EC 175 main gearbox takes shape

Eurocopter design engineers continue ground testing the main gearbox of the EC 175 medium twin. “Trials started in Marignane, France late last year–on time,” program manager Francis Combes told AIN. The company has allotted two years to main gearbox development.

Benoît Klein, head of dynamic component production, said the company created a digital mockup of the gearbox, which saved it a good deal of time. “For the first time, the main gearbox, gears and casing were completely developed using Catia v5,” he said. The 3,000 components were assembled in a week, instead of the two months the company originally estimated.

Combes said the company’s use of concurrent engineering drastically shortened the design phase by allowing all the teams–design, computing, production, quality, supply chain and tests–involved in the main gearbox program to work together. “For example, production people could point out that one design is easier to machine than another,” Combes explained.

The main gearbox of the EC 175 features integrated parts, such as ball bearings with integrated races, thereby reducing volume and weight. While not entirely new, this approach undergoes improvements with every new design it is applied to, Combes noted. Separately, the shape of the gear’s teeth has been reworked to reduce cabin noise. (See 'OEMs: airframe mods key to noise reduction')

Those parts manufactured from magnesium alloy–a material used for its lightness–have received HAE corrosion protection. The deep nitriding process was used to harden surfaces–especially important with integrated parts in which layers of metal are thicker, Combes said.

Eurocopter and its partner, China-based Harbin Aircraft, expect the EC 175 to fly next year.