Tokyo-based Mitsui has agreed to help General Electric finance development of the GE9X engine, a 100,000lb-thrust-class powerplant for Boeing's proposed 777X widebody.
GE Aviation and Mitsui's "strategic partnership" grants the financier interest in the engine production programme in return for the investment at the development stage. Mitsui also agreed to acquire GE engines to offer on the leasing market.
The two firms are also discussing a role for Mitsui's consultancy services to support GE Aviation's business in Japan, according to Mitsui.
The new partnership with GE Aviation broadens Mitsui's growing interests in the aviation business. Last year, Mitsui established Dublin-based Willis Mitsui Engine Support, which leases aircraft engines.
Boeing plans to introduce a re-engined and possibly re-winged 777X later this decade or early in the next decade. GE, Rolls-Royce and Pratt & Whitney are developing engines to power the aircraft.
The 777s in production today are powered exclusively by the GE90 engine.