The TATEM project investigates 'Technologies and Techniques for New Maintenance Concepts'. The project was born from a need to reduce the cost of maintenance in the face of increasing sophistication in aircraft and aircraft systems. It brings together a consortium of 58 contractors from 12 countries across Europe, Israel and Australia. The project was led by Smiths Aerospace Electronic Systems, Cheltenham.
Maintenance activities can account for as much as 20% of an operator's direct operating costs and have remained at this level for many years. However, there is scope for increasing the efficiency of the maintenance process. For example, it is estimated that line mechanics spend 30% of their time trying to access information to diagnose and rectify failures, and errors in the maintenance process can impact on aircraft safety. In a recent survey, the incidence of human error during maintenance tasks has been estimated to contribute to 15% of aircraft accidents. The occurrence of the need for unscheduled maintenance can introduce costly delays and cancellations if the problem cannot be rectified in a timely manner.
The objective of the TATEM project was to develop and validate philosophies, technologies and techniques, which can be used to transfer unscheduled maintenance to scheduled maintenance. By taking this approach, the projects aimed to show the means to achieve a 20% reduction in airline operating costs within ten years and a 50% reduction over 20 years.
For the industrial contractors, a successful outcome of the project's objective would potentially yield new ways of doing business, and provide radical changes to aircraft operation and maintenance philosophy, new product opportunities and the formation of new partnerships and collaboration. The academic contractors supported these outcomes by significantly contributing to the scientific and intellectual challenges of the project.
Maintenance engineers often work under severe time pressure on complex problems and in difficult physical conditions, which requires access to detailed information to diagnose and repair problems. Such factors mean that effective research into aircraft maintenance must take a multidisciplinary approach to address the technical and human related challenges.
TATEM took a holistic view towards maintenance across the aircraft and investigates all aspects of 'on-aircraft' and 'off-aircraft' maintenance issues. The technical focus of the project was to assess the following maintenance philosophies, technologies and techniques:
- maintenance-free avionics that require no scheduled maintenance work;
- signal processing techniques (e.g. fuzzy logic, neural networks, model-based reasoning), which can be used to convert data into information about the health of the systems;
- novel on-board sensor technology to gather data from the aircraft (avionics, utilities, actuation, engines and structures), to feed prognostic or diagnostic systems;
- diagnostic methods to identify and locate failures and malfunctions and so reduce the incidence of 'no fault found' alarms;
- prognostic methods to provide support for preventative maintenance actions;
- decision support techniques to generate process-orientated information and guidance (instructions) for the maintenance engineer;
- human interface technologies to provide the ground crew with information, data and advice at the point of work;
The aim in the first year of the project has been to understand the strengths and weaknesses of the current maintenance 'approach'. The aim in years 2 and 3 of the project was to develop the maintenance philosophies, technologies and techniques that can achieve the desired cost reductions. The most promising of these were integrated into a large physical demonstration(s) in the fourth year of the project. This provided the means for validating whether the project has been successful in its aims of reducing maintenance costs.
TATEM has taken important steps in demonstrating the key technical, cultural, commercial and infrastructure capabilities that will underpin service provision in a future health managed enterprise is ongoing. The TATEM project has shown that it is technically feasible and the challenge going forward is to build upon this and others successes to realise the promise of new enterprise and operational solutions. New services and products are emerging to satisfy the growing demand of both military and commercial customers. Customers are keen to embrace more sophisticated contracting regimes for larger and more complex systems.
- Developing open standards and protocols for support functions will be essential for market penetration and customer acceptance. Successful solutions will offer integration across the value chain.
- Gaining an understanding of the interactions (intended or otherwise) of complex systems can be as important as monitoring individual equipment or sub-systems. This is an area of work that requires serious attention if the full capability of aircraft health management is to be unlocked.
- Managing the technical complexity of the interactions of people, organisations, technology, policy and economics remains one of the biggest challenges in deploying a future health managed enterprise.
- The key to success is the acquisition, exploitation and management of data.
- The first part of the TATEM project analysed current maintenance practices and identify major weaknesses and strengths. In parallel the project developed a shared understanding of operators and MROs operational needs.
- Based on these investigations the project is confident that the TATEM concepts are strong enablers to achievement of these operational needs.
As a result of the studies on diagnostic and prognostic methods for the Uplock actuator, a new method of signal-based fault detection was developed. The combination of basic wavelet features and Support Vector Classification resulted in an highly flexible and powerful statistical method for detection of transient and stationary signal characteristics.
The work on the GEMA actuator enabled the implementation and validation of an estimation library with focus on hybrid systems. Further, the separation of external disturbances and internal failures was validated through simulation experiments.
Based on real in-flight measurements, a sound statistics of usage profiles for primary flight control actuators was derived. This can be used as a-priory information on fault detectability regarding flight phases to increase the integrity of the diagnostic system. A generic concept of fault diagnosability was proposed which utilises the hybrid system methodology.
A demonstrator for fully immersive VR maintenance training was developed. The demonstrator can be used to train a landing gear brake removal procedure. Innovative is the inclusion of a 'change place' functionality. This allows the trainee to easily change his location in the VR environment. This allows him to play multiple roles of different technicians. By this, technical interrelations between the different locations are made visible and memorable.
TATEM provided the first opportunity to highlight the importance of a wider understanding of human factors in order to develop and successfully introduce technological innovations. However, as the sample analysis have shown, not all issues arising out of new technological developments, both problems in implementing them as well as opportunities to improve process within an sector of the industry, can be covered at the technology level alone. Some of these issues require structural changes in the organisational set up of companies or even a whole industry.