Maintenance, Repair, Overhaul Research Articles

Engine option in aircraft purchase: Company strategies and policy implications

Airlines select an aircraft’s engine simultaneously while purchasing the aircraft. Usually, an aircraft model has multiple engine options, but recently the number of engine options has been decreasing. We develop a three-echelon supply chain model including engine manufacturers, aircraft manufacturers, and airlines to analyze the engine options in airlines’ new aircraft purchases. We show that given an airline’s existing fleet composition, larger fleet size and higher aircraft production efficiency would make it more likely to choose multiple engine options. In contrast, higher production costs and engine substitutability would lead to a shift to a single engine or hinder the airline’s fleet expansion. In the model, we highlight the impact of MRO (Maintenance, Repair, Overhaul) costs with economies of scale on airline engine option decisions as well. In particular, our theoretical findings suggest that the airline would buy more aircraft that are the majority types in their existing fleets, thus crowding out the minority ones. Our findings provide a reasonable explanation for the homogeneity of engine options and provide policy implications regarding airline expansion and aviation supply chain development.

Dynamic production capacity assessment of aircraft overhaul shop based on digital twin

Aircraft overhaul is of the highest level in aircraft MRO (Maintenance, Repair, Overhaul), which is an important and necessary activity for ensuring safety and reliability of aircraft throughout its whole lifecycle. Production capacity of aircraft overhaul shop has huge strategic value and determines the cycle time and throughput of the overhauled aircraft. However, due to the inherent complexity and stochasticity, aircraft overhaul tasks are generally executed manually by skilled workers, whose stochastic task execution time (TET) makes it challenging to assess the production capacity of aircraft overhaul shop. Digital twin provides an up-to-date technical measure to simulate, evaluate, and predict the whole lifecycle process of its physical entity, which makes it possible to tackle the complexity and stochasticity of aircraft overhaul process. This paper proposes to apply digital twin to assess the production capacity of aircraft overhaul shop dynamically. Firstly, the aircraft overhaul process and its dynamic production capacity assessment are analyzed. A modeling framework of aircraft overhaul shop digital twin is proposed with a novel twin fusion mechanism. Then, an improved kernel density estimation (KDE) method and a quota hour density proportion (QHDP) method are proposed and verified to process stochastic TET for production capacity assessment. Finally, the digital twin of a typical aircraft avionics repair shop is constructed to assess its production capacity. Four assessment results are compared with real observations from the aircraft avionics repair shop, which verifies the feasibility and advantage of the proposed methodology. A bottleneck analysis is also conducted to optimize the production capacity, which provides managerial insights.

A techno-economic perspective on 3D printing for aerospace propulsion

This work aims to provide a fresh techno-economic perspective on the use of 3D printing (3Dp) for aerospace propulsion. 3Dp has brought to the aerospace industry several improvements in various areas. Historically, it has been used to produce jigs and fixtures, surrogates, mounting brackets, and prototypes. More recently, component production by 3Dp has further evolved, permitting more design freedom, lighter structures, quicker prototyping and iteration, supply chain optimization, increased customization and personalization, improved maintenance, repair, overhaul (MRO), and innovation for better materials. 3Dp is particularly relevant to designing better, quicker, and cheaper new components that integrate into more performing systems. Looking ahead, expected developments include the increased scale of 3Dp production, further enhanced performance of components and systems, in-situ manufacturing, and integration with other technologies such as Artificial Intelligence (AI) or the Internet of Things (IoT). From a market perspective, global 3Dp in the aerospace market was valued at USD 1.76–2.66 billion in 2021, with a predicted compound annual growth rate (CAGR) of 19.4–20.23 % over the next few years. Drivers for an even larger CAGR are the expected new developments, such as hydrogen general aviation, urban air mobility (UAM), electrification of aircraft, and hypersonic commercial and military applications.

