Bewertung der Effizienz von Flugzeugen mit Hybridlaminarhaltung unter Berücksichtigung von Wolkeneinflüssen

Das Ziel dieser Arbeit ist es, die operationelle und ökonomische Effizienz von Flugzeugen mit Hybridlaminarhaltung zu bewerten. Im Vordergrund steht dabei die Frage, wie kritisch die Degradation der Laminarität durch Wolkeneinflüge ist und welche Gegenmaßnahmen zur Minderung des Einsparpotenzialverlustes geeignet sind. Dazu wurden zwei Mittel-Langstreckenflugzeuge mit Hilfe von meteorologischen Atmosphärendaten des European Centre for Medium-Range Weather Forecast hinsichtlich ihrer Effizienz untersucht. Neben der Erstellung einer globalen und auf die Luftfahrt bezogenen Wolkenklimatologie wurden vom DLR entwickelte Tools zur Trajektoriensimulation genutzt, um das reale Einsparpotenzial von Flugzeugen mit Hybridlaminarhaltung unter Berücksichtigung unterschiedlicher Kraftstoffplanungsstrategien zu ermitteln. Zudem wurde eine Umgebung zur Trajektorienoptimierung verwendet, um die Frage zu beantworten, inwieweit und unter welchen Bedingungen alternative laterale Streckenführungskonzepte geeignet sind, um durch die Vermeidung von Wolkendurchflügen die Laminaritätsdegradation zu vermindern und den ökonomischen Vorteil der Technologie zu maximieren

Improving Aircraft Maintenance Performance through Prescriptive Maintenance Strategies

In the past couple of years, predictive maintenance has arguably been the most discussed maintenance strategy in academia and industry. While it promises a significant operational easing and cost saving potential through the projection of system failures, it is characterized by a strong asset centricity; thus, it often only focuses on a system’s (projected) condition for issuing a maintenance task. Furthermore, the realized savings potential depends heavily on the performance of the underlying condition monitoring technologies. A recent study by (Haarman et al. 2018) among manufacturing companies from the Netherlands, Belgium, and Germany showed that many of these companies struggle in the identification of viable business case scenarios with predictive maintenance; mostly due to the limited maturity of the underlying condition monitoring technologies. Subsequently, this lack of business cases increases their hesitance to (further) invest in the development of the associated technologies, slowing the technological advancement unnecessarily. An integral part in the development of post-prognostics maintenance strategies is the identification of suitable systems to apply a prognostics-based maintenance strategy to and the determination of necessary minimum performance criteria of the underlying monitoring technology. However, the majority of research publications and industry efforts focusses on the development of condition-monitoring techniques itself and often oversimplifies this identification of business case scenarios and the subsequent integration of derived maintenance actions within the existing maintenance process environment. With these challenges in mind, we propose the next step in the evolution of post-prognostics maintenance strategies – the prescriptive maintenance approach. With this step, the scope of maintenance scheduling will be extended beyond the asset itself and incorporate the associated stakeholder’s objectives in the planning process, e.g. for the operator, a reduction in flight irregularities or, for the maintenance provider, a reduction in unjustified component removals (Wheeler et al. 2010). Thus, individual improvements (or possible drawbacks) – due to different maintenance strategies – can be attributed to the respective stakeholder. With this presentation, we will demonstrate the expected benefits for an automated tire condition monitoring system using our discrete-event simulation framework PreMaDe (Prescriptive Maintenance Developer). In particular, we are going to focus on the effects that different Prognostics and Health Management (PHM) technologies have on the operations of a short-/medium-haul aircraft fleet, the associated on-wing maintenance, and the spare parts inventory management. The presented results will provide a holistic view on the expected maintenance performance and not solely focus on monetary aspects – since real-life decision always require a trade-off between competing objectives or among multiple stakeholders. This will, subsequently, help maintenance practitioners to define suitable business case scenarios and determine necessary payments for stakeholders to be financially compensated for adversarial effects of such a prognostics-based maintenance strategy. Ultimately, this approach will enable the swift identification of systems that promise a significant optimization potential through the introduction of an adjusted maintenance strateg

NGT Taxi, A diagnostic Approach to Vehicle Maintenance in Remote Areas

There are certain challenges for railway vehicle maintenance in case of operating autonomous and/or in remote areas. The NGT Taxi will be constructed in a way that fullfill these requirements. The presentation gives an overview of the research status

A Comparison of Temporally Dynamic Life Cycle Assessment Methods for Ecological Evaluation in Aviation

Most Life Cycle Assessments (LCAs) in aviation are static and do not adequately reflect the long life cycles of aircraft and associated temporal impacts of emissions. However, these temporal aspects will become more important in the future, as the concept of freedom in the climate crisis is now joined by a revolutionary factor, which states that the timing of certain emissions and their consequences will play an increasingly important role in the assessment of aircraft. There are various dynamisation methods that can extend classical LCAs. A literature review including a list of benefits and limitations should provide information on which dynamic methods are particularly suitable for aviation. Especially in the aviation sector, the dynamic life cycle inventory offers great potential for mapping and evaluating the operational life of an aircraft in more detail. A thorough examination, for example with the help of a discrete-event simulation, can therefore offer the possibility of significantly improving the accuracy and quality of the LCA results and thus generate more extensive insights into the ecological impact of aircraft

Using Discrete-Event Simulation for a Holistic Aircraft Life Cycle Assessment

With growing environmental awareness and the resulting pressure on aviation, ecological impact assessments are becoming increasingly important. Life cycle assessment has been widely used in the literature as a tool to assess the environmental impact of aircraft. However, due to the complexity of the method itself and the long lifespans of aircraft, most studies so far have made strong simplifications, especially concerning the operational phase. Using a combined discrete-event simulation framework, this paper aims to ecologically assess the individual life cycle phases of an aircraft. The method will be demonstrated in a case study of an A320 and subsequently compared with findings from the literature. Despite the significant environmental impact of flight operations, which covers almost 99.8% of the entire life cycle of the aircraft, a detailed consideration of all life cycle phases is essential to serve as a reference for the ecological assessment of novel aircraft concepts. The presented assessment method thus enables a holistic analysis at an early stage of the design process and supports the decision-making for new technologies and operational changes

Nutzung präskriptiver Instandhaltungsansätze in der Luftfahrt zur vorausschauenden Materialbedarfsplanung

Durch kontinuierliche Bemühungen der Digitalisierung und Ansätze der dauerhaften Systemüberwachung ist es in der Luftfahrt zunehmend möglich, aufkommende Schadensfälle vor ihrem Eintreten zu erkennen und Instandhaltungsereignisse entsprechend bedarfsgerecht zu planen, so dass notwendige Material- und Ressourceneinsätze möglichst minimal gehalten werden können. Da die dazugehörigen Zustandsüberwachungssysteme jedoch häufig noch in frühen Phasen ihrer technologischen Reife stehen, sind diese Prognosen mit gewissen Unsicherheiten behaftet. Es ist daher erforderlich, die Performance solcher Ausfallprognosen in Relation mit dem zu erwartenden Nutzen in der Instandhaltung und Ersatzteilversorgung zu betrachten (bspw. Wie ändert sich der Ersatzteilbedarf reparaturfähiger Komponenten bei Nutzung einer prognose-basierten Instandhaltung im Vergleich zu einer rein korrektiven Instandhaltung, falls das Überwachungssystem eine durchschnittliche Fehlalarmrate von 10% besitzt?). Im Rahmen dieses Vortrag wird das generelle Konzept der präskriptiven Instandhaltung kurz angerissen, um anschließend die modellierungstheoretischen Ansätze der diskreten Ereignissimulation zur verbesserten Ersatzteilversorgung vorzustellen. Das Ziel ist schlussendlich, Anwendern und Systemingenieuren eine Hilfestellung an die Hand zu geben, anhand dessen zum einen die Auswirkungen einer geänderten Instandhaltungsstrategie auf die beteiligten Stakeholder abgeschätzt und zudem auch Mindest-Performance-Kriterien an eine entsprechende Zustandsüberwachungstechnologie definiert werden können

Developing prescriptive maintenance strategies in the aviation industry based on a discrete-event simulation framework for post-prognostics decision making

