Browse Topic: Aircraft certification
Advanced air mobility (AAM) seeks to develop a large-scale transportation system to revolutionize how people live and work, with electric vertical take-off and landing (eVTOL) aircraft serving a central role due to reduced emissions and noise impact. An important aspect for eVTOL aircraft certification is safe urban operations, which require understanding of the response due to aerodynamic disturbances. Experimental data are required to support eVTOL aircraft development with respect to flight dynamics and controllability, as well as design specification development. While flight testing of the full-sized air vehicle will be necessary as part of the certification process, subscale testing offers many advantages with respect to cost and flexibility, in addition to examining operational conditions that one would be reluctant to test in flight at full scale such as emergency conditions. These advantages only may be seen if the underlying scaling principles of flight dynamics / control, aerodynamic interactions, and propulsion-airframe integration are understood. This paper describes initial work towards development of a general subscale testing methodology for eVTOL aircraft flight dynamics and disturbance response characteristics including limited degree of freedom (DOF) and free flight testing. An overview of the initial development work is provided, including discussion of scaling relationships, subscale air vehicle model development, and testing activities focusing on flying qualities and stability / control characteristics.
The aerospace industry is undergoing a profound transformation driven by emerging aviation technologies, including Advanced Air Mobility (AAM), electric vertical takeoff and landing (eVTOL) aircraft, and highly automated flight control systems. These complex systems often feature tightly coupled flight controls and power plants where traditional methods of compliance — relying heavily on physical ground and flight testing — are becoming increasingly impractical due to the vast number of potential interaction cases. To address this challenge, the SAE G-35 Modeling, Simulation, and Training for Emerging Aviation Technologies and Concepts Committee was formed to develop industry consensus standards. This presentation discusses the landmark release of SAE ARP7094, "Recommended Practice for Using Modeling and Simulation for Certification of Aircraft, Products, and Systems" and its role in establishing a standardized, simulation-based path to certification. The SAE G35C group is responsible for developing standards and procedures for using modeling and simulation as a method of compliance for the certification of AAM aircraft similar to the RCbS project conducted in collaboration between EASA, academia and industry in Europe.
This paper outlines observations from an FAA-sponsored research project that examined aviation Fly-By-Wire (FBW) accidents. The goal was to identify risk areas that will help guide a focus for FAA certification testing. Part of this study specifically focused on current powered-lift tiltrotors, identifying six general categories of causal factors for accidents, which will be discussed in detail regarding how they influenced flight control designs. The results of this survey, along with extrapolation to current designs, will be discussed and will illustrate why manufacturers are moving toward state-based flight control designs. In a state-based flight control scheme, the pilot does not have direct control over aircraft attitudes and motor tilt angles. Instead, the pilot requests a speed and or flight path with inceptor input, and the commanded attitudes and motor tilts are scheduled by the flight control computer. Additionally, recent lessons learned from electric Vertical Takeoff and Landing (eVTOL) aircraft accidents will be discussed, along with a comparison of powered-lift causal factors to accidents in the transport category FBW fixed-wing aircraft. From this analysis, broad observations will be offered about the trend of how accident-causal factors may evolve with greater maturity in aircraft design. This accident survey will be detailed further as part of an upcoming FAA Research Report.
In the last years, new rotorcraft configurations have increased the attention among industries, through which the tiltrotor one due to its capability of combining both rotorcraft and aircraft advantages. However, there are situations where the vertical take-off mode could be enhanced in hard environmental and flight conditions. Therefore, to address this challenge, this work aims to develop a methodology to characterize a roll take-off model for a general tiltrotor configuration in such situations. By combining the integration of the equation of motion and geometrical assumptions, the runway distance is determined for an acceptable range of nacelle tilting angles. The process is developed by meeting the requirements defined by the regulations, combining the aircraft certification standards (CS23 and CS25) with the available tiltrotor certification basis from the FAA project #TC3419RC-R. Following the Nominal application, a sensitivity analysis is carried out, which studies the main effects on the results by varying one variable at a time in terms of weight, wing-loading, and disk-loading.