MIXED-INTEGER MODEL OF OPTIMIZATION OF PRODUCTION AND TECHNOLOGICAL CAPACITIES OF REGIONAL SERVICE CENTRES FOR THE REPAIR OF COMPONENTS AND ASSEMBLIES OF AVIATION EQUIPMENT

The problem of developing an algorithm for structural-parametric optimization of production and technological capacities of regional service centers for the repair of components and assemblies of aviation equipment is considered. A mixed-integer model has been formed, where integer variables determine the composition of maintainable components (MF) of aviation equipment and repair levels, and continuous variables are indicators of the cost and labor intensity of work with them. It is shown that the problem under consideration relates to difficult combinatorial optimization problems, that is, there is no polynomial algorithm for solving it in a reasonable time. However, taking into account the specifics of the task, in some cases, allows you to build calculation schemes that provide sufficient accuracy of the solution and an acceptable time. The criterion for choosing the optimal solution is proposed - costs for ensuring technical operation, which are necessary to achieve a given operational readiness coefficient. An algorithm for calculating the best variant of the service center structure, which is based on the dependence of the specific weight of the decision to repair each product in the service center, has been developed. The specific weight reflects the difference between the costs of using the service center exclusively as an intermediate warehouse for storing each type of component parts with their repair at the manufacturer, and the costs of creating a repair infrastructure in the service center of the components warehouse for the repair of component parts and performing repairs before the development of the assigned product resource. Options for organizing the maintenance, repair, overhaul (MRO) system of a typical product in the traditional way are consistently considered, where it is assumed to organize a two-level warehouse system and with the deployment of regional service centers by industry for the repair of components and aggregates. The possibility of reducing the costs of MRO for the product life cycle by up to 15 % due to a reduction in the level of stocks of expensive MF, as well as the costs of their repair and transportation is show, the results of calculations are presented.

Capability development in hybrid organizations: enhancing military logistics with additive manufacturing

Additive Manufacturing (AM) has the potential to revolutionize key aspects of Military Logistics and partnerships between governmental and industrial organizations. Extreme outsourcing of key capabilities has created complex and deep hybrid organizations between armed forces and the private sector. In this study, the internal and external effects and requirements of Additive Manufacturing in the context of the hybrid organization of The Finnish Defence Forces (FDF) and its strategic partner in Maintenance, Repair, Overhaul (MRO), and Millog Oy were studied. First, with a literature review, we sought to link the capability development processes and the change drivers within them in both military and commercial contexts. Then, we utilized an existing, structured capability model used by the FDF (DOTMLPFI) and its individual change drivers to form an initial concept of AM as a part of the hybrid organization in question. The initial concept shows that AM can increase the performance of the commercially backed Military Logistic System by mitigating the risks of spare parts shortage in case of supply line disturbances and by facilitating localized spare parts production. However, the different primary goals of the military and commercial organizations and the contractual base of the hybrid organization impose constraints on the capability development process. Administrative decision-making across the organizations and the conflict between maximizing military and commercial potential are the key challenges in maintaining joint-capability systems of hybrid organizations.

ANALISIS PERENCANAAN PENGADAAN KOMPONEN REM PESAWAT B737-800 NG BERDASARKAN SATUAN CYCLE DAN FLIGHT HOURS DI PT ABC

As one of the MRO (Maintenance, Repair, Overhaul) company PT ABC had the significant problems in the last 3 years, including concerns regarding the difficulty of determining the amount of material availability and timing of procurement the material appropriate to support maintenance activities. In this case the components studied are two type brake of aircraft the first one is brake assembly and the second one is brake Goodrich which installed on B737-800 aircraft NG. Based on historical data, in last 3 years PT ABC have a number of component shortage that continues to grow, in last year PT ABC had 12 unit shortage component for brake assembly and 13 unit shortage component for brake goodrich. It is gave the negative impact for company and also customer PT ABC. To overcome these problems need to be analyzed how to determine the accuracy the number of brake requests that will removal in future periods which resulting the accuracy of the flight time (dispatch reliability/delay time). The proccess in this reserach first determine the life time of brake, determine the quantity of removal brake, schedule of removal brake, account the forecast of requirement brake in next years and determine the planning of material requirement for maintenance proccess. The forecasting using single exponential smoothing methode to determine forecasting result of brake requirement in 2017. This methode consider the smallest standar error estimate of forecasting demand to get the exact result. Morever MRP (material requirement planning) methode used to determine the procurement components planning (Petition Requirement Planning) with forecasting data from previous year's demand. Based on studies result showed that the quantity of brake assembly and brake Goodrich types that should be available for the removal of as many as 13 units per each type of brake for a period in 2017, while the limit (age component) of brake assembly 38 days and 41 days for brake Goodrich and the estimation schedule of brake removal is the last date installation brake plus the actual age of brake that has determined the schedule of brake assembly in 21st of the months 12 and the 2nd of the month 11 for brake Goodrich and result are showed that MRP decrease the shortage of brake assembly 1 unit and decrease the shortage of brake goodrich 2 unit.

