JOB SHOP SCHEDULING AT IN-HOUSE REPAIR DEPARTMENT IN COLD SECTION MODULE CT7 ENGINE TO MINIMIZE MAKESPAN USING GENETIC ALGORITHM AT PT XYZ

PT XYZ is an aircraft manufacturer that was established to facilitate in terms of maintenance of aircraft engines and industrial machinery which are owned by Indonesia. Workscopes which are conducted by PT XYZ is inspection, repair, and overhaul on aircraft engines. Based on historical data, PT XYZ has FCFS scheduling type that makes the process flow of repair at in-house department becomes longer. Based on existing capacity, PT XYZ can make the repair process into a job shop scheduling which is the type of scheduling that allows the flow of the process of becoming a parallel and shorter. Based on these circumstances, this study aims to make a improvement to machine scheduling becomes job shop scheduling using genetic algorithm to minimize makespan of existing scheduling. The data which is used to create a job shop scheduling is routing job and operation, the amount of machines, type of machine, and processing time. The data will be used as input in genetic algorithms. Some of the parameters used in the genetic algorithm is the population size, the mutation opportunities, opportunities crossovers, and maximum generation. The first process in the algorithm is to make the population consisting of several chromosomes. Furthermore, each chromosome will be evaluated by the fitness value, will be done by selection operation, crossover operation, and mutation operation to gain higher fitness values until termination process is fulfilled. Based on the calculation of makespan, fitness, and utilization of each machine then obtained an improvement scheduling to minimize makespan until 54,5 hours or by 64.38% of the existing condition. Keywords: Job shop scheduling, genetic algorithm, makespan, fitness, FCF

Report on visit to four North American airlines

The object of the visits was to discuss the current state-of-the-art with the Engineering Departments of several North American airlines which were known to be leading the field in the application of certain advanced techniques. In the limited time available it was decided to confine the talks mainly to those topics on which the chosen operators were known to have had unique experience. This note is presented in chronological sequence and is only intended to be a record of the information gathered; no derivations, or comparisons with other operators, are made. United Air Lines were visited first and reliability programmes are detailed, although the application of critical path techniques to aircraft and engine overhaul is summarised. Continental Air Lines are noted for their use of the continuous maintenance philosophy, and this is reported next. The third visit was to Air Canada where talks ranged from the applications of operations research and electronic data processing (EDP) techniques to aircraft evaluation procedures. Finally the PanAm aircraft system reliability programme is reviewed, together with a note on their general LDP engineering and maintenance activities. A bibliography is given, although it should be appreciated that some of the items listed contain information which may be commercially secure

Working Notes from the 1992 AAAI Spring Symposium on Practical Approaches to Scheduling and Planning

The symposium presented issues involved in the development of scheduling systems that can deal with resource and time limitations. To qualify, a system must be implemented and tested to some degree on non-trivial problems (ideally, on real-world problems). However, a system need not be fully deployed to qualify. Systems that schedule actions in terms of metric time constraints typically represent and reason about an external numeric clock or calendar and can be contrasted with those systems that represent time purely symbolically. The following topics are discussed: integrating planning and scheduling; integrating symbolic goals and numerical utilities; managing uncertainty; incremental rescheduling; managing limited computation time; anytime scheduling and planning algorithms, systems; dependency analysis and schedule reuse; management of schedule and plan execution; and incorporation of discrete event techniques

A coloured Petri net framework for modelling aircraft fleet maintenance

The aircraft fleet maintenance organisation is responsible for keeping aircraft in a safe, efficient operating condition. Through optimising the use of maintenance resources and the implementation of maintenance activities, fleet maintenance management aims to maximise fleet performance by, for example, ensuring there is minimal deviation from the planned operational schedule,that the number of unexpected failures is minimised or that maintenance cost is kept at a minimum. To obtain overall fleet performance, the performance of individual aircraft must first be known. The calculation of aircraft performance requires an accurate model of the fleet operation and maintenance processes. This paper aims to introduce a framework that can be used to build aircraft fleet maintenance models. A variety of CPN (coloured Petri nets) models are established to represent fleet maintenance activities and maintenance management, as well as the factors that have a significant impact on fleet maintenance including fleet operation, aircraft failure logic and component failure processes. Such CPN models provide an ideal structured framework for Monte Carlo simulation analysis, within which calculations can be performed in order to determine numerous fleet reliability and maintenance performance measures

Advanced knowledge system for coatings and the gas turbine MRO industry

The growth of data generated within thermal spraying is, for many, a daunting business. Yet, this growing resource represents a largely untapped and potentially valuable asset capable of providing 'knowledge' rather than just 'information'. Many companies already use a range of Web based tools. However, the Web itself is changing and the vision for the future, the 'Semantic Web', is set to revolutionise how business will be done. One important aspect of this Web 'future' is that web pages will be greatly enriched and data will have additional information (tags) which help to describe it and more significantly, put the data into a context. This will enable machine readability and the use of query languages to ask direct questions. Following on from ideas introduced at ITSC 2007, a proof of concept demonstrator has been built for thermal spray coatings used in the Maintenance Repair and Overhaul (MRO) of gas turbines. A system has been built which stores and manipulates a range of data including; aircraft deliveries, RSS feeds of aircraft sales, engine types, MRO business details, thermal spray coasystem and discusses its future potential

Aircraft Engines Maintenance Costs and Reliability: An Appraisal of the Decision Process to Remove an Engine for a Shop Visit Aiming at Minimum Maintenance Unit Cost

Dissertação apresentada como requisito parcial para obtenção do grau de Mestre em Estatística e Gestão de Informação.The decision to remove an aircraft engine for SV is not a deterministic process. The decision is taken under conditions ok risk or uncertainty and some subjectivity. In this document it is presented a case study using a decision tree to decide the best time to remove an engine with high FH since last SV. This case study and the answers from engine experts to a questionnaire about the decision process provide information that may assist to decide how to optimize engine time on-wing

The MICRO-BOSS scheduling system: Current status and future efforts

In this paper, a micro-opportunistic approach to factory scheduling was described that closely monitors the evolution of bottlenecks during the construction of the schedule, and continuously redirects search towards the bottleneck that appears to be most critical. This approach differs from earlier opportunistic approaches, as it does not require scheduling large resource subproblems or large job subproblems before revising the current scheduling strategy. This micro-opportunistic approach was implemented in the context of the MICRO-BOSS factory scheduling system. A study comparing MICRO-BOSS against a macro-opportunistic scheduler suggests that the additional flexibility of the micro-opportunistic approach to scheduling generally yields important reductions in both tardiness and inventory

Improved aviation readiness and inventory reductions through repair cycle time reductions using modeling and simulation

This thesis research focuses on improved aviation readiness and reductions in pipeline inventory investment through repair Turn Around Time reductions related to the component repair processes internal to the Naval Aviation Depot (NADEP). Specific emphasis was given to the repair flow of a specific component from induction into the Depot for repair to the ultimate availability for sale to customers in a ready-for-issue status. The research models the current NADEP repair process flow and simulates enhancements to the process flow. These enhancements identify savings of over $52,000 in repair pipeline inventory investment for the candidate item. Our model and associated simulations provide NADEP with graphical and quantitative feedback which demonstrates the impact of process flow enhancements on repair Turn Around Time and Work in Process inventory efficiency.http://archive.org/details/improvedviationr1094531922NANAU.S. Navy (U.S.N.) authors.Approved for public release; distribution is unlimited