Aircraft Certification is a mature and complex bureaucracy that has successfully ensured a very high degree of safety of aircraft design, construction, operation and maintenance. Outside of a very few doing the work, there is a general lack of knowledge of certification details. For novel technologies such as electric power, and innovative configurations such as multi-rotors, the rules are far less mature and still emerging and so also poorly understood. Within the Advanced Air Mobility (AAM) initiative, many new aircraft developments are underway using novel configurations, and the public announcements of regulatory progress toward FAA or EASA Type Certification capitalize on this ignorance by being vague or even misleading. Honeywell conceived the Regulatory Readiness Level (RRL) indicator as an objective measure of certification status to serve the AAM industry and ecosystem, with applicability across aviation. The released RRL Version 1 now enables credible, objective assessment of new aircraft progress toward FAA Type Certification, and Operational Approval for Part 135 operations, to allow consistent apples-to-apples comparisons with other aircraft in development. An emerging complementary version of the rubric for EASA Type Certification is ready for publication to enable RRL determination against the European Union criteria. Future releases will consider other Nation's regulatory authorities, supplemental types certifications (STCs), and risk-based airworthiness assessments such as the Specific Operations Risk Assessments (SORA).
Airworthiness certification of aircraft requires an Airworthiness Security Process (AWSP) to ensure safe operation under potential unauthorized interactions, particularly in the context of growing cyber threats. Regulatory authorities mandate the consideration of Intentional Unauthorized Electronic Interactions (IUEI) in the development of aircraft, airborne software, and equipment. As the industry increasingly adopts Model-Based Systems Engineering (MBSE) to accelerate development, we aim to enhance this effort by focusing on security scope definitions – a critical step within the AWSP for security risk assessment that establishes the boundaries and extent of security measures. However, our findings indicate that, despite the increasing use of model-based tools in development, these security scope definitions often remain either document-based or, when modeled, are presented at overly abstract levels, both of which limit their utility. Furthermore, we found that these definitions frequently lack alignment with airworthiness security regulations. To address these two distinct gaps, this paper presents a model-based approach for detailed security scope definitions using the Systems Modelling Language (SysML). Our approach aligns with airworthiness security regulations ED-202A / DO-326A and ED-203A / DO-356A and incorporates a SysML profile based on the CORAS language for accurate modeling of security scopes. This facilitates a model-based security risk assessment by creating unambiguously system models that represent assets through model elements, document entry points to the assets and determine their environment. This SysML-based approach supports certification related activities by ensuring that security scope definitions are comprehensive and aligned with airworthiness regulations, directly addressing the identified gaps. The approach's applicability and effectiveness are demonstrated through an illustrative example in the domain of aircraft cabin system development. Moreover, the approach provides valuable inputs that assist operators in deriving guidance for the safe operation and maintenance of the aircraft, complementing existing methods and practices.
In the domain of aircraft certification, Development Assurance is what some would call a useful tool to gain confidence in the development of complex systems, and what others would call a necessary evil. But what does it actually do? Why is it necessary for certification of modern aircraft? What, epistemologically, does it bring to the table? This paper aims to show how Development Assurance (DA) activities, at all levels from aircraft to item, close the epistemological holes created when complex systems are chosen for implementation. It will map the different sources and types of uncertainty encountered in system and aircraft verification and explain how each type is dealt with within a certification context, working from simple mechanical systems up to complex and highly integrated systems using software and airborne electronic hardware and beyond. It will show that Development Assurance, far from being an arbitrary set of activities, systematically brings personal and corporate expertise to bear to provide confidence that development errors have been sufficiently identified and mitigated or eliminated.
Headquartered in San Juan, Puerto Rico, Unusual Machines describes itself as a “classic American technology company born from garage tinkerers and hobbyists, focused on serving the emerging drone industry with unique and innovative products.” The company recently launched a new low-cost flight controller for drones, the Riot Brave F7, that achieved “Blue UAS” certification from the Department of Defense's (DoD) Defense Innovation Unit (DIU) in August. The Riot Brave F7 - just $58 - features a STMF722RET6 processor equipped with Bosch accelerometer and barometer, and has 16Mb of built in Blackbox Memory. While the company developed Riot Brave F7 primarily as a low cost flight controller option for FPV drones, there are broader possibilities for it, including military applications.
