(Recasts, adds confirmation of flight test, adds background)
By Tim Hepher
PARIS, Oct 9 (Reuters) - Transatlantic aero engine joint venture CFM International said on Thursday it had begun flight trials of its next-generation LEAP engine, stepping up a race for billions of dollars of jet engine sales in the coming years.
The company, co-owned by General Electric and France's Safran, said in a statement it was on track to win safety approval for the first two versions of the engine in 2015.
Confirming an earlier Reuters report, CFM said it began testing the first engine on a modified Boeing 747 on October 6.
"The engine behaved well" during the three-hour flight over California, CFM International said in a statement.
The LEAP engine is one of two powerplants whose development has galvanised the aerospace industry in recent years as their much-improved fuel efficiency triggered a huge jump in plane sales and pushed anticipated production rates to record levels.
Both CFM and rival Pratt & Whitney, a subsidiary of United Technologies, say their engines will produce double-digit percentage fuel savings for cash-pinched airlines.
The engine developments are at the centre of a struggle between engine makers that easily matches the more visible order race between plane giants Airbus and Boeing.
Pratt & Whitney, which once dominated the industry only to see its civil market share decline in the 1980s, is gambling on new geared turbofan technology to restore its position.
CFM aims to cement its role as the biggest-volume seller of jet engines, 40 years after it was born out of a decision to cooperate by U.S. President Richard Nixon and French counterpart Georges Pompidou.
Both companies have sold thousands of the new engines, but industry sources say each has suffered some glitches in testing.
The development of the two latest engines has meanwhile been felt right across the aerospace industry.
New market entrants in China, Russia, Canada and elsewhere picked the engines to add further efficiencies to their plane designs as they sought to challenge Airbus and Boeing for a slice of the $100 billion annual jetliner market.
But Airbus and Boeing responded by upgrading their own best-selling jets to use similar engines, prompting the vast majority of airlines to stick with familiar benchmark models and triggering a record wave of orders in the past three years.
Industry sources said earlier the engine involved in this week's initial flight trials was a variant known as LEAP-1C, which is being developed for China's new C919 jetliner.
The early tests will be closely watched not only by Chinese planemaker Comac, but also by Europe's Airbus, which plans to use an almost identical variant, the LEAP-1A, as one of the choices for its upgraded A320neo aircraft.
An Airbus A320neo, powered by the alternative Pratt & Whitney engine, took to the skies for the first time last month.
The LEAP-powered version of A320neo is expected to enter service some six months behind the Pratt & Whitney version in mid-2016, but CFM says it has a greater share of engine orders.
Boeing's upgraded 737 MAX uses a variant of the LEAP engine known as LEAP-1B, maintaining an exclusive supply deal between the CFM venture and Boeing's most popular model.
Flight testing is used to expose the engines to extreme conditions and validate test results carried out in ground rigs.
The LEAP-1B version for Boeing will start flying in early 2015, followed by certification about a year later and entry into service in the second-half of 2017, industry sources said. (Editing by David Clarke)