Boeing Co. of the United States recently suggested it will provide Korea with an F-15 fighter for free, apparently in compensation for the crash of an F-15 fighter off the southeast coast in 2006, a military source said Sunday (Jan. 20).The F-15 fighter jet crashed off Pohang, Gyeongsangnam-do (province), in June 2006, killing its two pilots. Investigators found no engine failure or other technical problems, but suspicions lingered as they only analyzed the wreckage, such as its warning and navigation systems and data on the jet's past repair and flight records.The proposal by Boeing came as Korea revealed last year its plan to purchase from 2014 to 2019 about 60 fifth-generation stealth fighter jets such as the F-22 and F-35 of Lockheed Martin.It also comes on the heels of the U.S. Air Force having grounded all of its F-15 fighter jets last year because of worries over a possible structural failure of the model after a plane crash in Missouri."A senior Boeing official proposed to provide Korea with an additional F-15 fighter jet as we were engaging in negotiations for the purchase of 20 more F-15 fighters," the source said.Korea has so far bought 30 F-15 fighters from Boeing under the contract for purchase of 40 F-15 fighter jets by the end of 2008. Seoul is currently negotiating with the U.S. airplane manufacturer to buy 20 more fighters."Boeing might have made the proposal to express their thanks to the Korean government for its decision to purchase 20 more F-15 fighters," a source said. "The Korean government may make a decision on the proposal late this month when the negotiations for the purchase of engines are to be concluded."Korea has already completed a contract for the purchase of F-15 fighters at around 100 billion won per unit, except for engine, and negotiations are still under way for engine purchase.