The sale of its 50 percent interest will be to Turbomeca of France, a member of the Safran group, Rolls-Royce said.
Turbomeca is progressively buying Rolls-Royce shares and will eventually hold sole interest in the program. The deal is worth a total of about $382.5 million in cash.
The sale is expected to be complete before the end of this year, subject to closing conditions.
"Turbomeca will assume full responsibility for the design, production and support of the RTM322 engine, which powers the Apache, EH101 Merlin and NH90 helicopters," Rolls-Royce said. "Rolls-Royce will provide full assistance to Turbomeca during the multi-year transition period to ensure all RTM322 customers continue to receive effective support."
The RRTM Adour engine program which powers the Hawk and Jaguar aircraft, is unaffected by this agreement.