Innovative industrial resources, techniques and methods have been used to meet the very tight development lead times for the EC175, without compromising the future performance of the helicopter.

The industrial task sharing between Eurocopter and China has allocated each sub-system to one of the two partners. Under this system, the suspension, rotor shaft module, tail rotor components and main gearbox (MGB) have all been entrusted to Eurocopter’s teams.
“The MGB was our biggest challenge,” confides Benoît Klein, the man in charge of organising the industrial scale production of the EC175’s dynamic components. “We were up against a very tight development schedule.”
It took approximately ten years to develop the transmission systems for the Tiger, and five for those of the NH90. But two years is all that will be required for the EC175, thanks to the use of highly innovative engineering and manufacturing methods.
“For the very first time, the MGB, the gears and the casing were completely developed using Catia V5,” continues Benoît Klein. “This digitisation offers a very high level of precision which allowed us to assemble the 3,000 components in a week, instead of the two months we had initially estimated. According to the fitters, the MGB assembly went like clockwork.” In addition to the thermal and mechanical models, the digitisation was also used to simulate the trials performed on the test bench well in advance. “We deliberately made the level of quality of the parts very high to ensure the smoothest possible transition to production,” Benoît Klein explains.
The highly advanced co-engineering also generated very significant time savings: the production department used the reliable information provided by the design office to launch the manufacture of the parts before their drawings were completely frozen.

World firsts
The use of the most sophisticated technology on the MGB will also guarantee very high performance levels. The ball bearings have integrated races, and widespread use was made of magnesium alloy with an HAE protection against corrosion, and the deep nitriding process.
This technology, which offers an excellent weight-topower ratio, was first used on the Super Puma and Tiger in the early 1990s. On the EC175, it is applied to the entire drive system, further offering exceptional performance in terms of power transmission and the ability to run the MGB without oil in emergencies. The final stage of the power transmission has also benefited from a quiet planetary gear train, which has considerably reduced the levels of noise inside the cabin and outside the helicopter.
“Major industrial resources have been put at our disposal to drive this policy of innovation,” continues Benoît Klein, citing such examples as “the deposition of tungsten carbide by thermal projection to improve the contact between the parts, and the widespread use of electron beam welding and 5-axis machine tools.” Just as important is the centre’s mastery of the Spiro and Gage software programmes, which are essential to the cutting and grinding of gear teeth; or even the installation of a complete production line for the planet gears, from the blank up to the final manufacturing.

Hand-over
The picture would not be complete, however, without mentioning the human dimension behind the policy of innovation that is specific to the EC175. “Perhaps the biggest challenge for this programme was the transfer of knowledge between the generations,” concludes Benoît Klein.
“Being able to control the development stage and the organisation of the industrial scale production is the only way of introducing a new gearbox and ensuring the long-term future of this know-how. We often placed two people together at each station so that a young engineer could work side-by-side with a specialist. In case of doubt, the latter could validate the technical decisions made by the former. This expertise has now been preserved for the years ahead.”