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Improved remaining useful life estimations for on-condition parts in aircraft engines
University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. GKN Aerospace Engine Systems. (Produktion och Automatiseringsteknik, Production and Automation Engineering)
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on obtaining better estimates of remaining life for on-condition (OC) parts in aircraft engines. Aircraft engine components are commonly classified into three categories, life-limited parts (LLP), OC-parts and consumables. Engine maintenance typi-cally accounts for 10% to 20% of aircraft-related operating cost. Current methods to esti-mate remaining life for OC parts have been found insufficient and this thesis aims to devel-op a method that obtains better life estimates of OC part. Improved life estimates are es-sential to facilitate more reliable maintenance plans and lower maintenance costs. In the thesis, OC parts that need a better life estimates are identified and suitable prognosis methodologies for estimating the remaining life are presented.

Three papers are appended to the thesis. The first paper lays out the main principles of air-craft engine maintenance and identifies the potential for improving maintenance planning by improving the remaining life estimation for the OC parts. The paper concludes that re-search is needed to find better estimates so that the right amount of maintenance is per-formed at each maintenance occasion.

The second paper describes the aircraft and its engine from a system of system perspective. The aim of the paper is to show that no system is stronger than its weakest part and that there is a potential to increase the availability and readiness of the complete system, the aircraft engine, by introducing better life estimates for OC parts. Furthermore, a review of all engine parts, no matter if they are life-limited or on-condition, which needs to be incor-porated in a replacement model for maintenance optimization, is given. The paper con-cludes that the reliability of the complete aircraft engine would be increased if better life estimates are presented also for the OC parts.

The third paper includes an evolved analysis of the subject and the analysis moves deeper in to a subsystem/module of the engine, the low pressure turbine. The specific subsys-tem/module is further analyzed to show the potential of increased reliability for the subsys-tem/module and the complete system, the aircraft engine, if better life estimates for the OC parts are obtained. Methods on how to estimate remaining life is discussed in this paper. It is stated that life estimates can be based on visual inspections, available testing methods (e.g. non destructive testing ) or new techniques that may be need to be developed based on remaining useful life estimations. To estimate the remaining life for the OC parts well es-tablished prognostic techniques such as physic-based, data-driven, symbolic, hybrid, or context awareness approaches that combine contextual/situation information awareness will be considered.

Place, publisher, year, edition, pages
Skövde: University of Skövde , 2016. , 106 p.
Series
Dissertation Series, 9 (2016)Dissertation Series
Keyword [en]
Aircraft engine maintenance, Reliability, Remaining useful life, On-condition parts, Prognosis
National Category
Information Systems
Research subject
Technology
Identifiers
URN: urn:nbn:se:his:diva-12653ISBN: 978-91-981474-9-0OAI: oai:DiVA.org:his-12653DiVA: diva2:945577
Presentation
2016-05-30, Portalen, Skövde, 13:00 (English)
Opponent
Supervisors
Available from: 2016-08-09 Created: 2016-07-01 Last updated: 2016-08-16Bibliographically approved
List of papers
1. On-Condition Parts versus life limited parts: A trade off in aircraft engines
Open this publication in new window or tab >>On-Condition Parts versus life limited parts: A trade off in aircraft engines
2016 (English)In: Current Trends in Reliability, Availability, Maintainability and Safety: An Industry Perspective / [ed] U. Kumar, A. Ahmadi, A. K. Verma & P. Varde, 2016, 253-262 p.Conference paper (Refereed)
Abstract
Series
, Lecture Notes in Mechanical Engineering, ISSN 2195-4356
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:his:diva-11334 (URN)978-3-319-23597-4 (ISBN)978-3-319-23596-7 (ISBN)
Conference
International conference on reliability, safety and hazard and Advances in Reliability, Maintenance and Safety (ICRESH-ARMS), 1-4 June, 2015, Luleå, Sweden
Available from: 2015-08-11 Created: 2015-08-11 Last updated: 2016-08-17
2. Aircraft engines: A maintenance trade-off in a complex system
Open this publication in new window or tab >>Aircraft engines: A maintenance trade-off in a complex system
2015 (English)Conference paper (Refereed)
Abstract [en]

An aircraft engine is a system of systems with several degrees of complexity. It is important to perform the correct amount of maintenance at each individual maintenance event. A mathematical replacement model is used to ensure that the correct amount of maintenance is performed. However, this paper shows that the reliability of this model could be improved if there were a better way to estimate the life length of on-condition maintained engine parts.

Place, publisher, year, edition, pages
New Dehli: , 2015
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:his:diva-12651 (URN)
Conference
International Conference on Quality, Reliability and Infocom Technology
Available from: 2016-07-01 Created: 2016-07-01 Last updated: 2016-08-09
3. RUL estimation and maintenance optimization for aircraft engines: A system of system approach
Open this publication in new window or tab >>RUL estimation and maintenance optimization for aircraft engines: A system of system approach
2016 (English)In: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348Article in journal (Refereed) Published
Abstract [en]

An aircraft engine is a system of systems with several degrees of complexity. It is important to perform the correct amount of maintenance at each individual maintenance event. A mathematical replacement model is used to ensure that the correct maintenance is performed. The reliability of the results from the mathematical replacement model will be improved if there is a better way to estimate the life length for on-condition engine parts.

Place, publisher, year, edition, pages
Springer, 2016
National Category
Mechanical Engineering
Research subject
Technology
Identifiers
urn:nbn:se:his:diva-12652 (URN)10.1007/s13198-016-0509-0 (DOI)
Available from: 2016-07-01 Created: 2016-07-01 Last updated: 2016-08-18

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