Hong Kong ( CNN ) -- The woes of Boeing 's new 787 mount as U.S. regulators ordered airlines to stop flying their Boeing 787s . The U.S. move comes after two fleets of Boeing 787s have been grounded in Japan after alarms and a burning smell in the cabin forced a Dreamliner to make an emergency landing Wednesday . The incident is the most serious in a spate of problems that have bedeviled the new aircraft , and comes after the U.S. Federal Aviation Administration , which is responsible for air safety , launched a comprehensive examination on Friday of the Dreamliner 's design as well as its manufacture and assembly . `` The Boeing 787 incidents have taken on a new seriousness with the grounding '' by All Nippon Airways ( ANA ) and Japan Airlines ( JAL ) , said Richard Quest , CNN 's aviation correspondent . `` The potential of fire on board an aircraft is among the most serious issues in aviation , '' he said . `` The plane is still safe to fly . However , Boeing must ensure the reliability of the aircraft for the airlines and the confidence of the traveling public to fly on the planes . `` That is the fundamental problem that Boeing is now facing , '' Quest said . U.S. grounds Dreamliners over fire risk . What happened ? As CNNMoney reports , a Boeing 787 operated by All Nippon Airways was forced to make an emergency landing Wednesday in Japan . The domestic aircraft was traveling to Tokyo when irregular battery activity and smoke in the forward electrical compartment were detected . The aircraft then made an emergency landing at Takamatsu airport after a burning smell was detected in the plane 's cabin . Following the incident , both All Nippon and Japan Airlines said they were immediately grounding their Dreamliner fleets -- which effectively grounds about half of the Dreamliners now in operation worldwide . The Japanese airlines were among the first to take delivery of the Boeing 787 . ANA has 17 aircraft , while JAL has seven Dreamliners . Worldwide , Boeing has delivered 50 Dreamliners -- but hundreds more are on order . More than 150 Dreamliner flights occur daily , according to Boeing . Japanese airlines suspend Dreamliner flights after emergency landing . What problems has the Dreamliner had ? In recent weeks , many . The most recent Dreamliner setbacks occurred Friday . Oil was discovered leaking from a generator on an engine at a Japanese airport , and a crack appeared in a cockpit window of a plane en route from Tokyo to western Japan , a spokeswoman for All Nippon Airways said . On January 8 , a Japan Airlines flight bound for Tokyo aborted takeoff from Boston 's Logan International Airport after a pilot on another airplane spotted the 787 leaking fuel . On January 7 , a maintenance worker discovered the electrical fire aboard an empty plane being prepared at a gate at Logan for a return trip to Japan . Another Japanese flight was cancelled last week after sensors detected problems with the plane 's braking system . In December , a United Airlines 787 traveling from Houston to Newark , New Jersey , was diverted to New Orleans because of mechanical problems . A general inspection of all 787s in September turned up cracked engines on two planes . The woes come after the debut of the plane in 2011 -- nearly three years behind its production schedule . Related : More trouble for Boeing as Dreamliner forced to make emergency landing . Do Dreamliners fly in the U.S. ? United Airlines -- which has six 787s -- debuted the nation 's first domestic Dreamliner routes last November . `` We continue to have complete confidence in the 787 and the ability of Boeing , '' United said Friday in a statement . The airline described the problems as `` early operational issues . '' United 's Dreamliner fleet travels primarily on routes connecting Houston and Chicago and between Newark and Los Angeles . Last week , the airline kicked off its first international 787 service between Los Angeles and Tokyo . Other U.S. carriers are in line to buy Dreamliners , including Delta . American Airlines has announced an order , but it 's not yet `` firm . '' What does the troubles mean for Boeing ? The company 's stock has taken a hit as the troubles mount . Several hundred are under order , making its success crucial for Boeing , which had not designed a new commercial jetliner in years before unveiling the Dreamliner . `` The 787 , being a new airplane , does have teething problems , '' John Goglia , a former member of the National Transportation Safety Board , told CNN last week . It 's common for new planes to have `` these kinds of problems , '' he added . Airlines have been excited by the Boeing 787 as the first mid-size , long-range airplane , which would allow airlines to open up routes where they do n't have enough demand from passengers to justify a larger plane like a Boeing 747 or an Airbus A380 . Related : How the 787 will change the way we fly . Boeing has more than 800 unfilled orders from airlines around the globe that will take years to fill . In addition to the Dreamliner assembly line at its Seattle-area factory , it built a new 1,000-worker factory in South Carolina to handle the demand . It hopes to double production of the plane this year to about 10 a month . CNNMoney 's Charles Riley and CNN 's Yoko Wakatsuki and CNN Wires staff contributed to this report .
NEW : U.S. regulators have ordered airlines to stop using their Boeing 787s . Two jets of Boeing 787s have been grounded in Japan after one jet made an emergency landing . The woes come after the delivery of the plane in 2011 , nearly three years behind its production schedule . About 50 aircraft have been delivered ; Boeing has more than 800 unfilled orders from airlines .