Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS


EXPECT Informe resumido

Project ID: 270573
Financiado con arreglo a: FP7-JTI
País: France

Periodic Report Summary 1 - EXPECT (Examination of Practical Aspects of Innovative Bonded Composite Repair Techniques)

Project Context and Objectives:

Even though adhesively bonded composite repairs exhibit significant advantages in terms of mechanical efficiency compared to mechanically fastened ones, they are at the same time extremely sensitive to process parameters variations. Small deviations against the repair specifications (e.g. surface preparation) may lead to disproportionally larger consequences to the final mechanical performance of the repair and, consequently, to the integrity of the structure, compared to mechanical ones. Moreover, the inevitable differences between laboratory and repair shop conditions, may lead to the cancellation of promising technological achievements for “practical” reasons, in case the required conditions could not be easily met in standard practice.

The scope of this proposal is to examine, from a practical application point of view, the innovations achieved within Task 1.3.6-02 of the GRA ITD for bonded composite repairs, in order to facilitate their transfer to production conditions. For this reason, the whole chain of process steps which have to be followed for the performance of a typical repair (i.e. surface preparation, patch lay-up, high temperature curing and Non Destructive Testing etc.) will be executed in standard repair shop conditions, in terms of facilities, equipment, tooling and personnel training. Potential contradictions of innovations developed by the GRA ITD to standard repair practices will be identified and alternative solutions will be proposed, to facilitate their efficient transfer to production standards and requirements. Finally, the practical applicability of the new methodology will be demonstrated, by performing repairs to larger panels, within the frame of WP1.3.7 of the GRA ITD.

The main steps which need to be followed for the performance of a “typical” repair to a composite structure, generally include:

a. Initial Non Destructive Testing (NDT) of the damaged area, in order to define in detail the external borders of the damage.
b. Removal of the damaged composite material by cutting, drilling and milling, in order to get a scarfed or stepped configuration.
c. Composite patch preparation (lay-up) / application (preparation of vacuum bagging and application of heat)
d. Final NDT of the repair, to identify potential debondings, delaminations, moisture, foreign inclusions or other anomalies.

In order to enable the performance of these repair steps in situ, a series of special portable equipment has been developed, fulfilling the repair specifications requirements and overcoming the numerous constraints of repair performance within hangars or repair workshops.

The main concept driving this proposal is to perform the whole chain of required steps for the performance of typical composite repairs, as listed above, using the same equipment existing in repair workshops of airline companies and MROs, and applying the same conditions / constraints (environmental, personnel training level etc.) usually existing in typical workshops, with the following main objectives: a. To evaluate the performance of bonding strength and examine practical application aspects of bonded composite repairs using innovative materials and, potentially, modified surface preparation processes as developed within the JTI-GRA WPs, along the whole range of repair application procedures (surface preparation of composite substrate (stepped / scarfed), lay-up of the repair patch, curing of the patch and the adhesive at elevated temperature (~120 °C) and NDI.

b. To identify areas of potential contradiction of new processes to existing repair practices and procedures.
c. To propose alternative solutions (changes of procedures, development of special equipment etc.) in order to overcome such potential contradictions / constraints

By applying these steps, the main objective of the proposal will be fulfilled, which is to guarantee that the technological solutions developed within JTI-GRA ITD corresponding WPs will not only work under conditions of academic research, but will also work reliably if applied in commercial aircraft maintenance. The practical applicability of the new methodology will also be demonstrated, by performing repairs to larger panels, within the frame of WP1.3.7 of the GRA ITD.

Project Results:

There were 2 technical Work packages in order to perform the research and development activities of this project, together with 2 additional Work packages supporting the research activities, dealing with dissemination of results and project management. More specifically:

- WP1 contains the definition of the innovative repair process parameters and their elaboration against the process sensitivity factors and constraints. Moreover, an evaluation of the standard equipment appropriateness for the new techniques will be performed, before applying the new technique and assessing its practical application aspects.
- Within WP2, the demonstrator repairs were performed, within the frame of WP1.3.7 of the GRA ITD. Moreover, the documentation of these demonstrator repairs was prepared, based on the overall process evaluation results. The documentation was prepared in two steps, namely an intermediate and a final one. This WP closed with the final evaluation of the practicability of the new methods.
- WP3, dealt with the activities concerning dissemination and exploitation of research results produced within this project, attempting to maximize the knowledge transmitted from this research project to the scientific and the industrial world working on aeronautics. This Work package was considered of top importance, as the overall impact of the project and its effect to the European competitiveness largely depends on it.
- The Project Coordinator, GMI, was mainly responsible for the implementation of WP4, which contained the project management and coordination activities as well as for the prompt periodical reporting towards EU and the “Topic Manager”. Playing a key-role in the project, the Project Coordinator, was responsible for the adequate performance of the required management and coordination activities.

