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Airworthiness certification of commercial transport aircraft requires a safety analysis of the propulsion system to establish that the probability of a failure jeopardising the safety of the aeroplane is acceptably low. The needs and desired features of such a propulsion system safety analysis are discussed, and current techniques and assumptions employed in such analyses are evaluated. It is concluded that current assumptions and techniques are not well suited to predicting behaviour of the propulsion system in service. The propulsion accident history of the high bypass ratio commercial transport fleet is reviewed and an alternate approach to propulsion system safety analysis is developed, based on this accident history. Features of the alternate approach include quantified prediction of propulsion related crew error, engine-level reliability growth modelling to realistically predict engine failure rates, and quantified credit for design features which mitigate the effects of propulsion system failures. The alternate approach is validated by applying it to two existing propulsion systems. It is found to produce forecasts in good agreement with service experience. Use of the alternate approach to propulsion system safety analysis during design and development will enable accurate prediction of the expected propulsion related accident rate and identification of opportunities to reduce the accident rate by incorporating mitigating features into the propulsion system/aeroplane design.

Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / Dissertation presented in fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering at Stellenbosch University. / ENGLISH ABSTRACT: Airworthiness certification of unmanned aircraft systems (UAS) is normally considered to be a regulatory function. In the absence of comprehensive UAS airworthiness regulations, the development of new and unique UAS, and their introduction into non-segregated airspace, remain major challenges for the UAS industry and regulators. Thus, in response, the objective of this research was to establish a framework and guidelines, within the scope of the typical regulatory regime, that can be used by the UAS engineering domain to ensure the safe and reliable functioning of a UAS, whether regulated or not. UAS airworthiness is currently mainly based on manned aircraft regulations, and the focus is on the unmanned aircraft and the 'airworthiness' of the remote control station. The typical UAS as a system, however, consists of more than just these elements and a broader approach to the 'airworthiness' of a UAS is required. This study investigated and introduces the concept of UAS operability, where the term 'operability' addresses the safe and reliable functioning of the UAS as a system, the airworthiness of its airborne sub-systems, and the safe and reliable functioning of its non-airborne subsystems and functional payloads. To ensure that the results of this study are aligned with typical aviation regulatory systems, a regulatory basis was defined within which UAS operability guidelines could be developed. Based on the operability concept, and in the scope of the regulatory basis, a UAS operability framework was developed for the UAS engineering domain. This framework is an index and reference source from which appropriate operability elements can be selected for a particular UAS. The scope of the framework is generic, rather than UAS-type or -class specific, and includes operability elements for the UAS as a system, for its airborne and non-airborne sub-systems, and for its payloads. The framework was validated by developing lower hierarchical levels for the framework and by populating each operability element of the framework with appropriate engineering guidance criteria. The guidance criteria were derived and/or developed from industry 'best practices' found in the literature, or were newly developed where no existing practices were found. The significance of this study is found in its establishing of a generic UAS operability framework that not only focuses on the airworthiness of the unmanned aircraft, but addresses the