Boeing Co said it plans a two-hour flight of a company-owned 787 airliner on Monday, to be followed by ground and flight certification tests of proposed changes to the 787's lithium ion batteries in coming days.

Monday's flight would be used to validate that all systems on the new airliner - which has been grounded since mid-January after battery failures on two separate aircraft - are working as designed, said Boeing spokesman Marc Birtel. Boeing plans to use Line Number 86, which was built for LOT Polish Airlines.

Once data from the flight had been analyzed, Boeing said it would prepare for a ground and flight demonstration aimed at certifying the company's proposed changes to the battery system, a key step toward getting permission from the Federal Aviation Administration to resume flights of the grounded plane.

"The plan is to conduct one certification demonstration flight. That flight, which will take place on Line 86, will demonstrate that the new battery system performs as intended during flight conditions," Birtel said in a statement.

Separately, the U.S. National Transportation Safety Board on Monday said it would hold a two-day forum April 11-12 to examine the design and performance of lithium-ion batteries in transportation - a comprehensive review sparked by battery failures on two Boeing Co 787 Dreamliners in January.

The public forum will examine the design and development of various lithium-ion batteries, how their use and manufacturing are regulated, and the use and safety of such batteries in various modes of transportation.

The U.S. Federal Aviation Administration grounded all 50 Boeing 787s in use worldwide in January after failures of two batteries on two separate aircraf - one parked at the Boston airport, and the other forced to make an emergency landing in Japan.

(Reporting By Andrea Shalal-Esa; Editing by Gerald E. McCormick)