( CNN ) -- Passengers from a United Airlines 787 Dreamliner that made an unscheduled landing in Seattle were expected to resume their journey to Japan on Wednesday morning . Flight 139 from Denver to Tokyo was diverted to Seattle on Tuesday afternoon `` due to an indication of a problem with an oil filter , '' United said in a statement to CNN . The aircraft landed normally , said spokeswoman Mary Ryan . The plane 's 210 passengers were asked to stay overnight in Seattle . Coverage from CNN affiliate KIRO . The incident comes five months after the FAA and other officials grounded the Dreamliner worldwide due to troubles with its battery system . In April , the FAA ordered all 787 operators to make specific modifications and United has been flying its fleet of six 787s since May 20 . In an apparent show of confidence in the new airliner , United announced Tuesday it was ordering 20 additional Dreamliners -- specifically the 787-10 model , which is a longer version of the plane . Chris Seewald tweeted that he was a passenger on Tuesday 's diverted flight . He said the aircraft 's pilot told passengers that the `` engine was not operating optimally . '' Seewald also tweeted a photo that he said showed the Dreamliner dumping fuel before landing in Seattle . Coverage from CNN affiliate KING . The 787 Dreamliner began service in the U.S. in 2012 . With a fleet of six , United is the sole domestic operator of the airplane , which boasts high fuel efficiency due to the light-weight carbon-composite materials used in its wings and fuselage . The plane represents a new generation of efficient wide-body , long-range airliners , helping to make it among the world 's most watched aircraft . Airlines worldwide have committed to buy the plane , and hundreds of millions of dollars are riding on Dreamliner 's success . Boeing 's rival Airbus flew a similar airliner -- its highly anticipated A350 XWB -- for the first time on Friday at its facility in Toulouse , France . The entire global fleet of 50 Dreamliners was grounded in January after two battery overheating incidents triggered concerns among safety officials . Among the Dreamliner 's innovative new designs is a battery system that uses new , lighter lithium-ion batteries . Boeing and the Federal Aviation Administration collaborated on a new battery compartment which involved insulating the batteries and putting them in a ventilated armor-plated box to protect the rest of the plane .
United Flight 139 from Denver to Tokyo was diverted to Seattle on Tuesday . The unscheduled landing was `` due to an indication of a problem with an oil filter '' 787s returned to service this year after battery troubles grounded them for four months . A Boeing 777 is seen at Seattle-Tacoma International Airport in Seattle, Washington January 31, 2014.