Japan Airlines said Thursday a probe into a flight from Tokyo to New York that was forced to turn back after one of its engines caught fire showed it had sustained damage to many of its turbine blades.
Japanese officials have begun an investigation into Tuesday's "serious incident" at Tokyo's Haneda Airport where the jet carrying 233 passengers and 18 crew was forced into an emergency landing.
TV footage and photos showed flames shooting out of one of the engines shortly after take-off and a bird strike was initially suspected as the cause.
But a JAL spokesman told AFP on Thursday that many of the 220 turbine blades inside the left engine were "either broken or bent".
"There was also a scratch on the primary wing," he added.
Public broadcaster NHK said more than 200 blades were damaged, although the JAL spokesman said it was not immediately clear whether the damage occurred as a result of the fire or whether they were damaged before take-off.
Officials from the Japanese transport ministry are scouring the plane for clues as to what caused the incident.
The experts will examine the engine damage, conduct interviews with crew members and collect weather information from the day of the departure, according to a spokeswoman.
The plane returned to land safely an hour later and no injuries were reported.