Development of a mechanical maintenance training simulator in OpenSimulator for F-16 aircraft engines☆
Introduction
At the Portuguese Air Force, engine technicians go through an initial training process at the Centre for Military and Technical Training of the Air Force (CFMTFA, Portuguese-language acronym), and are subsequently placed at different air bases, each with different aircraft, and specific engines and requirements. Thus, at each of these bases, they receive further training, focused on the specific engines and aircraft deployed and serviced there. In the case of the F-16 aircraft, this takes place at Air Base Nr. 5, in Serra do Porto de Urso, near Monte Real, Leiria, Portugal. Since technicians may be re-deployed to other bases, training of technical procedures for maintenance of specific engines is a common and frequent process. The training process has an initial theory phase, based on technical documents known as “Technical Orders” or TOs [1] (Fig. 1). Then an on-the-job training phase ensues, with trainees acting directly on an engine, in actual maintenance circumstances.
This final on-the-job training phase is resource-demanding, since it requires engines to be available either specifically for training or for longer servicing allowing for training to take place, and consequently unavailable for operation. Also, procedure errors, whose risk is greater during training, may in some cases produce costly component damage. Further, several of the technical procedures need to be executed by a team, meaning that time allocation of trainees, trainers, and experienced technicians needs to be managed, in order for a full team to be available for on-the-job training to ensue. These various resource requirements place constraints on the availability of on-the-job training opportunities and emphasize the need to optimize it. The development of a serious game for this scenario, a 3D multi-user mechanical training simulator, aims to provide trainees and trainers with more opportunities to conduct training, with the goal of allowing trainees to reach on-the-job training better prepared and thus to optimize the effectiveness of the resource-intensive training occasions with physical engines. This is a joint effort of the Portuguese Air Force and the University of Trás-os-Montes e Alto Douro (UTAD), which subsequently received the cooperation of the INESC TEC research organization.
The development of such a serious game is a complex software engineering project, requiring technical expertise and a careful balance between design principles and pedagogical content, taking time, resources and teamwork. As serious games become more complex, so do the engineering challenges that arise during their development. A particularly significant challenge in this scenario is that mechanical procedures are constantly evolving: as errors are committed and/or insights developed, the recommended practice is changed, in order to optimize resources and lessen risks. At Air Base 5, this evolution effort is executed under the approach known as lean principles [19].
The consequence for software development is that any mechanical procedures implemented in a simulator are likely to become obsolete rather quickly. Any development costs and resources are further increased by the need to update the simulated procedures. This is now somewhat lessened by employing game engines or development platforms rather than developing from scratch, rendering the early-stage selection of the engine or platform for development critical [2]. Following this software engineering perspective, there is a goal of lessening the resource requirements of both simulation development and updating. Thus we present an approach that focus on tuning and perfecting the simulated operations and behaviors, rather than the visuals. For this purpose, we employed a readily available virtual world platform (OpenSimulator) rather than a game engine; and in order to allow the knowledge embedded in behaviors and operations to be independent from this platform, we implemented control code and decision-making logic as an external system, accessed as a Web Service. The rationale for this architectural choice was to enable the visual and interaction platform to change subsequently, if necessary, but keeping the fast-prototyping benefits of a virtual world platform such as OpenSimulator [3]. In this paper, we present this approach and test its feasibility by submitting the prototype to user tests at the air base, with mechanical maintenance trainers.
Section snippets
Background
F-16 aircraft of the Portuguese Air Force are at the so-called mid-life update version (known as MLU), and employ Pratt & Whitney F100-PW-220/220E engines, with large number of mechanical maintenance procedures – the manufacturer recommends periodical inspections depending on the number of flight hours. Inspection procedures are conducted before and after each flight, and there is also programmed maintenance that takes place every 300 flight hours, with the overwhelming majority of these
System architecture
As mentioned earlier, a key concern in this system is that its operations may need to be changed regularly: while the TOs are the basic reference for maintenance procedures, their actual execution is tuned to improve efficiency or diminish risks, following a perspective of continuous improvement and lean principles [19]. Further, in order to include gaming approaches to training, different pathways, error possibilities, and varying degrees of difficulty may need to be implemented and
Prototype aspects
To develop the system prototype, we expedited the 3D environment modeling using the built-in end-user tools of OpenSimulator/Second Life client viewers, and employed QAvimator to recreate in 3D the movements of the technicians. The goal in this prototype stage was not one of photorealistic visuals, but simply to be credible for testing and development. Following the overall goal of separation of concerns between simulation rendering and software control/decision-making specified in the
Sample simulator tasks
The installation process of a Pratt & Whitney F100 engine in an F-16 aircraft is quite extensive and complex, requiring three technicians to do the various procedures. Plus, a specific role in the process is that of process checker, which may be played by one of the three operating technicians, by may also lead to a fourth person being involved, should none of the three required technicians have the credentials to perform this role. All necessary procedures are specified in a document known as
Settings, preparation, context and testing
In order to evaluate the feasibility of the simulator prototype, to ascertain whether we could pursue this architectural approach and inform its subsequent development, two field tests with prospective users were planned and conducted. Test 1 took place during a 2-day stay at Air Base Nr. 5. An early version of the prototype had been demonstrated earlier to the air base command, but no actual user tests had been conducted then. With this 2-day stay, the team aimed to make the prototype
Settings and conducting testing
After improving the simulator, based on the results of Test 1, we conducted a new field test with prospective users, on July 2nd. The setup, preparation, and physical context was identical to the first test, but this time with the simpler goal of confirming whether new procedures and modified procedures were being provided correctly. Again two sessions took place, involving six trainers, divided into 3-element groups (since 3 technicians is the minimal number for conducting the engine-insertion
Conclusions and future work
The tests confirmed that the selection of a virtual world platform technology (OpenSimulator) and the use of a Web service for control of the simulation is a feasible approach for the development of training simulators for this scenario, considering the use by the actual trainers involved in technician training at the air base. The nature of most omissions in terms of simulation aspects revealed that the procedure analysis needs to be fine-tuned, taking into account tactical know-how and
Acknowledgements
This work is financed by the ERDF – European Regional Development Fund through the COMPETE Programme (operational programme for competitiveness) and by National Funds through the FCT – Fundação para a Ciência e a Tecnologia (Portuguese Foundation for Science and Technology) within project «FCOMP – 01-0124-FEDER-022701». This project has been partially funded with support from the European Commission. This article reflects the views only of the author, and the Commission cannot be held
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This paper has been recommended for acceptance by Bellotti.