Aircraft have very long lifecycles. The time that elapses between the first draft for a new program of aircraft and the end of life of the last aircraft delivered can be as long as 80 years. The data defined for archiving and retrieval must be made available throughout the product lifecycle in a standardized format that can be read and reused regardless of any changes made to the original IT environment. Ensuring this is the objective of LOTAR.
LOTAR is a project that is being carried out under the joint auspices of the AIA, ASD-Stan, PDES, Inc. and the prostep ivip Association. Its objective is developing, implementing, testing, piloting, publishing and maintaining standards for the long-term archiving and retrieval of digital product and technical information. This includes CAD and PDM data, composites, wire harnesses, MBSE artifacts and CAE simulation data. The multi-part standard describes both the information content and the processes required to record, store, manage and access information. The documents are published as part of the EN/NAS-9300 series of standards.
The fundamentals and general processes provide the foundation for LOTAR. They are based on the ISO 14721 OAIS reference model, which has been extended to include the requirements of the aerospace industry. To accommodate the growing scope of the project, the work group responsible for the project reworked the LOTAR structure (Part 001) in 2022 and submitted the new document for publication together with the third edition of terms and references (Part 007).
The work group Mechanical 3D CAD with Product and Manufacturing Information (PMI) revised the common concepts for 3D mechanical CAD information (Part 100) to reflect the further development of CAD methods and systems in recent years. This also makes it easier to reference and verify LOTAR traceability requirements during a corporate audit. A first pilot project involving PMI at assembly level and based on STEP AP242 XML was launched.
The PDM work group validated the STEP mappings for the product data in the design stage ("As designed"; Part 210) and in the planning stage ("As Planned"; Part 230) and prepared Part 210 for voting on external publication; this is to take place during the course of the current year. A key focus of the work performed by the work group was coordinating requirements with other domains, such as CAD and MBSE. It finalized the description of common use cases including the relationships between alternative and spare parts, validation properties and PDM viewer requirements together with the PDM IF.
The Composites work group defined PMI requirements for composites including limited length and application indicators (LLAI). It also discussed the need for data standards to support the use of composite data in downstream manufacturing and NC processes and reviewed the requirements for AP242 Edition 4.
The objective of the work group is to determine and maintain the data required for the definition of a wire harness. The design and analysis processes must include both electrical (ECAD) and mechanical (MCAD) data. The group agreed on a uniform view of the key information for wire harnesses and defined an approach for integrating ECAD and MCAD, using the AP242 Domain Model to maintain design and analysis data.
The work group's activities focus on developing standards for general MBSE archiving (Part 500) and for archiving simulation/analysis models (Part 520). The use cases for archiving simulation/analysis models were expanded on the basis of the results delivered by prototypes. They describe a reliable process for linking requirements with a simulation model, an improved workflow and a formal process for determining validation criteria. The work group coordinated the results with other consortia including the prostep ivip Association, NAFEMS, INCOSE, AFNeT, A&D_PLMAG and OMG.
The creation of standards for long-term archiving requires both technical and archiving-specific know-how. The difficulty here lies in the fact that the resources of the member company are limited and the experts are often involved in more than one LOTAR work group. This has led to delays in some work groups, which has slowed progress. From a more technical point of view, challenges arose from the fact that the design methods, tools and data for model-based approaches are in many cases not yet fully mature and the corresponding target standards such as AP242 Edition 4 and χMCFare still being developed.
Plans for the current year include new versions of LOTAR Fundamentals and Concepts (Part 003) and other process parts. In the context of PMI, it is intended that the parts involving CAD geometry data with graphical and semantic PMI and CAD assembly structure be revised. In addition, the work group will start documenting the requirements for archiving CAD assembly structures with semantic PMI as Part 126.
The PDM work group intends to review the diagrams and process charts for product data in the planning stage "As Planned" and prepare Part 230 for voting on external publication. It also intends to propose that the technical specification for validation properties be updated and published as LOTAR Part 205. The work group responsible for composites will finalize the fundamentals and concepts for archiving composite design data (Part 300) and make proposals for expanding STEP AP242 Edition 4.
The Electrical Harness work group's objective for the current year is to publish a solution for archiving electrical design data and, in particular, for archiving physical wire harnesses for design and construction (Part 410). The MBSE work group will publish the fundamentals and concepts for the long-term archiving of model-based systems engineering information (Part 500) and for the archiving of analytical models (Part 520). It also aims to demonstrate the content of MBSE archive packages and the workflow for archiving and retrieval using publicly accessible test models, real authoring tools and newly developed tool prototypes.
"The fact that face-to-face meetings were once again possible last year had a significant impact on the progress of the LOTAR project. From the point of view of project coordination, it was particularly gratifying that we were able to revise and improve the process for coordinating LOTAR documents with AIA and ASD. This will speed up their publication as EN/NAS standards significantly."
"This year, we would like to revive the Engineering Analysis work group, which deals with archiving CAE simulations. We hope that the project partners will make the necessary resources available. We would also like to gain new project partners who are interested in topics like electrics/electronics and the long-term archiving of embedded software."