The aviation industry is facing an ever-increasing competition to lower its operating cost. Simultaneously, new factors, such as sustainability and customer experience, become more important to differentiate from competitors. As aircraft maintenance contributes about 20% to the overall cost of airline operations and can significantly influence other objectives of an airline as well, maintenance providers are required to constantly lower their cost share and contribute to a more reliable and sustainable aircraft operation. Subsequently, new condition-monitoring technologies have emerged that are expected to improve maintenance operations by reducing cost and increasing the aircraft’s availability. As many of these technologies are still in their technological infancy, it is necessary to determine the expected benefit for the airline operations with the given technological maturity and to develop suitable maintenance strategies that incorporate the newly gained insights. With this paper, a discrete-event simulation framework is developed that uses established parameters to describe a condition-monitoring technology’s performance and subsequently develops a suitable prescriptive maintenance strategy. Therefore, it enables the adjustment of the optimization goal for the developed strategy to incorporate performance features beyond the frequently used financial indicators. The developed capabilities will be demonstrated for the tire pressure measurement task of an Airbus A320

Concept and Economic Evaluation of Prescriptive Maintenance Strategies for an Automated Condition Monitoring System

In order to reduce operating costs and increase the operational stability, the aviation industry is continuously introducing digital technologies to automate the state detection of their assets and derive maintenance decisions. Thus, many industry efforts and research activities have focused on an early state fault detection and the prediction of system failures. Since research has mainly been limited to the calculation of remaining useful lifetimes (RUL) and has neglected the impact on surrounding processes, changes on the objectives of the involved stakeholders, resulting from these technologies, have hardly been addressed in existing work. However, to comprehensibly evaluate the potential of a fault diagnosis and failure prognosis system, including its effects on adjacent maintenance processes, the condition monitoring system’s maturity level needs to be taken into account, expressed for example through the technology’s automation degree or the prognostic horizon (PH) for reliable failure projections. In this paper, we present key features of an automatic condition monitoring architecture for the example of a Tire Pressure Indication System (TPIS). Furthermore, we develop a prescriptive maintenance strategy by modeling the involved stakeholders of aircraft and line maintenance operations with their functional dependencies. Subsequently, we estimate the expected implications for a small aircraft fleet with the introduction of such a monitoring system with various levels of technological maturity. Additionally, we calculate the maintenance cost savings potential for different measurement strategies and compare these results to the current state-of-the-art maintenance approach. To estimate the effects of implementing an automated condition monitoring system, we use a discrete-event, agentbased simulation setup with an exemplary flight schedule and a simulated time span of 30 calendar days. The obtained results allow a comprehensive estimation of the maintenance related implications on airline operation and provide key aspects in the development of an airline’s prescriptive maintenance strategy

An Assessment of the Economic Viability of Engine Wash Procedures on the Lifecycle Cost of an Aircraft Fleet

Aircraft operators find themselves in an environment in which the economic and ecological pressure on companies is constantly increasing. To address this, significant improvements of aircraft efficiency are necessary. One way to reduce both operating cost and the environmental impact is to regularly perform on-wing engine washes which reduce the exhaust gas temperature as well as improve aircraft fuel consumption. To estimate the lifecycle impact of engine cleaning procedures, a variety of factors must be taken into account, ranging from environmental to operational. The lifecycle costing method developed by DLR, known as LYFE (Lifecycle Cash Flow Environment), enables the consideration of various factors to investigate the impact of engine washes over the lifetime of an aircraft or fleet. LYFE uses discrete event simulation to model the product lifecycle from order to operation until disposal of an aircraft fleet. For this analysis the tool is extended to separate the lifecycles of the engines and those of the aircraft, which enables the modeling of switching engines among aircraft. To more realistically represent engine fouling and engine performance degradation, representative weather data at airports is also included in the simulation. Using this information, we have developed a prognostics model to monitor the health of the engine, predict the timing of engine shop visits and automatically and dynamically schedule engine wash events. For the latter, three different algorithms varying in the prognostic horizon were developed and compared to one another. The results show that engine washing can improve the time on wing of the engine by up to 2240 flight cycles. Due to lifetime limitations by life limited parts and assumptions within this study, no extension of the service life of the engine can be achieved within the scope of this investigation. On the other hand, the fuel cost could be reduced at an average of 1.2% while the total cost remained the same. With this holistic view of how engine washes within a fleet influence the time on wing of the engine and affect its lifecycle cost a much more realistic statement about this on-wing maintenance action is possible