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1 – 10 of 54Yichen Qin, Hoi-Lam Ma, Felix T.S. Chan and Waqar Ahmed Khan
This paper aims to build a novel model and approach that assist an aircraft MRO procurement and overhaul management problems from the perspective of aircraft maintenance service…
Abstract
Purpose
This paper aims to build a novel model and approach that assist an aircraft MRO procurement and overhaul management problems from the perspective of aircraft maintenance service provider, in order to ensure its smoothness maintenance activities implementation. The mathematical model utilizes the data related to warehouse inventory management, incoming customer service planning as well as risk forecast and control management at the decision-making stage, which facilitates to alleviate the negative impact of the uncertain maintenance demands on the MRO spare parts inventory management operations.
Design/methodology/approach
A stochastic model is proposed to formulate the problem to minimize the impact of uncertain maintenance demands, which provides flexible procurement and overhaul strategies. A Benders decomposition algorithm is proposed to solve large-scale problem instances given the structure of the mathematical model.
Findings
Compared with the default branch-and-bound algorithm, the computational results suggest that the proposed Benders decomposition algorithm increases convergence speed.
Research limitations/implications
The results among the same group of problem instances suggest the robustness of Benders decomposition in tackling instances with different number of stochastic scenarios involved.
Practical implications
Extending the proposed model and algorithm to a decision support system is possible, which utilizes the databases from enterprise's service planning and management information systems.
Originality/value
A novel decision-making model for the integrated rotable and expendable MRO spare parts planning problem under uncertain environment is developed, which is formulated as a two-stage stochastic programming model.
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M. El Hayek, E. van Voorthuysen and D.W. Kelly
Maintenance is constantly challenged to increase productivity by maximizing up‐time and reliability while at the same time reducing maintenance expenditure and investment…
Abstract
Purpose
Maintenance is constantly challenged to increase productivity by maximizing up‐time and reliability while at the same time reducing maintenance expenditure and investment. Traditional reliability models are based on detailed statistical analysis of individual component failures. For complex machinery, especially involving many rotable parts, such analyses are difficult and time‐consuming. This paper aims to propose an alternative method for estimating and improving reliability.
Design/methodology/approach
The methodology is based on simulating the up‐time of the machine or process as a series of critical modules. Each module is characterized by an empirically derived failure distribution. The simulation model consists of a number of stages including operational up‐time, maintenance down‐time and a user‐interface allowing maintenance and replacement decisions.
Findings
Initial analysis performed on aircraft gas‐turbine data yielded an optimal combination of modules out of a pool of multiple spares, resulting in an increased machine up‐time of 16 percent.
Practical implications
The benefits of this methodology are that it is capable of providing reliability trends and forecasts in a short time frame and is based on available data. In addition, it takes into account the rotable nature of many components by tracking the life and service history of individual parts and allowing the user to simulate different combinations of rotables and operating scenarios. Importantly, as more data become available or as greater accuracy is demanded, the model or database can be updated or expanded, thereby approaching the results obtainable by pure statistical reliability analysis.
Originality/value
The model presented provides senior maintenance managers with a decision tool that optimizes the life cycle maintenance cost of complex machinery in a short time frame by taking into account the rotable nature of modules.
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Jan Block, Alireza Ahmadi, Tommy Tyrberg and Peter Söderholm
The purpose of this paper is to present the prerequisites for a part-out-based spares provisioning (PBSP) programme during the phase-out of an aircraft fleet. Furthermore…
Abstract
Purpose
The purpose of this paper is to present the prerequisites for a part-out-based spares provisioning (PBSP) programme during the phase-out of an aircraft fleet. Furthermore, associated key decision criteria are identified and a framework for the phase-out management process is presented.
Design/methodology/approach
Once a decision has been taken to phase-out an aircraft fleet, a number of routines for operations, maintenance and storage are affected and new tasks and functions must be introduced before initiating the actual parting-out process. A decision-making system and a management framework is needed to manage spares planning during the end-of-life phase to ensure availability at minimum cost and to ensure a manageable risk of backorders.
Findings
For PBSP programme during the phase-out of an aircraft fleet to succeed and be cost-effective, a number of linked processes, tasks and decisions are required, e.g., those included in the framework proposed in this paper (see Figure 3). A successful implementation of PBSP also requires that these processes and tasks are carried out in a timely manner and that the communications between the concerned parties are prompt, clear and direct. One experience from the studied case is that close and trustful contacts and cooperation between the operator and maintenance provider(s) will greatly facilitate the process.