Aircraft Certification is a mature and complex bureaucracy that has successfully ensured a very high degree of safety of aircraft design, construction, operation and maintenance. Outside of a very few professionals doing the work, there is a general lack of knowledge of certification details. For novel technologies such as electric power, and for innovative configurations such as distributed lift and lift-plus-lift-cruise, the rules are far less mature and still emerging and so also poorly understood. Within the Advanced Air Mobility (AAM) initiative, many new aircraft developments are underway using novel configurations, and the public announcements of regulatory progress toward FAA or EASA Type Certification capitalize on this unfamiliarity by being vague or even misleading. Honeywell conceived the Regulatory Readiness Level (RRL) indicator as an objective measure of certification status to serve the AAM industry and ecosystem, with applicability across all of aviation. RRL Version 1 enables a credible, objective assessment of new aircraft progress toward FAA Type Certification, and Operational Approval for Part 135 operations, to allow consistent apples-to-apples comparisons with other aircraft in development. Future RRL releases with allow determination of progress against criteria from EASA and other regulatory authorities, for supplemental types certifications STCs), and for risk-based airworthiness assessments such as EASA Specific Operations Risk Assessments (SORA).
The extent of automation and autonomy used in general aviation (GA) has been steadily increasing for decades, with the pace of development accelerating recently. This has huge potential benefits for safety given that it is estimated that 75% of the accidents in personal and on-demand GA are due to pilot error. However, an approach to certifying autonomous systems that relies on reversionary modes limits their potential to improve safety. Placing a human pilot in a situation where they are suddenly tasked with flying an airplane in a failed situation, often without sufficient situational awareness, is overly demanding. This consideration, coupled with advancing technology that may not align with a deterministic certification paradigm, creates an opportunity for new approaches to certifying autonomous and highly automated aircraft systems. The new paths must account for the multifaceted aviation approach to risk management which has interlocking requirements for airworthiness and operations (including training and airspace integration). They occur across a variety of different operational paradigms with varying roles for the human and the systems in question. If implemented properly, autonomy can take GA safety to the next level while simultaneously increasing the number and variety of aircraft and transportation options they provide.
Additive manufacturing (AM) is currently being used to produce many aerospace components, with its inherent design flexibility enabling an array of unique and novel possibilities. But, in order to grow the application space of polymer AM, the industry has to provide an offering with improved mechanical properties. Several entities are working toward introducing continuous fibers embedded into either a thermoplastic or thermoset resin system. This approach can enable significant improvement in mechanical properties and could be what is needed to open new and exciting applications within the aerospace industry. However, as the technology begins to mature, there are a couple of unsettled issues that are beginning to come to light. The most common question raised is whether composite AM can achieve the performance of traditional composite manufacturing. If AM cannot reach this level, is there enough application potential to warrant the development investment? The answers are highly dependent on the individual processors and will require significant research. Yet, there are still other common challenges that are not isolated to a singular processor. The focuses of this chapter are the capability to design and provide robust structural analysis for continuous fiber-reinforced polymer AM—two unsung aspects that can make or break this new technology as it finds its way into the aerospace market. These two unsettled issues, out of many, may require fundamental changes to the design, analysis, and manufacturing process. Without solutions to them, adoption by the aerospace industry will be limited to point design applications, thus constraining the technology to being nothing more than a specialized tool.
As model-based systems engineering is proliferating throughout the aerospace industry as a method to manage the development of complex cyber-physical systems, opportunities to leverage formal methods for verification and validation purposes are significant. As a system model described in SysML can contain the level of semantics required to define strict system requirements, it is possible to create a translation tool to generate SRL (SADL (Semantic Application Design Language) Requirements Language) to leverage ASSERT™ (Analysis of Semantic Specifications and Efficient generation of requirements-based Tests) for verification and validation of the system requirements. SADL [13] is a controlled English grammar that translates directly into OWL (Web Ontology Language) [14]. As part of the validation of the SRL requirements, ASSERT™ leverages a theorem prover to look for conflict and completeness errors. For verification, ASSERT™ uses a Satisfiability Modulo Theories (SMT) solver for the generation of test cases and procedures. This paper extends the Braking System Control Unit (BSCU) portion of the Wheel Braking System (WBS) example within Appendix E of ARP4754B [2] described in [1] to demonstrate an example of capturing system requirements in Cameo using SysML, creating test cases and procedures from ASSERT™ exporting from SysML and translating to SRL/SADL, and exporting the Cameo system model data along with the test cases, test procedures, and requirements analysis data from ASSERT™ into the Rapid Assurance Curation Kit (RACK). RACK is a data curation platform which facilitates reporting on Development Assurance and safety assessments guidelines like those used for aircraft certification.