operability of the UAS as a system, as well as the operability of its airborne sub-systems, its non-airborne sub-systems and its payloads. In practice, the UAS operability framework can be used in the UAS engineering domain as an index and reference source to select relevant operability elements for a particular UAS. The guidance criteria for the selected elements can subsequently be used to develop the appropriate processes, procedures, requirements and specifications to achieve initial operability of the UAS, and to maintain its continued operability. Although the objective of the research was achieved, the UAS operability framework must still be applied and tested in real-life UAS projects and, where necessary, revised to eliminate shortcomings and to provide for new and novel developments in UAS engineering technologies. / AFRIKAANSE OPSOMMING: Die lugwaardigheidsertifisering van onbemande vliegtuigstelsels (OVS) word normaalweg beskou as 'n reguleringsfunksie. In die afwesigheid van omvattende OVS lugwaardigheidsregulasies bly die ontwikkeling van nuwe en unieke OVS, en die inbedryfstelling daarvan in onafgesonderde lugruim, besonderse uitdagings vir beide die OVS nywerheid en reguleerders. Die doelwit van hierdie navorsing was dus om riglyne binne die bestek van die tipiese reguleringsregime te vestig wat deur die OVS ingenieursdomein benut kan word om die veilige en betroubare funksionering van 'n OVS te verseker, of dit gereguleer word aldan nie. OVS lugwaardigheid word tans hoofsaaklik gebaseer op lugwaardigheidsvereistes vir bemande vliegtuie. Die fokus is dan ook meerendeels op die onbemande vliegtuig en die 'lugwaardigheid' van die afstandbeheerstasie. Die tipiese OVS bestaan egter uit meer sub-stelsels en 'n weier beskouing van die 'lugwaardigheid' van 'n OVS is nodig. Die konsep van OVS bedryfbaarheid is in hierdie studie ondersoek en voorgestel. 'Bedryfbaarheid' beteken in hierdie konteks die veilige en betroubare funksionering van die OVS as 'n stelsel, die lugwaardigheid van die lug sub-stelsels, die veilige en betroubare funksionering van die nie-lug sub-stelsels, asook die veilige en betroubare funksionering van funksionele loonvragte. Om te verseker dat die resultate van hierdie studie versoenbaar is met tipiese lugvaart reguleringstelsels, is 'n reguleringsbasis omskryf vir die ontwikkeling van OVS bedryfbaarheidsriglyne. Gebaseer op die bedryfbaarheidskonsep, en binne die riglyne van die reguleringsbasis, is 'n OVS bedryfbaarheidsraamwerk ontwikkel vir die OVS ingenieursdomein. Die raamwerk is 'n indeks en verwysingsbron waaruit gepaste bedryfbaarheids-elemente gekies kan word vir 'n bepaalde OVS. Die bestek van die raamwerk is generies en nie beperk tot spesifieke OVS tipes of klasse nie. Die raamwerk sluit bedryfbaarheidselemente in vir die OVS as stelsel, asook vir die lug en nie-lug sub-stelsels van die OVS, en vir die loonvragte van die OVS. Die raamwerk se geldigheid was bevestig deur die struktuur van die raamwerk tot laer vlakke uit te brei en gepaste ingenieursriglyne vir elke bedryfbaarheids-element in die raamwerk te ontwikkel. Die riglyne was gebaseer op 'beste praktyke' soos beskryf in die literatuur, of was van nuuts af ontwikkel waar geen bestaande praktyke gevind kon word nie. Die bydrae van hierdie studie is gesetel in die vestiging van 'n generiese OVS bedryfbaarheidsraamwerk wat nie net gemik is op die lugwaardigheid van die onbemande vliegtuig nie, maar wat die bedryfbaarheid in geheel van die OVS as stelsel aanspreek, asook die bedryfbaarheid van die OVS se lug sub-stelsels, nie-lug sub-stelsels en loonvragte. In die praktyk kan die raamwerk in die OVS ingenieursdomein gebruik word om gepaste bedryfbaarheids-elemente vir 'n OVS te kies. Daarna kan die bedryfbaarheidsriglyne gebruik word om gepaste prosesse, prosedures, vereistes en spesifikasies te ontwikkel om die OVS se aanvanklike en voortgesette bedryfbaarheid te bewerkstellig. Alhoewel die doelwit vir die navorsing bereik is, moet die OVS bedryfbaarheidsraamwerk nog op werklike OVS projekte getoets word. Waar nodig, moet die raamwerk dan hersien word om tekortkominge, asook nuwe en unieke ontwikkelinge in OVS ingenieurstegnologie, aan te spreek.

