Search Results (148)

One approach to make the aviation sector climate-compatible is to minimize greenhouse gas emissions by employing electric and hybrid electric propulsion system concepts. The introduction of novel technologies introduces novel failure modes and consequently effects of failure conditions on the aircraft. This study examines the safety of distributed electrified aircraft propulsion systems and evaluates individual failure scenarios in the context of the relevant certification requirements. A comparison of the functional architectures of legacy and Electric Hybrid Propulsion Systems (EHPSs) is conducted and the existing aircraft-level requirements, that are based on experience with conventional propulsion systems, are assessed for their applicability to the certification of novel propulsion systems. Subsequently the relevant safety items from these requirements are identified in the context of a critical loss of thrust scenario. Analysis methods are assigned to these safety items in order to prove the compliance of the novel systems with the legacy certification documentation. This results in a validation concept for EHPS at the aircraft level in the context of a critical loss of thrust. In particular, the distribution of individual subsystems and components throughout the aircraft leads to reduced isolation of the respective propulsion systems and thus potential safety-critical interactions with adjacent systems. The analysis demonstrates that the use of distributed propulsion systems increases the risk of multiple failures of redundant systems and cascading failure propagation, highlighting the need to develop targeted means of prevention and the mitigation of failure conditions for these systems. Full article

Artificial Intelligence (AI) is emerging as a transformative enabler in aviation, with applications spanning Guidance, Navigation and Control (GNC), Air Traffic Management (ATM), and predictive maintenance. However, the adoption of AI in safety-critical domains remains constrained by the absence of established certification guidance. Traditional standards such as Aerospace Recommended Practice (ARP), ARP4754B, ARP4761A, DO-178C, and DO-254 assume deterministic behaviour and verifiable logic, whereas AI exhibits adaptive and non-deterministic characteristics. Regulatory initiatives, including the European Union Artificial Intelligence Act, the European Union Aviation Safety Agency (EASA) AI Roadmap 2.0, the Federal Aviation Administration (FAA) AI Safety Assurance Roadmap, and ISO/IEC Technical Report (TR) 5469:2024, signal progress but remain fragmented, exploratory, and often limited to low-level autonomous use cases. This study adopts a qualitative approach combining literature and standards analysis with expert interviews to identify gaps in post-deployment assurance, data governance, explainability, and accountability. A conceptual life cycle-oriented framework is proposed that embeds AI-specific assurance activities such as dataset validation, iterative verification, drift detection, and retraining oversight into established certification processes. The framework extends classical and emerging verification and validation models into operational service, linking machine learning constituents to system-level safety arguments and regulatory expectations to support the development of trustworthy and certifiable AI-enabled aviation systems. Full article

The importance of system safety elevates with the introduction of novel technologies in the aviation industry. With the rise of system complexity, regular safety practices include iterative workflows and heavy reliance on expert knowledge. For the development of modern, efficient aircraft systems, there is a need for innovative approaches. This paper presents a tool, OSIRIS (operational safety and integrated risk analysis), that supports safety and risk analyses utilizing artificial intelligence (AI) concepts. Developed as a key safety feature within the HADES modeling framework, OSIRIS aligns with an architecture-based design approach for abstract system modeling, adhering to model-based systems engineering (MBSE) principles and standards. It currently aids safety engineers in formulating system failure cases consistent with functional hazard assessments (FHA), representing model-based safety assessment (MBSA) in compliance with SAE ARP4761A. The methodological concepts and their implementation in OSIRIS are demonstrated considering an abstract system model from aeronautical applications. The generated results were evaluated against the system context to confirm compliance with the FHA process required for certification. Further, the future work will explore refining OSIRIS’s capabilities and its application cases. Full article

Aircraft design is regulated by federal law and must comply with complex regulatory documentation. The complexity of the certification process has resulted in a growing interest in digital transformation, for which models are often used to provide explicit structure. Ontological modeling is one of the most promising approaches for the digital transformation of regulatory documentation. This paper presents a novel approach to ontology development that applies ontology design patterns to construct a knowledge representation of regulatory documentation, with a focus on guidance material. The approach includes five main processes: (i) the selection of a regulatory document; (ii) the use of a natural language processing tool; (iii) a contextual analysis; (iv) the identification of patterns in the natural language; and (v) the development and implementation of ontology design patterns. The modeling approach is demonstrated using the ARP4754B: Guidelines for Development of Civil Aircraft and Systems guidance material document and is validated with a use case AC21.101-1B—Establishing the Certification Basis of Changed Aeronautical Products guidance material document. The modeling approach is then verified against an established set of regulatory documentation modeling requirements. The systematic ontological modeling approach presented in this paper enables digital transformation of regulatory documentation, a necessary step for a more efficient and effective certification process. Full article

