Rolls-Royce Plc, the multinational power systems developer, will sell its 50% stake in the RTM322 engine joint venture to its partner, Turbomeca, for a reported €293 million, or roughly $380 million. The RRTM venture has designed, manufactured, and serviced engines for military helicopters, including Apache, AW101 Merlin, and NH90 helicopters – meaning it’s a critical element of the aircraft used by U.K., Japanese, Canadian, German, and other Western European defense forces.

The venture dates to the early 1990s, and records show about 1,500 are in service.

Turbomeca, a manufacturer of gas-turbine turboshaft engines, is a part of France’s Safran S.A. aerospace group. It will assume design, manufacturing, and service for the engines.

“Our partners didn’t want to continue to invest in the development of a line of product that’s outside their core strategy,” according to Safran CEO Jean-Paul Herteman, who called it a promising enterprise. “We wanted to develop the position.”

According to Rolls-Royce, the sale is a product of its decision to narrow its engine development programs.  Earlier it made a decision to sell its interest in the International Aero Engines venture to its partner, United Technologies. It also sold other engine and fuel cell development programs.

The sale will close before the end of this year, and Rolls-Royce said it would provide full assistance to Turbomecanica as its interest is gradually transferred.

The RRTM venture also manufactures the Adour engine, a two-shaft turbofan model that powers helicopter models in use by more than 20 different air forces – in particular the Sepecat Jaguar and BAE Jaguar helicopters. Rolls-Royce said its sale to Turbomeca does not affect the Adour program.