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- Unmanned aerial vehicle safety assessment modelling through petri NetsPublication . Gonçalves, P.; Sobral, José; Ferreira, L. A.Currently we are facing an increasing trend of use of Unmanned Aerial Vehicles (UAV) in various activities both civilian and military. Although there is no legal framework for the operation of these systems, regulatory authorities require the demonstration of a safety level equivalent to manned aircraft. It is known the high vulnerability of the UAV not only to unexpected failures of their systems but also to the environment. The purpose of this paper is to present a safety assessment process modelling of a UAV by Petri Nets, that can be accepted by certifying bodies, considering the recommendations of STANAG 4671 UAV Airworthiness Requirements Specification (USAR) for analysis of fault conditions that lead to the most feared events. It is intended to show through the use of Petri Nets the frequency that the UAV enters the identified states described as most feared events; the ability of the UAV to react after being in a fault situation to the inputs of the operating crew in order to enhance trust and to facilitate the operation authorization process in UAV operations. The results obtained allowed to identify and to define critical areas and corrective actions that will lead to an acceptable level of risk for the regulatory authority.
- Development of unmanned aerial vehicles maintenance strategy under an asset management frameworkPublication . Gonçalves, P.; Sobral, José; Ferreira, L. A.Many organizations in a large number of countries all around the world are now awaking for a new reality concerning potential applications for the usage of unmanned aerial vehicles (UAV) or unmanned aerial systems (UAS). What was initially strictly applied for military purposes or pure private entertainment has now widespread for other purposes as for example for book or pizza delivery to customers. In manned commercial and military aircraft the MSG (Maintenance Steering Group) philosophy is usually followed and is the root of all inspection schedules in a process starting before an aircraft enters service. However, for the UAV (or UAS), as a system, there are not yet such procedures and each operator establishes the needed requirements on the development stage. The question is how to integrate this type of equipment in an asset management framework as presented in the PAS 55 or the recent ISO 55000. The objective of this paper is to show an exemple of the development of a UAV where these issues are discussed and some proposals to integrate them on an asset management framework regarding the design for effectiveness and design for safety are made on an early stage of an asset engineering process.