The electrification of future aircraft poses significant challenges to existing electrical power system (EPS) architectures, particularly due to increasing installed power levels, the introduction of electric flight control, and the (partial) electrification of propulsion systems. The transition to AEA requires more than simply replacing conventional systems with electrical counterparts. It demands a fundamental redesign of the electrical system architecture. This study investigates three novel EPS architectures for More Electric Aircraft (MEA) and three corresponding ones for All Electric Aircraft (AEA). All concepts are based on the segmentation of the EPS into electrically isolated microgrids and the separation between propulsion and on-board systems, aiming to improve system reliability, efficiency, fault management, and certification flexibility. The disruptive architecture proposes islanded microgrids, where electrical loads are grouped by Design Assurance Level (DAL) and spatial distribution. Each microgrid is powered locally by batteries, which significantly reduces cabling mass, electromagnetic interference (EMI), and system complexity. By decoupling safety-critical from non-critical loads and reducing reliance on centralized distribution, the proposed architectures increase reliability and reduce complexity. Full article

Studying the effect of gusts on aircraft is an essential task in aerodynamic and structural design and analysis, as well as in airworthiness certification. The singular design and operational characteristics of Remotely Piloted Aircraft (RPA) demand a specific study of gust effects on these vehicles. This investigation uses the discrete gust criterion prescribed in current fixed-wing RPA codes to analyse the gust behaviour of RPA from a conceptual design viewpoint. The results obtained from the flight envelope analysis allow us to assess the influence of stall, manoeuvring, and gust effects on the overall envelope, with these aspects showing significant differences with respect to conventionally piloted aircraft. Full article

The aviation industry is transitioning toward hydrogen propulsion to meet sustainability goals, introducing novel fire safety risks that require updated regulatory frameworks. This study addresses the certification challenges for liquid hydrogen fuel systems by advancing the Certification Readiness Level through a model-driven approach. Using a Model-Based Safety Assessment, this research applies Bow-Tie Diagrams within the NASA AdvoCATE software to analyze in-flight fire risks for a tube-and-wing aircraft architecture. The study models critical threats, including cryogenic embrittlement and leakage, mapping them to specific prevention and protection barriers derived from a regulatory gap analysis. The assessment identifies leakage as the primary failure condition and proposes a safety architecture that emphasizes prevention barriers. Quantitative safety case modeling demonstrates, with proposed means of mitigation and barrier integrity, the feasibility to compute the residual probability of a catastrophic in-flight fire according to EASA CS 25.1309 requirements. These findings validate the use of safety architectures to bridge the gap between design and rulemaking, offering a scalable framework to support early-stage certification and the safe integration of hydrogen technologies into commercial aviation. Full article

This study presents a flight-envelope-based methodology for aerodynamic load assessment and composite material selection applied to a hybrid fixed-wing tri-rotor VTOL (Vertical Take-Off and Landing) unmanned aerial vehicle (UAV). A certification-oriented maneuver and gust envelope was established to define the critical load cases. Reynolds-averaged Navier–Stokes (RANS) simulations of the full aircraft at nominal cruise were performed to determine global aerodynamic coefficients and distributed pressure fields, including interference effects from the fuselage and externally mounted VTOL system. A complementary wing-only angle-of-attack study was used to characterize lift, drag, and chordwise pressure distributions over the relevant incidence range. Critical envelope points were mapped to equivalent aerodynamic states in terms of lift coefficient and angle of attack, enabling a quasi-steady correlation between certification loads and CFD (Computational Fluid Dynamics) results. In parallel, carbon fiber-reinforced polymer (CFRP) laminates were experimentally evaluated under tensile, open-hole tensile, and flexural loading. The results indicate that, within the two investigated laminate configurations, the [0°/90°] CFRP laminate provides the more suitable strength and stiffness for primary wing structures, while off-axis laminates are better suited for secondary regions. The proposed workflow links flight-envelope definition, aerodynamic analysis, and material selection, providing a basis for preliminary structural design. Full article

