(Adds detail from Pratt in paragraph four)
By Andrea Shalal
WASHINGTON, Feb 5 (Reuters) - The Pentagon's plans to fund 50 percent more F-35 fighter jets in fiscal 2016 will help drive down the price of the new plane and its engine, a top official at engine maker Pratt & Whitney, a unit of United Technologies Corp, said on Thursday.
Bennett Croswell, president of Pratt's military engines division, said the company had submitted a proposal for the ninth and tenth batches of engines to the F-35 program office, and he hoped to sign those agreements by the end of 2015.
The previous two production agreements lowered the cost of the engine by nearly 8 percent, Croswell said, noting that further reductions were planned for the contracts now under discussion - 60 engines in the ninth batch and 100 in the tenth.
Pratt said it has cut the cost of the F135 engine by 55 percent since its first delivery.
The U.S. government signs separate production agreements with Lockheed Martin Corp, which builds the plane, and Pratt, which builds the engine. The Pentagon plans to spend nearly $400 billion to develop and build 2,457 of the radar-evading warplanes over the next two decades.
Croswell welcomed the start of a long-delayed increase in production of the F-35 in the fiscal 2016 budget, which funds 57 jets after 38 a year earlier, and said it would help Pratt, Lockheed and other key suppliers drive down the plane's cost.
Pratt and Rolls-Royce Holdings Plc, which makes the lift fan for the F-35 B-model, are finalizing plans for further reducing the engine's cost, Croswell said. He gave no details.
Lockheed and the other key suppliers for the airframe - Northrop Grumman Corp and BAE Systems Plc -launched a similar effort last summer, which maps out specific investments to reduce the cost to build and repair the planes.
Croswell said Pratt had also developed plans to upgrade the F135 engine in two separate phases.
If the Pentagon accepts and funds the plans, the first upgrades would begin in 2017 or 2018 and reduce the fuel burn of the engine by 5 to 7 percent, Croswell said. The next upgrades would begin around 2022, cutting fuel burn by a further 15 to 20 percent.
The upgrades draw on research work funded by the Air Force and the Navy in recent years. The Air Force included funding for more work on a next-generation engine in its 2016 budget plan. (Editing by Lisa Shumaker and Muralikumar Anantharaman)