Safety Leadership and Safety Behavior in MRO Business: Moderating Role of Safety Climate in Garuda Maintenance Facility Indonesia

The purpose of this study is to understand the influence of Safety Leadership and Safety Communication on Safety Climate and Safety Behavior at work from employees’ point of view. This research was conducted at Soekarno-Hatta International Airport, Indonesia and businesses associated with Maintenance, Repair & Overhaul (MRO) owned by PT. Garuda Maintenance Facility Aero Asia Tbk. (GMF), which operates locally and internationally. It was conducted through questionnaires and aimed to reflect the organization's safety. The survey was conducted among 342 staffs of several departments in GMF. The result of this study is a positive correlation between the research questions and hypotheses in which safety leadership has a positive effect on safety climate standard with a coefficient of 0.204. That is to say, the higher the level of safety leadership, the higher the level of safety climate. Safety climate has significant effect on safety behavior, and safety communication has positive effect on safety climate. Furthermore, safety leadership has no significant effect on safety behavior. Safety leadership has significant effect on safety behavior through safety climate or partially mediates. This research is expected to contribute on safety behavior in an organization, which means reducing chance of work accidents and promoting the wellness of both employees and employers.

Hybrid-additive manufacturing cost model: A sustainable Through-Life Engineering support for Maintenance Repair Overhaul in the Aerospace

The drive for a more flexible Through-life Engineering servicing technology that can enhance both productivity and profitability for the operation of maintenance, repair, overhaul (MRO) in the aerospace implores harnessing the innovation of hybrid-additive manufacturing (HAM). Hybrid manufacturing system seeks to reduce cost by utilizing the tool-less production principle of additive manufacturing combine with the conventional subtractive manufacturing for product finishing or post-processing. HAM has many merits that make it an attractive option in manufacturing of high performance products as peculiar to MRO businesses. Therefore, this paper aims to establish a cost model derived from a “Time Driven Activity Based Costing” approach for the technological integration of Hybrid system to increase economic competitiveness of highly MRO services in the aerospace industry. Hence, a unique cost formulation method was investigated through analytical technique in cost engineering models for the purpose of manufacturing processes.

A function availability-based integrated product-service network model for high-end manufacturing equipment

Abstract Nowadays, product-service system (PSS) has become a popular topic that devotes to implement the integration of products and services to meet function demands. However, in the usage phase, the integration of high-end manufacturing equipment (HEME) and maintenance-repair-overhaul (MRO) services is still insufficient to ensure the long-term continuous availability for function implementation (named as function availability). Thus, in view of function information in function availability, this paper develops a function availability-based integrated product-service network model (IPSN) from the perspective of complex network. This model merges the obtained function action units, structure module units as well as service execution activities and reveals their implement-maintain-ensure mapping mechanism based on the modeling processes of function network, structure network, service network and interdependent network of networks. In this model, functions are regarded as the goals serviced, structures are deemed as the objects serviced and services are the corresponding execution processes. With this model, the function availability could be better ensured with the delivery of the linked more critical integrated services. In order to illustrate the detailed modeling process, a case for feeding function of numerical control honing machine 2MK2263 × 200 is studied. From the evaluation and comparison results, it could be seen that this model not only realizes the integration of products and services to ensure the concerned functions, but also provides a vital foundation for the identification of critical nodes and the effective service configuration for availability.

