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·Aeronautics and Aerospace | A Maintenance Information / Management System Applied to Production Automated Eddy Current Inspection Systems at Various Locations
Carlos Pairazaman,
Customer site support, Manager for Veridian Engineering, Oklahoma City, Oklahoma, USA
Sara Keller ,
Branch Chief, Processing Engineering, United States Air Force, Tinker Air Force Base, Oklahoma, USA
Jim Earnest and John Wiegmann ,
Customer site support, Software Engineers, Veridian Engineering, Oklahoma City, Oklahoma, USA
William Martin,
Customer site support, Project Manager for Veridian Engineering, Oklahoma City, Oklahoma, USA
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Abstract
Fully automated eddy current inspection systems have been applied to the validation of continuing structural integrity of gas turbine engine (jet engine) components at various locations throughout the world. The integrated system is identified as the RFC (Retirement for Cause) system and has been implemented as a part of damage tolerance and life extension management system based on materials properties and part usage. The complexity, precision and requirements for quantitative inspection / measurement demand rigid diagnostics and RFC system process control. Management of multiple systems operating in parallel provides an opportunity for anticipating maintenance based on the knowledge and information gained in the use and breakdown / repair incidents for single systems. Maintenance records for each machine are maintained and reviewed to anticipate wear, maintenance and replacement of life limited components. Such records have traditionally been provided in manual form and summarized on a periodic (usually monthly) basis.
Recent RFC system improvements have included integration of maintenance records into the computer based control system to enable record summary and automated search in near real time. The system provides for access to operating data associated with the maintenance tasks and more uniform manual inputs of key parameters, details of diagnostics and maintenance actions. Planned implementation includes linking (via the Internet) all operating site throughout the world to provide improved site support and advanced shipment of anticipated replacement components.
Details of the parameters reported and examples of summary maintenance reports will be presented.
INTRODUCTION:
A fully automated eddy current inspection (Retirement for Cause - RFC) system has been developed, produced and implemented for the inspection of gas turbine engine components at various locations. The RFC system was conceived as a fully automated inspection system that could be operated by mechanics in the engine overhaul facilities. Extensive sub component development and testing were completed to assure that the basic inspection capabilities could be met. The sub components were then integrated into the fully automated system and further system level testing and validation was completed before each inspection sequence (scan plan) was accepted for production application. These practices and disciplines have extended to all subsequent system versions and improvement packages.
The resulting is computer -controlled eddy current inspection station with standard communication interfaces, and extensive computer capabilities. Mechanical scanners provide a 7-axis automated scanning of complex engine part geometries; automated probe positioning and changing to enable inspection of multiple features; and set-up "calibration" reference artifacts for automated NDE set-up and diagnostics.
The system provided inspection of simple geometries (holes, radius areas, slots, etc.) in initial applications, but has been extended to complex geometries and part types. The flexibility in growth has been enabled by the precision of the system robot and by the addition of articulated probe assemblies. The success for the program has resulted in extension to other engines (both military and commercial) and the incorporation of improvements to implement new technology and improved system components. Figure 1., shows a Version 3 system with an engine disk in the inspection fixture.
Fig 1: An RFC Version 3, work station with a mounted engine component.
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Fig 2: Multiple RFC workstations at a gas turbine engine overhaul facility.
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Multiple workstations provide a facility capability for inspection of multiple components and component features with data control and central data storage in a central system computer. All inspection routines (Scan Plans) are stored in the central computer and are downloaded to each workstation when the operator identifies the part to be inspected. The central control and data storage provides a convenient mechanism for software configuration control and provides a central database for a permanent record of all inspections completed. Figure 2, shows multiple workstations at a gas turbine engine overhaul facility.
DISCUSSION:
In addition to providing an automated inspection capability, central storage of inspection data provides a practical opportunity for tracking and analysis of maintenance data and therefor an added dimension in engine life cycle management. Since inspection parameters and inspection mode configuration information are recorded for each inspection sequence, the system provides a database for diagnostics and life-cycle management of RFC system components. Recovery, analysis and use of such information has been termed "DATA MINING" and is a valuable by product of the automated inspection system. This paper is devoted to the "DATA MINING" capabilities and potential for life-cycle maintenance of the RFC inspection system components.
The complexity, precision and requirements for consistent / reliable quantitative inspection / measurement demand rigid diagnostics as a part of the RFC system process control. Management of multiple systems at diverse locations has been a traditional challenge in anticipating required maintenance and providing spares to maintain system availability and through-put. The availability of operating parameters and diagnostic records for each system provide a unique capability for knowledge based "health monitoring". Maintenance needs are anticipated based on the knowledge and information gained in system used and the historical database of breakdown / repair incidents for single systems. Such records have traditionally been provided in manual form and summarized on a periodic basis (usually monthly). The reporting function has been readily automated for the RFC system. The information gained has been incorporated into diagnostic, trouble shooting, repair instructions and in providing spares for those components that are subject to wear, damage, replacement and rework.
For example, a workstation that requires multiple trails during the set-up /"calibration" may have a probe that is worn near its configuration limit; may have worn bearings in the robot arm; or may be indicating a test component that is near the limit of inspection tolerances. Trend monitoring of each machine enables prediction of the most likely functional variance and anticipates the need for remedial action. An additional dimension for diagnostics and anticipated maintenance is provided during periodic workstation performance validation using a "master gage" component that contains known slots / artifacts at various locations. The "master gage" component revalidates the coverage of all areas inspected by a given scan plan and responses to the artifacts provides a measure of the reproducibility and off-set of the work station in comparison to other work stations operating with the same scan plans. Data from the work station validation may be a primary indicator of work station condition and anticipated maintenance requirements.
The advent and implementation of the "INTERNET" has opened up a multitude of opportunities for system diagnosis and communication at remote locations. The communication features have revolutionized heath care and will revolutionize life-cycle maintenance of complex engineering systems as the technology becomes affordable. The availability of diagnostic and maintenance data in digital form has enabled early implementation of the technology and practices in the RFC system. Such capabilities have been incorporated at the same time as the implementation of new technology and upgraded components to provide increased capability at a reduced system cost. Version 4 of the RFC system has upgraded eddy current, upgraded computer, upgraded robotics and upgraded system operating software that has enabled reduction of the system to one bay in physical size while increasing both capability and through-put.
SUMMARY:
Fully automated inspection has been a continuing technology challenge in the production, maintenance and overhaul of modern engineering systems. The RFC system was implemented in 1982 for the inspection of gas turbine engine components and has enjoyed both increased system reliability and a 25 to 1 pay back on the cost of system development. During the past twenty years of operation, continuous improvements and capabilities have been added to the system. Twenty years of engine inspection records and RFC operational system diagnostics have provided a unique database and capability for both engine maintenance diagnostics and RFC system diagnostics / life-cycle maintenance. RFC system maintenance records provide a unique capability for management of system maintenance, repair and spares (replacements) at multiple sites. The combined capabilities provide a test bed for knowledge based health monitoring and knowledge based life-cycle maintenance.
Fig 2: