Explanatory Statement
Civil Aviation Safety Regulations 1998
AD/ENG/5 Amdt 10 — Turbine Engine Continuing Airworthiness Requirements
Legislation
Under section 98 of the Civil Aviation Act 1988 (the Act), the Governor-General may make regulations for the purpose of carrying out and giving effect to the provisions of the Convention on International Civil Aviation relating to safety, amongst other things. Under regulation 39.001 of the Civil Aviation Safety Regulations 1998 (CASR), the Civil Aviation Safety Authority (CASA) may issue an airworthiness directive (AD) for a kind of aircraft or aeronautical product. Under subsections 98 (5B) and (5BA) of the Act, an AD is a legislative instrument unless it is expressed to apply in relation to a particular person, a particular aircraft or a particular aeronautical product.
Subsection 98 (5D) of the Act provides that a legislative instrument made under the Act or the regulations may apply, adopt or incorporate any matter contained in any instrument or other writing as in force or existing from time to time, even if the other instrument or writing does not yet exist when the legislative instrument is made.
Under subsection 33 (3) of the Acts Interpretation Act 1901, where an Act confers a power to make, grant or issue any instrument of a legislative or administrative character (including rules, regulations or by-laws), the power shall be construed as including a power exercisable in the like manner and subject to the like conditions (if any) to repeal, rescind, revoke, amend, or vary any such instrument.
Under Annex 8 to the Convention on International Civil Aviation, the State of Design has overall responsibility for continuing airworthiness of an aircraft type, and must provide any information necessary to ensure the continuing airworthiness of a type to appropriate States of Registry. ADs (and their equivalents) are the most common form of continuing airworthiness information, and are issued by most International Civil Aviation Organization Contracting States.
The State of Registry of an individual aircraft or aeronautical product is responsible for its continuing airworthiness. Under Annex 8, the State of Registry must develop or adopt requirements to ensure the continuing airworthiness of aircraft.
There are many turbine-powered aircraft on the Australian register. CASA issued AD/ENG/5 Amdt 9 in 2004 to correct an unsafe situation on turbine engines in aircraft other than aircraft administered by an approved sports aviation body, aircraft issued with a limited category certificate of airworthiness under regulation 21.189 of the CASR or aircraft issued with an experimental certificate under regulation 21.195A of the CASR. The AD does not apply to these aircraft types as they operate under different maintenance regimes to the aircraft to which the AD applies.
AD/ENG/5 Amdt 9 was issued to require these turbine engines to be overhauled or inspected at specified intervals. As Pratt and Whitney Canada have cancelled a Service Information Letter (SIL PT6A-122) which was referenced in AD/ENG/5 Amdt 9, CASA has issued AD/ENG/5 Amdt 10 to remove references to SIL PT6A-122 and replace them with references to the latest version of SIL No. GEN-055 existing at commencement of this AD amendment, that is, PWC SIL No. GEN-055 R10 dated 13 November 2018. The opportunity has also been taken to more clearly describe the manufacturer’s documents to be referred to for the overhaul and inspection of specified models of engines.
Also, the AD amendment states that previously issued Alternative Means of Compliances (AMOCs) or Exclusions to AD.ENG/5 Amdt 9 are considered acceptable for compliance with the equivalent requirements of this AD. CASA has taken this approach of recognising previously granted approvals of alternate means of compliance, and exclusions, under subregulation 39.004(2) of CASR, for the purposes of compliance with, or exclusion from, the equivalent requirements of this Amendment because the requirements have not changed substantively and will assist stakeholders.
This AD repeals and replaces the previous AD on this subject.
Documents Incorporated by Reference
Under subsection 14 (2) of the Legislation Act 2003 (the LA), unless the contrary intention appears, a legislative instrument may not incorporate any matter contained in an instrument or other writing as existing from time to time. Subsection 98 (5D) of the Act provides that, despite section 14 of the LA, a legislative instrument made under the Act or the regulations may apply, adopt or incorporate any matter contained in any instrument or other writing as in force or existing from time to time.
In accordance with paragraph 15J(2)(c) of the LA, the following table contains a description of the documents incorporated by reference into the legislative instrument, the organisation responsible for each document and how they may be obtained. The table also states how the document is incorporated.
