Boeing said it had launched an investigation after an \"engine issue\" hit a test flight of the 787 Dreamliner a day earlier in South Carolina. \"A 787 experienced an engine issue July 28 while undergoing preflight runway testing in North Charleston. Boeing and GE are working closely with the NTSB (National Transportation Safety Board) and are committed to resolving the issue appropriately,\" the aviation giant said in a statement. \"While the investigation is in its early stages, we are unaware of any operational issue that would present concerns about the continued safe operation of in-service 787s powered by GE engines,\" the statement added. Still \"should the investigation determine a need to act, Boeing has the processes in place to take action and will do so appropriately,\" it said. US media reported that a brush fire was set off, apparently by the debris, at the Charleston airport, which had to be shut down for more than an hour. The Wall Street Journal reported that Japan Airlines was the only airline using 787s with the same type of motor, on four aircraft. The report came after All Nippon Airways (ANA) said last week it had to repair five of its Boeing 787 \"Dreamliners\" amid corrosion problems on their Rolls-Royce motors.