Seals for the Airbus GP7000 engine

Citation

Bingen, F. (2004), "Seals for the Airbus GP7000 engine", Aircraft Engineering and Aerospace Technology, Vol. 76 No. 1. https://doi.org/10.1108/aeat.2004.12776aaf.005

Seals for the Airbus GP7000 engine

Seals for the Airbus GP7000 engine

Keywords: Seals, Engines, Aerospace, Aircraft

In early 2003, an agreement was reached between MTU Aero Engines and Sulzer Metco's turbine components unit, through its company Eldim, on a risk and revenue sharing partnership concerning development and series production of the low-pressure turbine (LPT) inner and outer air seal components of the GP7000 engine. This engine will be part of the A380 Airbus aircraft.

Germany's leading engine manufacturer, the Munich-based MTU Aero Engines GmbH, is responsible for the production of the GP7000 high-pressure turbine, as well as for the development and production of the low- pressure turbine and turbine center frame. The GP7000 will be the MTU's most substantial civil-engine program in the next few years. It will have its first run in February 2004 and will enter service on the A380 Airbus during 2006.

Long-lasting partnership agreement

The partnership agreement between MTU and Eldim provides for strategic cooperation in the development of turbine seals and the exchange of knowledge, with Eldim immediately sharing in the development of the GP7000 components.

Within this long-term partnership, Eldim's part concerns the development and production of the outer air seal (OAS) segments in all six LPT rotor stages. In a separate long-term supply contract, the production of the inner air seals in all five LPT stator stages will also be covered. All together, one engine set of outer and inner air seal segments consists of 239 assembled parts.

The GP7000 engine is being developed by an “engine alliance” of Pratt & Whitney and General Electric. Both companies have a 50 per cent share in the alliance and also act as Tier-1 partners. MTU is a Tier-2 partner to Pratt & Whitney, as well as to General Electric.

Experts in turbine seals

The alliance between MTU and Eldim gives advantages to both parties. For MTU, Eldim brings its considerable expertise and experience in the production of high- and low-pressure seals. For Eldim, the partnership offers unique situations, including the volume of work, the duration of the commitment, and MTU's willingness to transfer OAS development technology to Eldim. The latter provides a unique opportunity to increase the company's added value for OEMs by extending the ability to produce seal segments with the ability to also design and qualify these components. Eldim has repeatedly demonstrated its competence to provide design-to-build input in the design process of its customers, resulting in product definition that matches Eldim's production capabilities. However, the competence to understand and apply the rationale behind the design (in terms of geometry, dimensions, and material selection) is an entirely different, and more complex, set of skills.

Close co-operation with MTU

In the aerospace business, the last phase of the design process typically contains a split of activities. One chain of activities is aimed at freezing the configuration of the components as an input to the production process of pre- and series production units. Freezing the configuration is necessary, as various directions are investigated and the design evolves during the process, with the most appropriate configuration as a goal. The product development engineer could continue to evolve the product indefinitely, but the manufacturing engineer requires a stable configuration as a basis for series production. The other chain of activities, which runs in parallel with the production process, is aimed at obtaining airworthiness certification for the components.

Eldim participates in both chains. Co-located in Munich for 3 months, one of Eldim's engineers has already participated in the product definition process of outer and inner air seals. This proved to be very effective and resulted in the timely release of drawings with all relevant design-to-build input incorporated. The process proved the importance of tightly controlled engineering data management and the effects of configuration freeze. The use of computer-aided design tools was practiced, hands-on, and proved its efficiency.

Reverse engineering

The next step is to enter the qualification of the design. Although proper functioning of the seal segments is validated in full-scale engine tests, an analytical validation of sufficient strength stiffness and structural life is also required. It is the intention to have a “reverse engineering” process executed by two product development engineers. Normally, design engineering creates solutions to the given requirements. Reverse engineering works the other way around, by taking the solution, or the defined products, as the goal, and deducing the requirements and design choices from them. Comparison of the results of this process with the actual GP7000 LPT design requirements shows opportunity for design improvement.

Within this process, the engineers will be trained on the job, under supervision of MTU product development engineers and, for that reason, will also spend a considerable amount of time in Munich. Apart from establishing the design rationale behind seal components, these engineers will witness the execution of engine tests and subsequent tear-down of test engines. They will also participate in the process of identification and implementation of design changes that might result from these tests.

The ultimate conclusion of the engine development process is the release of the type certificate, which is scheduled for June 2005. Through this process, Eldim will build-up a track record that will enhance the company's standing as a strategic partner in the aerospace industry.

Details available from: Eldim B.V. Tel: +31 (0) 77 473 19 19; Fax: +31 (0) 77 473 24 85; E-mail: fons.bingen@sulzer.com

Fons BingenSulzer Metco