Potential Impact:

Economic growth around the world has led to a continuous increase of air-traffic numbers during the past decades. This increase is expected to continue at an even stronger pace for the next two decades. As the operating fleet grows, the costs and hazard exposure will also increase. Despite the recent difficulties faced by the industry, the market forecast over the next twenty years for commercial aircraft is expected to be of the order of €1.6 Trillion. The Aerospace Market remains a highly competitive one and any aspect of commercial advantage must be sought. EXPECT will address a key element of competitive advantage for the industry, those of aircraft reliability during operation and maintenance costs.

Replying directly to JTI’s call for proposals, the primary drivers for EXPECT relate to safety, economic and societal issues. The application of the proposed advantages to the composite repair process will improve reliability during operation, improve performance and minimise the time the aircraft needs to spend on the ground for repair, which are among the main targets of Cleansky JTI. This will permit increased aircraft availability and lower maintenance costs to be incurred by the operating company. The increase in reliability will lead to a reduction in accidents, loss of life and associated compensation costs resulting from failure of critical aircraft structural components. It is expected that this project will lead to a major change in the development of bonded composite repair procedures, thereby strengthening the EU position within the global Aerospace Market, whilst maintaining the competitive advantage of the EU companies over its US and Chinese rivals.

It is planned that full industrialization of the results of the project, in terms of application of the new processes to various cases where bonded composite repair will be engaged, could take place very shortly after the end of the project, according to the requirements of the “Topic Manager” and CSJU.

3.1.1 Savings Generated as a Result of this Project

Reduced Maintenance Costs:

The inspection of aircraft is carried out during periods of maintenance activity. During this period the aircraft is decommissioned from service. For an Airbus A320 minor checks take place every 600 flight hours for the newly manufactured aircraft and every 500 flight hours for the older ones. Medium planned maintenance normally takes place every 20 months for the new aircraft and every 15 months for the old ones. Major planned maintenance during which the aircraft is taken apart is carried out every 6 years for the new A320 and every 5 years for the old ones. Major planned maintenance can result in aircraft being taken out of service for well over 30 days. According to Airbus in the first 5 years of operation an A320 requires 564 man-hours in maintenance, for 10 years of operation 1,344 man-hours and for 12 years of operation 1,981 man-hours. The total average cost of maintenance for an A320 over a period 15 years is €5.2 million, a significant burden for the operating airline. Total maintenance costs for Europe amount to €615 million per year. The successful implementation of the EXPECT project development is expected to reduce these maintenance, repair and inspection costs significantly. Finally, potential practical applications of the innovative repair processes will concern the new Green Regional Aircraft, leading to significant reduction of maintenance costs and increase of reliability in maintenance.

Contribution to Community Social Objectives

If this project will have no direct impact on employment in the aeronautic sector, it will contribute to the renown of European technology and will induce future related research developments. The project is an applied research project with ambition to provide a technology that can be directly industrialized within the JTI and promoted to the worldwide market of repair stations. It deals with a subject, bonded composite repairs, which is a challenging issue between Europe and USA and where large scale research activities take place worldwide.

a. Employment prospects and level of skills in the EU

The European aerospace industry directly employs some 429 thousand people whilst the second tier suppliers employ a further 500 thousand people. European industry has taken bold steps to use an increasing amount of advanced aerospace materials in their aircraft structures. Consequently, their aircraft have on average considerably more advanced light-weight materials than US suppliers, such as Boeing, making European aircraft significantly lighter than US manufactured aircraft of similar seat capacity. This gives European aircraft manufacturers a considerable competitive advantage over US manufacturers. This advantage is threatened by a loss of confidence in the use of advanced light-weight materials following recent air disasters caused by undetected defects in such components. The results of this project, combined with the overall improvement of bonded composite repairs, are expected to help in restoring confidence in the use of advanced aerospace materials. This will result in safeguarding and increasing the employment prospects in the European aerospace industry.

b. Life extension of aircraft:

This project will deliver technology, which will help in improving safety and operational capability of aircraft, leading to an increase in operational life. The countries of Eastern Europe have ageing air fleets that include 30-35 year old aircraft. In the absence of appropriate techniques to restore their structural integrity and to support life extension programs, these ageing aircraft will need to be decommissioned in the near future to meet EU safety standards. This will seriously affect the East European airlines that are currently struggling to be competitive and survive in the global market. The EU predicts strong growth in the market which could be exploited by airlines that increase the operational life of their aircraft whilst meeting EU safety standards, leading to significantly better returns on investment and profitability. EXPECT will contribute to European wide sustainability and growth, particularly enhancing employment prospects in the new Member States.

c. Level of skill in EU:

This project will lead to an improvement in the level of skills for European citizens, as it will assist in implementing new bonded composite repair processes. The project will help in developing and sustaining EU expertise in these new technologies, with direct positive effects to the level of EU in the global composites market.

d. Environmental impact

Through enabling life extension of existing aircraft structures and improving their structural integrity, as well as by supporting of the Green Regional Aircraft development process, greening of aircraft operation and maintenance is achieved, thus helping in reduction of the environmental impact of aviation. Considering that approximately 600kg of CO2 are emitted per kilowatt hour of energy generated by fossil fuels with existing technology, this significant improvement in maintenance activities is directly matching with the targets of the Cleansky JTI.


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