The study of aircraft gust behaviour is essential in aerodynamic and structural design and analysis, as well as in airworthiness certification. The particularities of fixed-wing Remotely Piloted Aircraft (RPA) demand a specific study of gust effects on these vehicles and their implications in RPA design and operation. The research presented here addresses the investigation of gust behaviour of RPA within the frame of conceptual design through three complementary approaches, which are respectively based on the assessment of gust and manoeuvring envelopes of RPA, the modelisation of multi-mission flight profiles of RPA towards the evaluation of the variations in gust load factor along the mission, and the analysis of the interaction of RPA conceptual design parameters with gust behaviour. These approaches are applied to various case studies, providing several key insights into the gust behaviour characteristics of RPA. These include the assessment of the operational conditions in which gust-induced stall may occur and the way in which they interact with typical mission conditions of RPA, the evaluation of the impact of mission parameters in RPA gust response along with the capability of identifying the most critical gust load factor condition for the set of considered design missions, and the ways in which undesirable gust effects may be mitigated in the conceptual design stage through the change in overall RPA design parameters. Full article

This article evaluates two model-based systems engineering (MBSE) toolchains that support aircraft certification under EASA CS-23 Amendment 6. Airworthiness requirements and associated acceptable means of compliance are digitalized as Systems Modeling Language (SysML) models that preserve document structure and encode parameters and expressions needed for substantiation. The maneuvering and gust flight envelope required by CS-23 Subpart C is used as a representative case to compare workflow integration, robustness, and artifact generation. One implementation combines Eclipse Papyrus with MATLAB to export and parse the SysML model and to execute automated calculations and reporting. The second uses CATIA Magic Systems of Systems Architect (MSoSA) to export stereotype fields to JSON and to run C++ routines orchestrated by activity diagrams. Both toolchains generate certification-relevant outputs, including design airspeeds, limit load factors, and flight envelope plots, while improving traceability relative to document-centric practice. The comparison indicates that the Papyrus/MATLAB approach supports rapid prototyping but is more sensitive to regulatory text changes, whereas the MSoSA-based approach reduces dependence on text–pattern parsing and provides more integrated execution. These results suggest that MBSE can improve the efficiency of preparing certification evidence, with adoption trade-offs driven by licensing cost, integration effort, and organizational maturity. Full article

With the rapid development of electric Vertical Take-Off and Landing (eVTOL) aircraft for urban air mobility, ensuring safe operation in complex low-altitude environments remains a major challenge. In particular, interactions with non-cooperative airspace users introduce uncertainties that are difficult to fully handle with current autonomous systems. To better understand these risks, a Monte Carlo simulation framework is developed to model random encounters between an eVTOL and uncontrolled unmanned aerial vehicles. The results show a relatively low collision probability of approximately 0.18%. However, a large proportion of encounters fall within an intermediate separation range of 100–200 m, indicating a high-frequency conflict region that still requires continuous monitoring and decision-making. Based on these observations, Fault Tree Analysis (FTA) is further applied to evaluate system-level safety under different operational architectures, incorporating revised assumptions on human reliability and system interactions. The results suggest that the inclusion of human pilots can contribute to reducing the probability of catastrophic failure compared with fully autonomous configurations, particularly in uncertain and non-cooperative scenarios. These findings suggest that, although full autonomy is a long-term goal, current intelligent systems still face limitations in dealing with uncertain and non-cooperative scenarios in urban airspace. In such situations, human operators can provide additional situational awareness and flexible decision-making, improving overall system robustness. Overall, a phased transition toward full autonomy, starting from a human–machine collaborative approach, appears to be a practical path to ensure safety, support certification, and enable the deployment of eVTOL systems. Full article

Emergency locator transmitters (ELTs) are key safety systems for post-crash aircraft localization and search-and-rescue operations. In more electric aircraft (MEA), however, their design and operation are increasingly influenced by complex electrical architectures, tighter equipment integration, and more demanding electromagnetic environments. This paper presents a narrative literature review of ELT technology from a MEA-oriented perspective. A practice-oriented narrative approach is adopted, examining ELTs through a dual lens: the evolution of the search and rescue (SAR) ecosystem and the progressive electrification of aircraft systems. The review addresses ELT fundamentals, classifications, operating principles, and interaction with the Cospas-Sarsat infrastructure, and examines the transition from legacy analog beacons to modern 406 MHz digital systems incorporating GNSS positioning, MEOSAR capabilities, second-generation beacon functionalities, and distress tracking features. Particular attention is given to integration challenges in MEA platforms, including autonomous energy supply, battery endurance, power quality disturbances, electromagnetic compatibility, installation robustness, antenna survivability, and certification constraints. The analysis highlights that ELT performance in MEA depends not only on the beacon itself, but also on the coupled interaction among device design, installation conditions, and the electrical environment. Finally, the review outlines research priorities for next-generation ELTs, including improved survivability assessment, energy-aware architectures, integration strategies based on electromagnetic compatibility, and certification-ready solutions compatible with future aircraft platforms. Full article

