3.1 To promote safe flight through aircraft design, some National Airworthiness Authorities and Military Airworthiness Authorities (NAAs/MAAs) prescribe airworthiness design requirements. Prescribed airworthiness design requirements are usually documented in an Airworthiness Code (DASR 21 refers) and represent a complete and consistent set of requirements that define those attributes of aircraft systems, or functions, that underpin safe flight.
3.2 As discussed in Section 1 Chapter 1 of this manual, it is not practical for Defence to create and maintain its own Airworthiness Code. Consequently, the Authority has recognised a number of civil and military Airworthiness Codes as providing a sound foundation for the safe design of Defence aircraft.
3.3 This chapter of the DASDRM:
describes the application of Airworthiness Codes
identifies and describes the Authority recognised Airworthiness Codes
describes the approach adopted by the Authority to establishing the acceptability of aircraft designs not developed to an Authority recognised Airworthiness Code.
3.4 Uncrewed aircraft systems (UAS). The approach adopted by the Authority to prescribing UAS airworthiness design requirements is described separately in Section 4 of this manual.
3.5 An aircraft developed to an Authority recognised Airworthiness Code should substantially meet the level of safety expected by Defence. While the Authority might prescribe additional design requirements to address known deficiencies in the Airworthiness Code, or to encompass Defence’s unique Configuration, Role and operating Environment (CRE), these are not normally substantial additions.
3.6 This section describes the Authority’s approach to recognising Airworthiness Codes, and for identifying where supplementation to a Code is needed.
3.7 For the Authority to recognise an Airworthiness Code, as a minimum, the Code must:
be prescribed by a recognised NAA/MAA
have demonstrated a sound safety record
prescribe a complete and consistent suite of airworthiness design requirements
be supported by associated guidance on how to achieve compliance with the airworthiness design requirements
be accessible, ie published by the NAA/MAA in a consolidated and easily accessed format.
3.8 Where an Airworthiness Code is recognised by the Authority, unless otherwise stated in this manual the recognition automatically refers to the current version of the Code. Earlier versions of an Airworthiness Code may be acceptable to the Authority provided the changes between the earlier version and the current version have been analysed and the effect on safety characterised. Project Offices seeking to acquire Defence aircraft designed to an earlier version of a recognised Airworthiness Code are to petition the Authority for a decision on the acceptability of the earlier version.
3.9 As mentioned previously, an aircraft developed to an Authority recognised Airworthiness Code should substantially meet the level of safety expected by Defence. However, for a particular aircraft acquisition, the Authority would normally prescribe supplementary airworthiness design requirements, as a result of:
known inadequacies in the Airworthiness Code
novel features included in the proposed design that are not accommodated by the Code
proposed Defence-unique roles and/or operating environments that are outside the scope of the Code, and/or
Defence policies or Australian legislated requirements not being covered by the Code.
3.10 Sections 2 and 3 of this manual present airworthiness design requirements that are commonly needed to supplement Airworthiness Codes. Where supplementation is not commonly required, a corresponding chapter has not been included in this manual. Regardless, the Authority may identify specific areas for deeper evaluation on a case-by-case basis for an aircraft acquisition or design change, and prescribe design requirements in addition to Sections 2 and 3 where warranted.
3.11 The previous section presented the criteria employed by the Authority for recognising Airworthiness Codes. This section identifies and defines those civil and military Airworthiness Codes that have been recognised by the Authority as providing a sound foundation for the safe design of Defence aircraft.
3.12 The United States of America Federal Aviation Administration (FAA) is an Authority recognised civil NAA. The FAA prescribes airworthiness design requirements (commonly referred to as the Federal Aviation Regulations (FARs)) to assure safe aircraft design in the Code of Federal Regulations Title 14 (CFR 14) Aeronautics and Space, Chapter 1 Federal Aviation Administration, Department of Transportation, sub-Chapter C, Aircraft. Sub-Chapter C is further separated into Parts that prescribe specific airworthiness design requirements for an aircraft category or aircraft engines.