Document | Description | Source |
Pratt & Whitney Canada Service Information Letter SIL No. GEN-055 Revision 10 (R10), Guidelines and Standards for Subscribing and Utilizing the Internet-based Engine Condition Trend Monitoring EHM Services, dated 13 November 2018, as existing at the commencement of the instrument | Contains information about conducting an Engine Condition Trend Monitoring (ECTM) program. | Can be purchased from the engine manufacturer (original equipment manufacturer (OEM)) by subscription.
Operators have access from the Pratt & Whitney customer portal at https://www.prattwhitney.com
Also available for viewing at CASA offices by prior arrangement as described below. |
Each Honeywell Service Bulletin (SB) that applies to a specified model of Honeywell TPE331 series engine, as the SB exists from time to time
| Contains inspections and overhaul requirements, including time between overhaul (TBO), or Continuous Airworthiness Maintenance Operation (CAM) programs for specified models of Honeywell TPE331 engines.
(CAM programs are published by Honeywell in SBs.) | Can be purchased from the OEM by subscription.
Operators have access from the Honeywell customer portal at https://aerospace.honeywell.com
Also available for viewing at CASA offices by prior arrangement as described below. |
Each Pratt and Whitney Canada Service Bulletin (SB) that applies to a model of PW&C PT6A series engine, as the SB exists from time to time
| Contains inspections and overhauls requirements, including time between overhaul (TBO), for specified models of Pratt & Whitney PT6A engines.
| Can be purchased from the OEM by subscription.
Operators have access from the Pratt & Whitney customer portal at https://www.prattwhitney.com
Also available for viewing at CASA offices by prior arrangement as described below |
System of maintenance for the aircraft approved under regulation 42M of CAR, as it exists from time to time | Matters to be included in a system of maintenance are set out in regulation 42L of CAR. These include a schedule that sets out the regulator maintenance inspections tests and checks to be carried out on the aircraft, and when time-lifed components are to be retired, overhauled or removed.
Changes to approved systems of maintenance must be approved by CASA (see regulation 42T of CAR). | The aircraft operator.
Also available for viewing at CASA offices by prior arrangement. |
SBs are incorporated for the purposes of maintenance of an engine model if they apply to the engine model. For example, Honeywell SB TPE331-72-0180 Revision 42 provides inspections and overhaul requirements, specifically TBO or CAM, for Honeywell TPE331-10 and -11 series engines. Similarly, P&WC SB PT6A-72-1303 Revision 15 provides a recommended basic operating TBO and a recommended initial Hot Section Inspection (HSI) frequency specifically for P&WC PT6A-34AG series engines.
The Honeywell and Patt & Whitney Canada documents incorporated into this AD are not freely available as they are proprietary, copyright, documents of a technical nature, prepared on a commercial basis. They can be purchased from the relevant OEM by subscription.
As a matter of practicality, it would not be possible for aircraft operators to operate aircraft in Australian and foreign airspace without having their own subscription access to relevant technical documents of the aircraft and engine manufacturer. Nevertheless, as a current subscriber for the documents, CASA will make the relevant sections of the incorporated technical documents available, in its Canberra or other offices, by arrangement, and, in keeping with the proprietary nature of the documents, for viewing only, to any aircraft operator who is affected by the instrument, or to any interested person. In the unlikely event that it is required, CASA may also provide advice to interested persons regarding the applicable SB for an engine model.
Consultation
Given the relatively minor nature of the changes made by this AD, CASA undertook targeted consultation on the AD with a limited number of stakeholders, providing the proposed AD (PAD) to Regional Airline Association of Australia (RAAA and Aerial Application Association of Australia (AAAA) for consultation with their membership.
CASA is satisfied that no further consultation is appropriate or reasonably practicable for this instrument for section 17 of the LA.
Sector risk, economic and cost impact
Subsection 9A (1) of the Act states that, in exercising its powers and performing its functions, CASA must regard the safety of air navigation as the most important consideration. Subsection 9A (3) of the Act states that, subject to subsection (1), in developing and promulgating aviation safety standards under paragraph 9 (1) (c), CASA must:
(a) consider the economic and cost impact on individuals, businesses and the community of the standards; and
(b) take into account the differing risks associated with different industry sectors.