Originality/value
Although the PBSP method is fairly commonly applied within both the military and the civilian sector, somewhat surprisingly very literature has been published on the subject. Indeed, remarkably little has been published on any aspects of maintenance during the end-of-life period.
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Abstract
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The management of materials to support aircraftmaintenance is studied. In a situation where thesafety stock is determined using a rule of thumbthat does not differentiate the…
Abstract
The management of materials to support aircraft maintenance is studied. In a situation where the safety stock is determined using a rule of thumb that does not differentiate the demand variation, the problem of low service level of expendables cannot be solved unless this rule is changed. A new guide for safety stock, taking demand pattern into consideration, is introduced. In addition, more reordering of low cost items is automated to ease slightly the high manpower utilisation, and put more effort where it counts most – monitoring and expediting high cost items. Other problems are related to loss and repair cost of the repairable items.
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A device for steering an aircraft having a jet propulsion nozzle is characterized by a tubular member 4 having a longitudinal slot 2, mounted at the nozzle outlet and rotable…
Abstract
A device for steering an aircraft having a jet propulsion nozzle is characterized by a tubular member 4 having a longitudinal slot 2, mounted at the nozzle outlet and rotable relatively thereto about its axis, the latter being perpendicular to the nozzle axis, the slot opening into the jet at an angle depending on the position of member 4, the latter being connected to a source of gas under pressure. In the embodiment of FIG. 1, a rectangular section nozzle 1 is provided with a curved smooth extension 3 along one of its longer sides, and has on its opposite side a cylinder 4, provided with a slot 2, rotatable in a part cylindrical housing 5 secured to the nozzle. A servo‐operated toothed rack may rotate a pinion fast to the cylinder. The interior of the cylinder is connected through a valve to a source of pressure, e.g. the compressor or combustion chambers of a turbo‐jet unit, so that a transverse jet of variable direction issues from slot 2. Variation of the direction of the transverse jet varies the direction of the main jet to control the aircraft, In a modification, the housing 5 comprises a wide slot, and a wide slot is provided in the cylinder 2, so that rotation thereof causes the slots more or less to overlap, controlling the quantity of flow in the directing jet. In this case the valve in the pressure supply line, which may be of the simple full on or full off type, may be omitted.
Michael MacDonnell and Ben Clegg
To develop a systems strategy for supply chain management in aerospace maintenance, repair and overhaul (MRO).
Abstract
Purpose
To develop a systems strategy for supply chain management in aerospace maintenance, repair and overhaul (MRO).
Design/methodology/approach
A standard systems development methodology has been followed to produce a process model (i.e. the AMSCR model); an information model (i.e. business rules) and a computerised information management capability (i.e. automated optimisation).
Findings
The proof of concept for this web‐based MRO supply chain system has been established through collaboration with a sample of the different types of supply chain members. The proven benefits comprise new potential to minimise the stock holding costs of the whole supply chain whilst also minimising non‐flying time of the aircraft that the supply chain supports.
Research limitations/implications
The scale of change needed to successfully model and automate the supply chain is vast. This research is a limited‐scale experiment intended to show the power of process analysis and automation, coupled with strategic use of management science techniques, to derive tangible business benefit.
Practical implications
This type of system is now vital in an industry that has continuously decreasing profit margins; which in turn means pressure to reduce servicing times and increase the mean time between them.
Originality/value
Original work has been conducted at several levels: process, information and automation. The proof‐of‐concept system has been applied to an aircraft MRO supply chain. This is an area of research that has been neglected, and as a result is not well served by current systems solutions.
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Aero Systems of Miami, Florida, specialises in the sale of like‐new, FAA overhauled certified aircraft rotable equipment at a fraction of the cost and lead time required by the…
Abstract
Aero Systems of Miami, Florida, specialises in the sale of like‐new, FAA overhauled certified aircraft rotable equipment at a fraction of the cost and lead time required by the factory. Aero Systems will be exhibiting for the first time in Britain and are seeking an agent for the UK and Europe.
The airworthiness and availability of all Swissair aircraft is the responsibility of the Engineering and Maintenance Department at Zurich. The extensive facilities available are…
Abstract
The airworthiness and availability of all Swissair aircraft is the responsibility of the Engineering and Maintenance Department at Zurich. The extensive facilities available are utilised to undertake all manner of work on the airline's equipment and at the same time be prepared to carry out allotted tasks within the agreement of the KSSU group of airlines (KLM, SAS, Swissair and UTA). In addition, “third party work” can be performed for these or other operators. It is notable that some 20% of the total performed on Swissair aircraft is undertaken by the KSSU partners. The Engineering and Maintenance Department of Swissair is also actively involved in the specification and purchase of new aircraft for the airline's fleet.