3.13 Not all of the airworthiness design requirements prescribed in the FAR Parts under sub-Chapter C are applicable to Defence aircraft. Consequently, the Authority has recognised an Airworthiness Code based on the airworthiness design requirements prescribed by the FAA in the following FAR Parts:
Part 2311 – Airworthiness standards: Normal, utility, acrobatic and commuter category airplanes
Part 25 – Airworthiness standards: Transport category airplanes
Part 26 – Continued airworthiness and safety improvements for transport category airplanes
Part 27 – Airworthiness standards: Normal category rotorcraft
Part 29 – Airworthiness standards: Transport category rotorcraft
Part 33 – Airworthiness standards: Aircraft engines
Part 35 – Airworthiness standards: Propellers.
3.14 The FAA also prescribes minimum equipment and/or systems requirements in sub-Chapter D, Airmen, and sub-Chapter G, Air Carriers and Operators for Compensation or Hire: Certification and Operations, of CFR 14 Chapter 1 for specified operations, and these equipment/system requirements inherently levy airworthiness design requirements. The applicability and suitability, for Defence aircraft, of the airworthiness design requirements levied in the following FAR Parts will be established following determination of the type of operations to be undertaken by the Defence aircraft and the airspace in which these operations will occur:
Part 91 – General Operating and Flight Rules
Part 121 – Operating Requirements: Domestic, Flag and Supplemental Operations
Part 135 – Operating Requirements: Commuter and On-demand Operations and Rules Governing Persons On Board Such Aircraft.
3.15 Accordingly, from Defence’s perspective, the FAA’s Airworthiness Code effectively consists of airworthiness design requirements from FAR Parts 23, 25, 26, 27, 29, 33 and 35, and those airworthiness design requirements inherently levied by FAR Parts 91, 121 and 135 that are relevant to Defence’s proposed operations. This Airworthiness Code is accepted by the Authority as providing an acceptable foundation for the safe design of Defence aircraft. Further detail on the application of FAA prescribed airworthiness design requirements for particular aircraft types, technologies and systems, and operations is contained in the relevant chapters in Sections 2 and 3 of this manual.
3.16 The European Aviation Safety Agency (EASA) is the NAA responsible for conducting civil aircraft Type Certification on behalf of the countries of the European Union. EASA prescribes airworthiness design requirements within Certification Specifications (CSs) promulgated under the authority of Regulation (EC) No 216/2008 of 20/02/2008, Basic Regulation, and Commission Regulation (EU) No 748/2012 of 03/08/2012, Initial Airworthiness. EASA CSs are harmonised with the FAA FAR Parts with respect to aircraft Type Certification. Consequently, EASA CS-23, -25, -27, -29, -E and -P prescribe substantially the same requirements as those within the equivalent FAR Parts.
3.17 Not all of the airworthiness design requirements prescribed in EASA CSs are applicable to Defence aircraft. Consequently, the Authority has recognised an Airworthiness Code based on the airworthiness design requirements prescribed by EASA in the following CSs:
CS-2322 – Normal, Utility, Aerobatic and Commuter Aeroplanes
CS-25 – Large Aeroplanes
CS-26 – Continued airworthiness and safety improvements for transport category airplanes
CS-27 – Small Rotorcraft
CS-29 – Large Rotorcraft
CS-E – Engines
CS-P – Propellers.
3.18 EASA also prescribes minimum systems and/or equipment requirements for specified operations in CSs, and these requirements inherently levy airworthiness design requirements. Further, EASA has issued operational regulations under European Commission Regulation (EU) No 965/2012, which prescribes technical requirements and administrative procedures related to air operations. These requirements inherently levy airworthiness design requirements through the specification of minimum systems and equipment necessary for specified operations in European airspace. The applicability and suitability, for Defence aircraft, of the airworthiness design requirements inherently levied in the following EASA CSs and EU regulations will be established following determination of the type of operations to be undertaken by the Defence aircraft and the airspace in which these operations will occur:
CS-ACNS – Airborne Communications, Navigation and Surveillance
CS-AWO – All Weather Operations
Regulation (EU) 965/2012 Annex IV Commercial Air Transport, Subpart D Instruments, Data and Equipment CAT.IDE.A (Aeroplanes) and CAT.IDE.H (Helicopters)
Regulation (EU) 965/2012 Annex V Specific Approvals.
