All Nippon Airways (ANA) has returned to service two of the five Boeing 787s that have been grounded while an engine repair is carried out, although three more 787s will remain out of action for several days. However, network disruption has been minimal, as other aircraft are being used to fly the 787 routes.

The three 787s will “need another few weeks to fix” the engine issue that prompted the aircraft to be removed from service on July 21, an ANA spokesman says. So far, only two domestic flights have been canceled, both on July 21.

Boeing informed ANA that “there may be an issue with the gearbox” in the Rolls-Royce (R-R) Trent 1000 engines on its 787s, the airline spokesman says. While ANA stresses that “no related problems have arisen” in its 787 fleet, it found that the part identified by Boeing is fitted on five of its 11 787s. The other six aircraft are “not affected by this issue” and are continuing to operate normally, the airline says. R-R reportedly recommended that the gearbox part be replaced as a proactive measure.

Japan Airlines’ 787s have not been affected because they have General Electric GEnx engines, rather than Trent 1000s.