The cost impact of a standard refers to the direct cost (in the sense of price or expense) which a standard would cause individuals, businesses and the community to incur. The economic impact of a standard refers to the impact a standard would have on the production, distribution and use of wealth across the economy, at the level of the individual, relevant businesses in the aviation sector, and the community more broadly. The economic impact of a standard could also include the general financial impact of that standard on different industry sectors.
The economic and cost impact of the instrument has been determined by:
(a) the identification of individuals and businesses affected by the instrument;
(b) consideration of how the requirements to be imposed on individuals and businesses under the instrument will be different compared to existing requirements;
(c) a valuation of the impact, in terms of direct costs on individuals and businesses affected by the instrument to comply with the different requirements. This valuation is consistent with the principles of best practice regulation of the Australian Government.
CASA has assessed that the economic and cost impact of the instrument is not significant. The requirements of the instrument apply to holders of certificates of registration of relevant aircraft. The instrument will reduce cost to owners of pre-1966 manufactured aircraft.
Impact on categories of operations
The instrument is likely to have a negligible effect on operations conducted by the relevant aircraft because it clarifies maintenance requirements.
Impact on regional and remote communities
The instrument will not have a negative impact on regional and remote communities and may reduce the maintenance costs of individuals and businesses operating aircraft in those communities.
Office of Impact Analysis (OIA)
An Impact Analysis (IA) is not required because ADs are covered by a carve out by the Office of Impact Analysis under which an IA is not required for Australian or foreign airworthiness directives (OIA23-06244).
Sunsetting
As an instrument relating to aviation safety made under CASR, Part 4 of Chapter 3 of the Legislation Act 2003 (sunsetting of legislative instruments) does not apply to this instrument (item 15 of the table in section 12 of the Legislation (Exemptions and Other Matters) Regulation 2015). The instrument requires that the action set out in the instrument, that relates to aircraft or aeronautical products, be taken to correct an unsafe condition. As such, the instrument is intended to have enduring operation and it would not be appropriate for it to be subject to sunsetting.
Statement of Compatibility with Human Rights
A Statement of Compatibility with Human Rights is at Attachment 1.
Making and commencement
The instrument has been made by a delegate of CASA relying on the power of delegation under subregulation 11.260 (1) of CASR and subsection 94 (1) of the Act.
The instrument commences on 31 March 2026.
Attachment 1
Statement of Compatibility with Human Rights
Prepared in accordance with Part 3 of the
Human Rights (Parliamentary Scrutiny) Act 2011
AD/ENG/5 Amdt 10 – Turbine Engine Continuing Airworthiness Requirements
This legislative instrument is compatible with the human rights and freedoms recognised or declared in the international instruments listed in section 3 of the Human Rights (Parliamentary Scrutiny) Act 2011.
Overview of the legislative instrument
CASA issued AD/ENG/5 Amdt 9 in 2004 to correct an unsafe situation relating to turbine engines on certain aircraft. There are many turbine-powered aircraft on the Australian register, and CASA developed this AD to ensure that turbine engines on the aircraft to which the AD applies are overhauled or inspected at specified intervals. As Pratt and Whitney Canada have cancelled a document (SIL PT6A-122) which was referenced in AD/ENG/5 Amdt 9, CASA has issued AD/ENG/5 Amdt 10 to replace the reference to service information letter SIL PT6A-122 with a reference to SIL No. GEN-055 (R10). The instrument also updates the descriptions of other maintenance documents that are incorporated by reference in the instrument and includes a statement regarding recognition of alternate means of compliance and exclusions previously granted by CASA.
This AD repeals and replaces the previous AD on this subject. The primary purpose of this legislative instrument is to ensure that turbine engines of aircraft are overhauled or inspected at specified intervals.
Human rights implications
This legislative instrument does not engage any of the applicable rights or freedoms.
Conclusion
This legislative instrument is compatible with human rights as it does not raise any human rights issues.
Civil Aviation Safety Authority