“Cracks appear a few times every year in other planes. We don’t see this as a sign of a fundamental problem” with Boeing aircraft, a spokesman for the airline said.

On the later flight, the ANA spokeswoman said she could not specify how much oil leaked from the engine.

The latest incidents came just hours before ANA was due to launch its maiden service between Tokyo and San Jose, California with the 787. That flight was due to leave Tokyo at 0830 GMT, returning to Japan after an around 90-minute turnaround in the United States.

ANA and JAL together fly 24 of the 49 Dreamliners delivered to end-December.

In India - where state-owned Air India has taken delivery of six 787 jets and has more on order - a senior official at the aviation regulator said there was concern at the recent spate of 787 glitches. The Directorate General of Civil Aviation has not ordered any 787 checks for now, but is waiting for a safety report from the U.S. National Transportation Safety Board, the official said.

Air India spokesman K. Swaminathan told Reuters that the airline’s debut 787 flight from India to Paris on Thursday went without a hitch.