Advanced flight control system, aviation battery and motor technologies are driving the rapid development of eVTOL to offer possibilities for Urban Air Mobility. The safety and airworthiness of eVTOL aircraft and systems are the critical issues to be considered in eVTOL design process. Regarding to the flight control system, its complexity of design and interfaces with other airborne systems require detailed safety assessment through the development process. Based on SAE ARP4754A, a forward architecture design process with comprehensive safety assessment is introduced to achieve complete safety and hazard analysis. The new features of flight control system for eVTOL are described to start function capture and architecture design. Model-based system engineering method is applied to establish the functional architecture in a traceable way. SFHA and STPA methods are applied in a complementary way to identify the potential safety risk caused by failure and unsafe control action. PSSA with FTA assists to allocate safety requirements and modify the architecture of flight control system. Through the practice of safety-oriented architecture design of flight control system for eVTOL, safety requirements are identified, and related modifications and design are implemented to optimize the system architecture design. Comparing to the safety assessment method with only ARP4761 methods, the combination of ARP4761 and STPA will extend the perspective to deal with potential unsafety issues. Hazards caused by random failure and incorrected control are all tackled. The work of this paper can serve as a useful reference for the system safety assessment and architecture design for eVTOL and airborne systems.
In an application first, the physics of why the sky is blue is used to measure gas flows without obstructive sensors. A longstanding industry partnership between Virginia Polytechnic Institute and State University (Virginia Tech) and Pratt & Whitney has resulted in a new laser-optical technology that aims to revolutionize in-flight thrust measurement.
This SAE Aerospace Standard (AS) provides general design and test requirements for a flat cut-off pressure compensated, variable delivery hydraulic pump for use in a civil aircraft hydraulic system with a rated system pressure up to 5000 psi (34500 kPa). NOTE: Hydraulic pumps may incorporate features such as a clutch in the input drive, which will not be covered by this standard.
This document contains minimum operational performance specification (MOPS) of active on-board INFLIGHT ICING DETECTION SYSTEMS (FIDS). This MOPS specifies FIDS operational performance which is the minimum necessary to satisfy regulatory requirements for the design and manufacture of the equipment to a minimum standard and guidance towards acceptable means of compliance when installed on an AIRCRAFT. Detection of ICE accreted on the AIRCRAFT during ground operations is not considered in this document. This MOPS was written for the use of FIDS on AIRCRAFT as defined in 1.3 and 2.3. Expected minimum performance specifications for FIDS and their functions are provided in Section 3. The minimum performance requirements as defined in Section 3 do not consider SYSTEM performance as installed on the AIRCRAFT. Performance in excess of the minimum performance may be required by the SYSTEM installed on an AIRCRAFT in order to meet regulatory or operational requirements. This topic is considered in Section 6. This MOPS document is structured as follows: Operational performance specifications for functions or COMPONENTS that refer to equipment capabilities that exceed the stated minimum requirements are identified as optional features. The word “equipment” as used in this document includes all COMPONENTS and units necessary for the SYSTEM to properly perform its intended function(s). For example, the “equipment” may include all of the COMPONENTS listed in 1.4. It should not be inferred that each FIDS design will necessarily include all of the COMPONENTS or units listed in that Section. This will depend on the specific design chosen by the FIDS manufacturer.
The advent of electrified propulsion in the aerospace sector, captured in microcosm by the fast-emerging eVTOL market, both threatens to upset the establishment of major aerospace players and offers significant new opportunities for start-up companies. In all cases, it is forcing a marriage of system simulation and architecture definition techniques from markets already meeting these challenges, such as automotive. The demands of these aerospace applications are causing engineers on both sides to find the best blend of tools and approaches to meet their goals.
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