The air transport markets affected by global economic climate and regional demand characteristics are evolving fairly dynamically. To cope with the evolving demand and to penetrate desired market segments, operators' usage of aircraft has been getting more and more dynamic with increased deviation from the originally designed mission objectives. The objective of this research is to investigate the effects of in-service rrusslon variation on aircraft structural performance so as to provide airlines with a more realistic approach toward better fleet management. During the research, the scenarios and phenomena causing fleet in-service mission variations were investigated. A survey on the utilisation of world-wide aircraft fleets was conducted and presented. The in-service missions of aircraft fleets were found to vary significantly in terms of mission profile. Furthermore, the utilisation patterns of individual aircraft in the same fleet of a major airline are also being thoroughly analysed. Tremendous variations of mission mixes are found among individual aircraft. In order to analyse the effects of the in-service mission variation, methodologies and models based on fatigue test results have been developed by the author. Actual service data are being input for the effect analysis. It is found that the mission variation has a considerable engineering influence on the aircraft's structural performance either in terms of mission airworthiness or fatigue life span. Finally, a conceptual model, the 'Integrated Airline Fleet Management Model' (IAFM), has been developed as a blueprint for practical application. By implementing the IAFM, airline will be able to obtain a realistic picture of the health of its aircraft. With a more reliable basis for maintenance planning, improved inspection accuracy, reduced maintenance cost and better structural airworthiness can be achieved.

No description available.

<p>Westhelicopter INC. has an aviation workshop providing qualified helicopter maintenance in accordance with PART-145. Maintenance and administrative base is situated in Luleå at Kallax airport. <strong>The types that Westhelicopter INC are currently authorised to service are: </strong>Eurocopter AS 350 Base/Line Maintenance, Eurocopter EC 120 Base/Line Maintenance and Robinsson R44 Base/Line Maintenance.</p><p> </p><p>The thesis work has been to make new maintenance programme for Westhelicopter INC. This maintenance programme will be used to follow-up the time of the components, service bulletins and ADs. Existing materials, as maintenance manuals and interviews with technical staff, was used to make more efficient maintenances programme. Work will be applied to all helicopters that Westhelicopter AB supplies.</p>

Westhelicopter INC. has an aviation workshop providing qualified helicopter maintenance in accordance with PART-145. Maintenance and administrative base is situated in Luleå at Kallax airport. The types that Westhelicopter INC are currently authorised to service are: Eurocopter AS 350 Base/Line Maintenance, Eurocopter EC 120 Base/Line Maintenance and Robinsson R44 Base/Line Maintenance.   The thesis work has been to make new maintenance programme for Westhelicopter INC. This maintenance programme will be used to follow-up the time of the components, service bulletins and ADs. Existing materials, as maintenance manuals and interviews with technical staff, was used to make more efficient maintenances programme. Work will be applied to all helicopters that Westhelicopter AB supplies.

This diploma thesis deals with the issue of maintaining airworthiness of aircraft, which is mostly limited by time, number of flew hours or number of landings. Based on the airplane data are scheduled regular services or replacement of individual parts are performed. All organizations authorized to perform these service activities must hold a certificate issued in accordance with Part M, Subpart G. Organizations authorized to provide airworthiness monitoring are referred as CAMO. The aim of my work is to create CAMO for a small organization using one to three aircraft category CS-23 and to create a description of the regulations and requirements that this organization must follow for successful continuing airworthiness management.

