

4.4 Maintenance Under Part-M Subpart F

Part-M Subpart F allows for maintenance to be performed by:

A Part-145 approved maintenance organisation

A Part-M Subpart F approved maintenance organisation (for non-commercial operations)

The operator's own organisation if it holds a Part-CAMO approval with maintenance privileges

5. Part-21 — Design and Production Requirements

5.1 Purpose and Scope

Part-21 governs the design and production of aircraft, engines, and propellers. It establishes:

Type certification requirements

Production organisation approvals

Airworthiness certificates

Modification and repair approvals

5.2 Classification of Modifications and Repairs

Part-21.A.91 establishes the classification of modifications:

Classification	Definition
Major modification	Has an appreciable effect on weight, balance, structural strength, performance, or other airworthiness characteristics
Minor modification	Does not have an appreciable effect on the above characteristics

Key Point: The classification of a modification as minor or major is the responsibility of the design organisation (or the applicant for a Supplemental Type Certificate). The certifying staff member only verifies that:

The modification is approved

The work is performed per approved data

5.3 EASA Form 1

Part-21.A.307 and Part-M.A.602 define the EASA Form 1 (Authorised Release Certificate):

Confirms that a component has been manufactured or maintained in accordance with approved data

Is required for the installation of components on aircraft

Is not a Certificate of Release to Service for the aircraft itself

6. Minimum Equipment List (MEL) and Defect Deferral

6.1 Purpose of the MEL

The Minimum Equipment List (MEL) is a document developed by the operator, based on the Master Minimum Equipment List (MMEL) issued by the type certificate holder and approved by the competent authority.

The MEL permits the operation of an aircraft with certain equipment inoperative, provided that:

The MEL specifically permits the deferral

The conditions and limitations in the MEL are complied with

The deferral is recorded in the aircraft technical log

6.2 Regulatory Basis for Defect Deferral

Important: Neither Part-145 nor Part-66 imposes a fixed time limit for MEL deferrals. The deferral is governed by:

The MEL's specific conditions and limitations

The operator's maintenance programme

Part-M and Part-CAT operational requirements

> Critical Point: A Part-145 organisation cannot unilaterally defer a maintenance task. Deferral is only possible through the operator's MEL or approved maintenance programme. If a task cannot be completed, the aircraft is not airworthy and a CRS cannot be issued.

7. Certifying Staff Responsibilities

7.1 Scope of Certification

Per Part-66.A.20(a) and Part-145.A.50, the certifying staff member is responsible for:

Ensuring that all maintenance has been performed correctly

Verifying that maintenance was performed in accordance with approved data

Confirming that all required documentation is complete

Ensuring that the aircraft is airworthy before signing the CRS

7.2 Supervision and Oversight

When maintenance is performed by unlicensed mechanics under supervision:

The certifying staff member retains full responsibility for the work

Supervision does not absolve the certifying staff of responsibility

The certifying staff must verify compliance through oversight and documentation review

Verbal reports alone are insufficient — work records must be reviewed

7.3 Prohibited Actions

Certifying staff must never:

Sign for work they have not performed or directly supervised

Issue a CRS for incomplete maintenance

Defer maintenance tasks without proper MEL authorisation

Deviate from approved maintenance data

Certify work outside the scope of their licence privileges

7.4 Shift Handover Procedures

During shift handover:

Incomplete tasks must be clearly documented

The certifying staff member signing the CRS must have performed or supervised the work

A previous mechanic's sign-off does not constitute certification

The original certifier must complete the Return to Service (RTS) certification

8. Operational Regulations (Part-CAT)

8.1 Relationship to Maintenance

Part-CAT (Annex IV to Regulation (EU) No 965/2012) establishes operational requirements for commercial air transport. It interacts with maintenance regulations in several ways:

The operator must have an approved maintenance programme

The operator must use Part-145 organisations for maintenance

The operator must maintain a technical log

MEL usage is governed by Part-CAT requirements

8.2 Third Country Operator (TCO) Authorisation

For aircraft registered in non-EASA countries but operated by EU air operators:

Part-145 organisations may maintain these aircraft under contract

The CRS is issued under Part-145.A.50

The certifying staff member uses their Part-66 licence to certify the work

Part-66 licences are recognised for aircraft maintained in Part-145 organisations, regardless of registration

9. Summary of Key Regulatory References

Topic	Primary Reference
Licence categories and privileges	Part-66.A.20, Appendix I
Licence eligibility	Part-66.A.25, Part-66.A.30
Recent experience	Part-66.A.20(b), Part-66.B.100
Type ratings	Part-66.A.45
Maintenance organisation approval	Part-145.A.30, Part-145.A.35
Certification of maintenance	Part-145.A.50
Approved maintenance data	Part-145.A.45
Continuing airworthiness	Part-M.A.301, Part-M.A.305
Airworthiness review	Part-M Subpart I
Modification classification	Part-21.A.91
Component release	Part-21.A.307, Part-M.A.602

10. Typical Exam Focus Points

10.1 Licence Privileges and Limitations

B1.3 covers mechanical and electrical systems, not avionics (B2)

B1.3 is specifically for helicopter turbine aircraft

Type ratings are required for certification on type-rated aircraft

Non-type-rated engines allow certification of minor scheduled maintenance

10.2 Eligibility and Validity

Minimum age: 18 years

Experience: 3 years (2 years with Part-147 training)

Recent experience: 6 months in preceding 2 years

Licence is issued without expiry date, but privileges require recent experience

Gap of more than 2 years requires refresher training and examination

10.3 Certification Responsibilities

Certifying staff are responsible for all maintenance, including work by supervised mechanics

CRS can only be issued after all required maintenance is complete

Verbal reports are insufficient — documentation must be reviewed

Deferral is only possible through MEL, not unilateral decision

10.4 Regulatory Relationships

Part-66 licences personnel; Part-145 approves organisations; Part-M manages continuing airworthiness

EASA Form 1 is for components, not aircraft

Modification classification is the design organisation's responsibility

MEL deferrals are governed by the MEL, not by Part-66 or Part-145

10.5 Common Examination Traps

Confusing licence validity with privilege validity

Assuming Part-145 can defer maintenance without MEL authorisation

Believing supervision absolves certifying staff of responsibility

Thinking type ratings are not required for type-rated aircraft

Confusing EASA Form 1 with CRS

Assuming experience alone satisfies type rating requirements

11. Conclusion

The regulatory framework for B1.3 certifying staff is built upon a clear hierarchy of regulations, with Part-66 governing personnel licensing, Part-145 governing maintenance organisations, and Part-M governing continuing airworthiness. Understanding the relationships between these regulations, and the specific responsibilities they place on certifying staff, is essential for safe and compliant maintenance practice.

The key principle to remember is that certifying staff are personally responsible for the airworthiness of the aircraft they certify. This responsibility cannot be delegated, transferred, or avoided through supervision arrangements. The licence is the legal authority to certify, but the knowledge, skill, and integrity of the individual certifying staff member are what ensure the safety of the aviation system.

Module 10: Aviation Legislation