3.19 Accordingly, from Defence’s perspective, EASA’s Airworthiness Code effectively consists of airworthiness design requirements from CS-23, -25, -26, -27, -29, -E and -P, and those requirements levied by operational CSs and EU regulations that are relevant to proposed Defence operations. This Airworthiness Code is recognised by the Authority as providing an acceptable foundation for the safe design of Defence aircraft. Further detail on the application of EASA prescribed airworthiness design requirements for particular aircraft types, technologies and systems, and operations is contained in the relevant chapters in Sections 2 and 3 of this manual.
3.20 The Civil Aviation Safety Authority (CASA) of Australia is an Authority recognised civil NAA. CASA prescribes airworthiness design requirements in the Civil Aviation Safety Regulations (CASRs). CASA’s approach to prescribing airworthiness design requirements is to leverage extensively off those requirements prescribed in the associated FARs and CSs. For example, CASR Part 23 identifies ‘the airworthiness standards for an aeroplane in the normal category, utility category, acrobatic category or commuter category’ as those prescribed by the FAA and EASA in FAR Part 23, CS-VLA and CS-23 (with any changes identified by CASA in CASR Part 23).
3.21 The Authority has recognised an Airworthiness Code based on the airworthiness design requirements prescribed by CASA in the following CASRs:
CASR Part 2333 – Airworthiness standards for aeroplanes in the normal, utility, acrobatic or commuter category
CASR Part 25 – Airworthiness standards for aeroplanes in the transport category
CASR Part 27 – Airworthiness standards for rotorcraft in the normal category
CASR Part 29 – Airworthiness standards for rotorcraft in the transport category
CASR Part 33 – Airworthiness standards for aircraft engines
CASR Part 35 – Airworthiness standards for aircraft propellers.
3.22 While CASA leverages extensively off the airworthiness design requirements prescribed by the FAA and EASA, CASA also prescribes minimum systems and/or equipment requirements for particular operations in CASR operational regulations and Civil Aviation Orders (CAOs), and these requirements inherently levy airworthiness design requirements. The applicability and suitability, for Defence aircraft, of the airworthiness design requirements levied in the following CASRs and CAOs will be established following determination of the type of operations to be undertaken by the Defence aircraft and the airspace in which these operations will occur:
CASR Part 91 – General and Operating Flight Rules (and associated Manual of Standards)
CASR Part 121 – Australian Air Transport Operations-Larger Aeroplanes (and associated Manual of Standards)
CAO Part 20 – Air Service Operations
CAO Part 82 – Air Operators Certificates.
3.23 Accordingly, from Defence’s perspective, CASA’s Airworthiness Code effectively consists of airworthiness design requirements from CASR 23, 25, 27, 29, 33 and 35, and those requirements levied by CASR Parts 91and 121, and CAOs, that are relevant to proposed Defence operations. This Airworthiness Code is recognised by the Authority as providing an acceptable foundation for the safe design of Defence aircraft. Further detail on the application of CASA prescribed airworthiness design requirements for particular aircraft types, technologies and systems, and operations is contained in the relevant chapters in Sections 2 and 3 of this manual.
3.24 The United State Air Force (USAF), US Navy and US Army are MAAs recognised by the Authority. The US DoD airworthiness design requirements are published in military handbook MIL-HDBK-516C, Airworthiness Certification Criteria. This document follows a ‘systems’ based approach (rather than aircraft type), with references to applicable airworthiness criteria, design standards, means of compliance and tailoring for different aircraft types where required.
3.25 The airworthiness design requirements prescribed in MIL-HDBK-516C are recognised by the Authority as providing an acceptable foundation for the safe design of Defence aircraft. Importantly, previous versions of MIL-HDBK-516 (with the exception of MIL-HDBK-516B (Expanded Version)) are not MAA Airworthiness Codes recognised by the Authority. Only MIL-HDBK-516C (and MIL-HDBK-516B (Expanded Version)) prescribes airworthiness design requirements in a manner that satisfies the criteria for Airworthiness Code recognition described in paragraph 3.7. Note that MIL-HDBK-516C is intended to be tailored to prescribe airworthiness design requirements for specific aircraft types and roles.
3.26 The United Kingdom Ministry of Defence (UK MoD) is an Authority recognised MAA. The UK MoD prescribes airworthiness design requirements in Defence Standard DEF-STAN 00-970, Design and Airworthiness Requirements for Service Aircraft. DEF-STAN 00-970 is divided into a number of Parts that prescribe airworthiness design requirements for specific aircraft types and ancillary equipment categories as follows:
a. Part 1 – Combat Aeroplanes
b. Part 3 – Small Type Aeroplanes
c. Part 5 – Large Type Aeroplanes
d. Part 7 – Rotorcraft
e. Part 11 – Engines.