This project is part of a collaborative MSc training programme between the Aviation Industries of China (AVIC) and Cranfield University, aiming at enhancing the competitiveness of AVIC in both international and domestic aviation market through applying continuing airworthiness policies in the whole aircraft development process. The arrangement of the research project is that all students start with a Group Design Project which is based on the Flying Crane Project provided by AVIC. Individual research projects will address some aspects of the Flying Crane Project during the Group Design Project, and then further developed during the period for individual projects. The aim of this research is to apply the airworthiness requirements and the methodology of the Maintenance Steering Group logic (MSG-3) in the Flying Crane Project. This is because that maintenance is one of the key factors of Continuing Airworthiness, and MSG-3 logic is the most accepted and approved method to develop scheduled maintenance for civil aircrafts. The main objectives of this project include: (1) To investigate current Continuing Airworthiness regulations, including European airworthiness requirements (as the main regulation to comply with) and Chinese airworthiness regulations (as an important reference and supplement to the research); (2) To investigate the main analysis methodology of reliability and maintainability, including Damage Tolerance and Failure Mode and Effect Analysis (FMEA); (3) To analyse the data resulted from the Group Design Project using MSG-3 logic to produce a set of Continuing Airworthiness instructions, for the operator and maintenance organisation of the aircraft, from the design organization’s perspective; (4) To develop Continuing Airworthiness instructions for airline operators to compose maintenance programmes for Flying Crane aircrafts, including maintenance tasks and intervals for the selected airframe systems and structural components; and (5) To identify applicable maintenance organisations in China for Flying Crane aircrafts in accordance with both European and Chinese airworthiness requirements. On completion of this research, two aspects of Continuing Airworthiness have been investigated, including maintenance programme and maintenance organization. With MSG-3 logic, the author developed the maintenance plan for three structural components (fuselage skin panel, wing root joint, and fin-fuselage attachment) and one airframe system (fuel system) based on results from the Group Design Project. The author also investigated the Chinese domestic aircraft maintenance companies, and selected suitable maintenance organizations based on technical and economical criteria.

With the popularity of unmanned aircraft systems (UAS), there is a growing need to assess airworthiness for safe operations in shared airspace. In the context of this thesis, shared airspace implies the introduction of UAS into airspace designated for manned aircraft. Airworthiness guidelines are generally statements that state safety requirements to prevent unwanted consequences, such as aircraft accidents. Many governmental agencies such as the U.S. Federal Aviation Administration (FAA) analyzed the risks of UAS to third-parties, all personnel and properties exterior to the aircraft. This thesis concerns the adaptation of existing airworthiness documents written for manned aircraft to UAS. The proposed method has three stages that are applied in sequence to identify relevant and irrelevant airworthiness statements, the building blocks of an airworthiness document, with regard to UAS. This method is applied to MIL-HDBK-516C, used as a case study; however, the proposed methodology can be applied to any airworthiness document developed for manned aircraft. This thesis presents a list of all MIL-HDBK-516C airworthiness statements that are directly relevant, indirectly relevant, and irrelevant to UAS; additionally, the indirectly relevant airworthiness statements to UAS are provided along with suggested modification. / M.S. / With the popularity of unmanned aircraft systems (UAS), there is a growing need to assess airworthiness for safe operations in shared airspace. Airspace is the available air for aircraft to fly in; most airspaces are regulated and are subject to the jurisdiction of a particular country. In the context of this thesis, shared airspace implies the introduction of UAS into airspace designated for manned aircraft. Airworthiness guidelines are generally statements that state safety requirements to prevent unwanted consequences, such as aircraft accidents. Many governmental agencies such as the U.S. Federal Aviation Administration (FAA) analyzed the risks of UAS to third-parties, all personnel and properties exterior to the aircraft. This thesis concerns the adaptation of existing airworthiness documents written for manned aircraft to UAS. The proposed method has three stages that are applied in sequence to identify relevant and irrelevant airworthiness statements, the building blocks of an airworthiness document, with regard to UAS. This method is applied to MIL-HDBK-516C, Department of Defense Handbook: Airworthiness Certification Criteria, used as a case study. MIL-HDBK-516C is a military handbook used for airworthiness guidance. However, the proposed methodology can be applied to any airworthiness document developed for manned aircraft. This thesis presents a list of all MIL-HDBK-516C airworthiness statements that are directly relevant, indirectly relevant, and irrelevant to UAS; additionally, the indirectly relevant airworthiness statements to UAS are provided along with suggested modification.