Analysis of employability for the civil aviation maintenance graduates of Turkey

PurposeWith every passing day, the center of gravity for air traffic for the Middle East and Turkey is shifting toward becoming a center for airway transport, maintenance, repair, overhaul (MRO) and transfer. The MRO sector is gaining importance because of this increase in Turkey. The purpose of this study is to examine the future employability of the graduates receiving civil aviation maintenance training in Turkey.Design/methodology/approachThe paper uses past seven years’ data about maintenance personnel of Turkey. It includes all-level students, recently working personnel and retired personnel of each year. Regression analysis and Markov analysis were used to show the prediction of aviation maintenance personnel.FindingsThe paper provides quantitative results about employability of maintenance personnel under the real numbers of alumni and working and retired personnel in Turkey. The results show that the number of graduates will be greater than the number of staff members in certifying categories in 2018. Presently, Turkey meets the employment expected, but in the future, aviation maintenance personnel number is rising, and there will be an excess number of graduates left over in Turkey.Research limitations/implicationsBecause of the chosen region, Turkey, the research results may lack generalizability. Therefore, researchers are encouraged to conduct analysis for other countries which have an important role in aviation.Practical implicationsThe paper includes implications for the government maintenance personnel policy and educational policy for managing all types of maintenance personnel in Turkey.Originality/valueThis kind of personnel needs analysis has not been done before, and this is the originality of this paper. It will in turn lead to an analysis of planning for allocation of maintenance staff and alumni. The authors collected all official numbers about maintenance personnel from Turkish Student Selection and Placement Center of Turkey, Turkish Technic and Turkish Civil Aviation Reports.

Designing Contracts for Aero-engine MRO Service Providers: Models and Simulation

The aero-engine Maintenance-Repair-Overhaul (MRO) service provider has begun to adopt the product-service system (PSS) offering in order to maintain their competitiveness. Such total solution approach combines an availability-based service contract with product offerings (e.g., leasing). The current MRO service provider's contract design method is inadequate to support this offering. Miscalculation often occurs, because many of the decisions are often based on intuitions and experiences, resulting in lower quality, higher cost and longer turnaround time for the maintenance. This paper proposes an enhanced contract design method that is more scientific through the simulation modelling. The models incorporate both customers’ requirements and the shop floor's operational availability. The paper provides discussion on how the results of the simulation of the models can be used to support decision making and the design of availability based contracts.

MTU Aero Engines: Thriving on Alliances?

This teaching case covers MTU Aero Engines, a German aerospace company. The focus is on alliances both vertical and horizontal to highlight a unique strategic position of the firm as a first tier systems supplier to the aircraft engine OEMs. The company enjoys a strong position in a web of relations involving most OEMs. However, more and more risk-sharing contracts involving highly innovative and complex parts means that MTU must manage its risk portfolio. The company has entered other engine related services such as the maintenance-repair-overhaul (MRO) market characterized by far more players than the engine parts business. At one stage the company was sold to the leverage-buyout company KKR in the US, raising many political issues regarding the military part of the company. Although many see MTU as a company that could become the fourth independent OEM in aero engines (GE, Rolls Royce and Pratt & Whitney) others argue against such a move. The case has been used in MBA strategy classes to highlight the costs and benefits of a complex web of strategic alliances.

An Ontological Knowledge-Based System for Maintenance, Repair and Overhaul Services

Manufacturing enterprises are making more efforts in providing high value added services in addition to their traditional product business. An ontological knowledge-based product service system (PSS) is present in this paper which is used as a decision support tool and offers a means of supporting decision-making for maintenance, repair, overhaul (MRO) solution finding. An ontology-based knowledge representation is developed to represent, accumulate and collect knowledge and experience emerged during the MRO services, which realizes the knowledge originated from the service process and served service process. An ontology-based knowledge reasoning method is used to find the semantically similar generalized product service cases. The PSS configuration scheme set is obtained by optimizing and assessing the selected cases. The reference service solutions for the specific customer requirements will be created using the proposed PSS. An initial attemp has been made to demonstrate the role of PSS as a decision support tool for MRO services.