3.27 The airworthiness design requirements prescribed in the UK MoD Airworthiness Code defined in paragraph 3.26 are recognised by the Authority as providing an acceptable foundation for the safe design of Defence aircraft. However, like the US DoD Airworthiness Code, the UK MoD Code is intended to be tailored to prescribe airworthiness design requirements for specific aircraft types and roles.
3.28 Occasionally, Defence will procure aircraft that were not developed to an Authority recognised Airworthiness Code. In these circumstances, the Authority will determine whether the airworthiness design requirements applied to the aircraft design provide an acceptable foundation for the safe design of Defence aircraft. There are two situations where such an assessment may be required:
the aircraft design has been developed using an Airworthiness Code that has not yet been recognised by the Authority, or
the aircraft design has been developed to satisfy a bespoke suite of airworthiness design requirements.
3.29 Each of these situations is discussed in the following paragraphs.
3.30 Where Defence proposes to procure an aircraft design that has been developed using an Airworthiness Code (either civil or military) that is not recognised by the Authority, the Authority will evaluate the Airworthiness Code to determine if it satisfies the criteria for Authority recognition at paragraph 3.7. Alternatively, the Authority will evaluate the airworthiness design requirements prescribed for the original aircraft design using the approach described in paragraphs 3.31 and 3.32 below. In either case, the design requirement supplementation described at paragraphs 3.9 and 3.10 is likely to be applicable.
Aircraft designed to a bespoke suite of airworthiness design requirements
3.31 Defence may acquire aircraft that have been ‘type certified’ by Authority recognised MAAs (eg US Army, US Navy and French DGA), where the suite of airworthiness design requirements used to support this certification do not satisfy one or more of the criteria at paragraph 3.7 for Authority recognition as an Airworthiness Code. For example:
The US Army has prescribed airworthiness design requirements in ADS-51-HDBK US Army Rotorcraft and Aircraft Qualification Handbook. However, ADS-51-HDBK does not satisfy the criteria at paragraph 3.7.c for an Airworthiness Code to prescribe a comprehensive suite of airworthiness design requirements.
While the US Navy may adopt MIL-HDBK-516C when establishing the certification criteria for a particular aircraft design, the US Navy does not currently present these criteria in a consolidated Type Certification Basis (TCB) (which is a fundamental requirement of MIL-HDBK-516C)44. In essence, the US Navy defines a bespoke ‘Airworthiness Code’ for each aircraft certification program, but does not promulgate the Code in a manner that satisfies the criteria at paragraph 3.7.e regarding Airworthiness Code consolidation and ease of access.
3.32 While the Authority does not classify these sets of airworthiness design requirements as Airworthiness Codes, they may still be approved by the Authority on an individual basis (through approving the Defence aircraft TCB) as providing a suitable foundation for the safe design of a Defence aircraft. This might be achieved through comparison to a recognised Airworthiness Code, or by another method determined by the Authority. Regardless, the design requirements supplementation described at paragraphs 3.9 and 3.10 is likely to be equally applicable.
3.33 Regardless of whether an aircraft design conforms to an Authority recognised Airworthiness Code or not, any major design changes to Defence aircraft must satisfy the airworthiness design requirements prescribed in the approved aircraft TCB as a minimum. Where appropriate, more recent versions of airworthiness design requirements should be evaluated to determine whether compliance with the later version would contribute materially to the level of safety afforded by the design and would be practicable to implement. The determination of whether compliance with a later amendment to the applicable airworthiness design requirements is warranted, is conducted using the criteria defined in DASR 21.A.91, DASR 21.A.97 and DASR 21.A.101. Section 1 Chapter 2 Annex A provides further guidance on the application of earlier versions of Airworthiness Codes to major design changes.
3.34 The Authority prescribed airworthiness design requirements in this manual are not intended to be applied to in-service aircraft that are not undergoing modification (ie retrospective application). Where the Authority determines that retrospective application of an airworthiness design requirement is warranted, this will be promulgated via separate direction.