Liquid hydrogen (LH₂) as an energy source is viewed as a potential path to achieve carbon neutral commercial aviation, albeit accompanied by a plethora of structural, thermal and safety challenges that still need to be resolved. With respect to a LH₂ tank’s structural integration aspect, static, damage tolerance and impact/crashworthiness responses need to be investigated. Ιn the present work, an efficient structural integration concept of LH₂ tanks into a Regional Commercial Aircraft fuselage is proposed, analyzed and preliminary designed, as part of the Clean Aviation project HERFUSE. The main purpose of the work is the feasibility assessment of introducing adhesively bonded solutions in the connection of LH₂ tanks to the aircraft fuselage. The initial design of the potential mounting system configuration was investigated via a finite element parametric simulation model that was developed for this purpose and used to analyze different variations in the proposed concept, under certification relevant load cases. Different variations in the mounting system were assessed, considering their effect on the stress concentrations developed in the fuselage and the tank structure, as well as induced deformations and potential joints debonding. The results indicated that the utilization of adhesive bonding elements in the design of an LH₂ tank integration system is conceptually efficient, although the specific configuration-related shortcomings that were identified need to be tackled. As far as the preliminary design study results are concerned, the minimum required number of joining elements were identified and an initial mass prediction of the mounting system was performed to be used as initial value in the entire hybrid–electric novel aircraft design loop. Future studies on the detailed design and sizing of the mounting system, as well as to incorporate dynamic crash analyses and implementation of energy absorbing elements are needed. Full article

The increasing availability of onboard sensors and digital monitoring platforms has enabled the continuous acquisition of operational and health-related data in aircraft systems. In parallel, advances in Big Data analytics and Artificial Intelligence (AI) have driven significant progress in Predictive Maintenance (PdM), enabling earlier fault detection and more reliable estimations of Remaining Useful Life (RUL). This systematic literature review examines recent developments in AI-driven PdM and fault detection applied to aircraft over the last years. A total of 20 studies were selected based on predefined inclusion criteria and analyzed with respect to research trends, application domains, algorithmic approaches, and expected outputs. The findings indicate a strong research emphasis on civil aviation supported by accessible operational datasets, whereas military aviation research prioritizes fleet readiness and mission continuity, often with limited data transparency. Deep learning approaches, particularly hybrid models combining convolutional and recurrent architectures, dominate recent prognostic methodologies, while optimization and Model-Based Systems Engineering (MBSE) frameworks support decision-making integration. Despite these advancements, the transition from experimental models to operational deployment remains constrained by data heterogeneity, model explainability requirements, and regulatory certification processes. This review highlights current progress and identifies gaps and research opportunities to accelerate the adoption of robust and scalable PdM solutions in aviation. Full article

The cloud spatial uniformity in the test section is crucial for icing wind tunnels in aircraft icing research and airworthiness certification. To achieve uniform supercooled large droplet (SLD) icing conditions, both the spatial variation in droplet size distribution and the concentration should be considered. In this study, the spatial distribution of droplets under three SLD conditions is explored in the Aviation Industry Corporation of China Aerodynamics Research Institute (AVICARI)’s FL-61 icing wind tunnel. Measurements are conducted at 12 test points in vertical and horizontal directions using the holographic airborne cloud particle imager (HACPI) in conjunction with a two-axis traversing system. The droplet images obtained at specific test points below the test section centerline show deformation phenomena for droplets larger than 400 $\mathsf{\mu }$m. Additionally, the aspect ratio of deformed droplets increases with droplet size. The spatial evolution of the median volume diameter (MVD) and liquid water content (LWC) is examined. For two spray arrangements where the activated nozzles are positioned close, the test point where the LWC peak in the vertical direction occurs is higher than that of the MVD peak. Further analysis focuses on the size distribution of droplets in the vertical direction. The results show that the settling effect of the droplets larger than 50 $\mathsf{\mu }$m is evident under a flow velocity of 78 m/s. Meanwhile, the position where large droplets tend to appear lowers as the droplet size increases. Finally, the spatial uniformity of droplet size distributions at the same radial distance is discussed. Full article