ARP4754B (Systems Development)

An SAE Aerospace Recommended Practice that provides guidelines for the development of civil aircraft and systems, considering the overall aircraft operating environment and functions. ARP4754B defines the aircraft and system development process, including planning, requirements capture, design, implementation, integration, verification, validation, configuration management, quality assurance, and certification liaison. It establishes the framework for assigning Development Assurance Levels (DALs) to functions, systems, and items based on failure condition severity, and describes the integral processes (safety assessment, requirements management, validation) that support development assurance.

An SAE Aerospace Recommended Practice that provides guidelines for the development of aircraft and aircraft systems, taking into account the overall aircraft operating environment and functions. ARP4754B describes a development assurance process that includes safety assessment, requirements validation, implementation verification, and configuration management. It is widely referenced by FAA and EASA as an accepted means for showing compliance with system-level development assurance requirements.

The EUROCAE publication of the systems development assurance guidance that is technically aligned with SAE ARP4754B. ED-79B provides guidelines for the development of civil aircraft and systems, addressing the same topics as ARP4754B: system development processes, development assurance level assignment, safety assessment integration, validation, verification, and configuration management. ED-79B is referenced by EASA in AMC 20-152A.

The complete set of airworthiness requirements (regulations at specific amendment levels), special conditions, exemptions, and equivalent safety findings that an applicant must comply with to obtain a design approval. The certification basis is established by the certifying authority early in the certification project and is documented formally. For a new TC, the certification basis is determined by the applicable regulations in effect on the date of the TC application, plus any later amendments elected by the applicant or required by the authority.

A program-level document prepared by the applicant and agreed with the certifying authority that describes the overall strategy, schedule, and approach for completing the certification project. The certification plan typically includes a description of the product and proposed changes, the certification basis, the means of compliance for each requirement area, the organizational structure and responsibilities, the schedule and milestones, the data submittal plan, and any known certification risks or issues. It serves as the project roadmap.

The specification of a hardware or software item that results from the functional allocation and system architecture definition process. Item definition establishes the item's functional requirements, performance requirements, interface requirements, environmental requirements, and design assurance level, forming the starting point for the item-level development process under DO-254 (hardware) or DO-178C (software).

The process of assigning aircraft-level functions to specific systems, and subsequently allocating system functions to hardware items and software components within the system architecture. Functional allocation establishes which physical elements implement each required function and defines the interfaces between them.

The process of assigning Design Assurance Levels to system components based on the failure condition classifications determined during the system safety assessment, and the use of architectural partitioning to limit the propagation of faults between components of different assurance levels. Partitioning enables a lower-DAL component to coexist with a higher-DAL component on the same hardware or in the same system without requiring the lower-DAL component to be developed at the higher level.

Requirements that are generated through the safety assessment process (PSSA, SSA) rather than being directly traceable to a higher-level requirement or regulation. Derived safety requirements emerge from the architecture and implementation decisions made to achieve safety objectives. Examples include requirements for failure monitoring (to detect latent failures), requirements for dissimilarity between redundant channels, independence requirements for power supplies to redundant systems, exposure time limits for maintenance intervals, and requirements for crew annunciation of degraded states.

An Interface Control Document (ICD) formally defines the physical, electrical, logical, and data characteristics of the interface between two or more systems, subsystems, or components. ICDs specify connector types and pin assignments, signal characteristics (voltage levels, timing, protocols), data formats and message definitions, and the responsibilities of each side of the interface.

The formal determination by the certifying authority (or an authorized delegate such as a DER, ODA unit member, or DOA compliance verification engineer) that the applicant's type design meets a specific airworthiness requirement. A compliance finding is the outcome of the authority's evaluation of the applicant's compliance data (reports, test results, analyses). Each regulation in the certification basis requires a positive compliance finding before the certificate can be issued. The aggregate of all compliance findings constitutes the authority's basis for issuing the design approval.

The documents prepared by the applicant (or the applicant's suppliers) that present the evidence of compliance with specific airworthiness requirements. Compliance reports summarize the analysis, test, or inspection activities performed, the methodology used, the results obtained, and the conclusion regarding compliance. Test reports document the setup, procedures, results, and conclusions of specific tests. Analysis reports document analytical methods, assumptions, inputs, calculations, and conclusions. These reports constitute the substantiation data that the authority evaluates when making compliance findings.