Research and Technology throughout the Landing Gear Life Cycle
Given the mission-critical nature of their function, landing gear constitute a vital part of an aircraft. The neccesary reliability and robustness required of today’s landing gear must also be balanced against stringent weight and cost reduction drivers. The resulting product must offer excellent in-service performance and optimize total ownership costs acress the life cycle. Backed by the vast technical resource within the SAFRAN group, Messier-Dowty is actively pursuing new opportunities to optimize landing gear technology throughout every stage of the product life cycle.
Modeling and simulation
As a systems integrator, Messier-Dowty employs modeling and simulation during the design phase, in close partnership with the airframer and other landing gear subsystems provided by specialist partners. These techniques use predictive models to evaluate the effectiveness of a new product concept and confirm its compliance with the aircraft specifications.
In addition to achieving reductions in design cycle time, engineers are better able to understand the landing gear system interface with the airframe, thus enhancing the overall design and robustness.
Messier-Dowty is currently sponsoring three major projects in the areas of simulation and modeling. The first involves a pilot project with Georgia Tech University to study the vibration characteristics of landing gear while rolling. Messier-Dowty is the first company within the SAFRAN group to work with Georgia Tech’s Aerospace Systems Design Laboratory, specialized in the development and application of advanced design methods for complex systems. Messier-Dowty is also collaborating with leading rubber specialist Hutchinson in the study of seal systems for landing gear. Researchers are using finite element analysis to evaluate both the mechanical and physical properties of the sealing system and mitigate the problem of seal leakage in landing gear shock absorbers and actuators. Messier-Dowty is also involved in SAFRAN Group’s MAIA program, in partnership with other French agencies, to develop new methods in Advanced Mechanics.
ADVANCED DESIGN
Aero-acoustics
Messier-Dowty is actively participating in various projects to reduce aircraft noise, including SILENCE(R), a program supported by the European Union and coordinated by Snecma.
Until the 1960s, engine noise clearly dominated overall aircraft noise levels; airframe noise was negligible by comparison. However, in the early ’70s the introduction of new engine technologies generated significant noise reduction. As a result, the airframe noise component, including landing gear, became relatively more important.
Messier-Dowty has been heavily involved in the study of landing gear noise reduction since 1998, covering two main phases of activity. The first phase, evaluated on the A340 in 2003, served to identify the noise generating features in order to design and manufacture noise-reducing fairings for flight test evaluation. The second phase, currently underway, involves the investigation of alternative landing gear configurations using noise reduction as a design driver. The end goal is to achieve a landing gear design that inherently includes noise reduction features without the necessity to resort to add-on elements.
More electrical landing gear
Messier-Dowty is currently evaluating electrical solutions to replace traditional hydraulic applications on today’s landing gear. The advantages are clear: optimization of maintenance and system efficiency, which contribute to overall airframe weight reduction. The main areas of focus for Messier-Dowty include landing gear locking, retraction and steering.
Messier-Dowty is currently participating in several research programs on this subject, including a French Civil Aviation Authority (DPAC) study on the A320 nose landing gear in collaboration with Messier-Bugatti. Other developments include a program supported by the French Armament Authority (DGA) and Dassault Aviation to study electrical applications for military aircraft, including UAVs. Messier-Dowty is also actively participating with other SAFRAN group and European companies in the EU-sponsored "Power Optimized Aircraft" project, a program that is studying the increased use of electrical applications for wide-body aircraft.
ADVANCED MANUFACTURING
New Materials
Backed by the vast technical resource within the SAFRAN group, Messier-Dowty is actively pursuing developments in the use of new materials and suface treatments. Traditionally Messier-Dowty has used Ultra High Strength Steels (300M steel) as well as aluminum alloys to manufacture landing gear. The focus for the future is to introduce materials that can meet increasingly stringent weight requirements while maintaining the necessary robustness of a landing gear. This not only includes working to improve performance over existing materials, such as UHTS steels, but expanding the use of titanium for major structural components and introducing composite technologies for certain landing gear components. Messier-Dowty has introduced UHTS, titanium and composite components on recent development programs. The Boeing B787 main landing gear will not only include UHTS components and a titanium slider, but in an industry first, it will also feature organic matrix composite braces.
In the field of metal matrix composites, for the last three years Messier-Dowty has been evaluating components in titanium matrix composites (TMC). It is clear that some of the properties of TMC far exceed the performance of 300M steels and titanium. Currently the high material and manufacturing costs exclude metal matrix composites from applications at this stage, but is clearly an avenue for the future.
New Surface Treatments
Messier-Dowty is currently involved in an industry-wide development of new technologies to replace cadmium and chrome plating with alternative surface treatments. Cadmium is used on various landing gear components to provide protection against corrosion and chrome is used in contact areas to improve friction/wear properties.
In the area of hard chrome replacement, one of Messier-Dowty’s most important initiatives has been the progressive implementation of an HVOF (High Velocity Oxygen Fuel) process. This process uses metal ceramic powder sprayed at very high speeds ( 3000km/h) onto landing gear components, where it consolidates to form a coating resistant to wear and reducing friction. This process is environmentally friendly, eliminating the use of hexavalent chromium products found in the hard chrome plate process.
Messier-Dowty currently employs HVOF on several production programs, including the A380 nose landing gear and the Dassault Falcon 7X landing gear.
In the area of cadmium, Messier-Dowty is currently studying two methods of replacement. The first method involves replacing cadmium with a more environmentally-friendly coating. The second avenue of development involves using materials for certain components that are inherently corrosion-resistant, such as stainless steel or titanium. Messier-Dowty is collaborating with Aubert & Duval on this subject, with the active support of the French DPAC.
In Service Behavior
The ultimate goal of Messier-Dowty’s development efforts is to have a holistic view of landing gear design and development, providing technological solutions which are cost-effective at every stage in the life cycle. New landing gear applications and materials must provide superior performance, but also remain affordable, reliable, easy to use and repair. Messier-Dowty’s extensive customer support network and MRO affiliate, Messier Services, provide important feedback on the operational performance of company products which is directly incorporated into the design and development process. Messier-Dowty’s Toronto facility is currently spearheading a "Health & Usage Monitoring" project, in conjunction with sister company Sagem for all avionics activities. The goal of this project is to more efficiently leverage operations data and improve landing gear performance in service.