ANA has started removing some Boeing 787 Dreamliners from service for engine replacement and repair after finding faults on some of its Rolls-Royce engines.

ANA said the problem is fatigue cracks in the blades of the engine’s intermediate pressure turbine.

“We have been working with Rolls-Royce, the designer and manufacturer of the engines in question, to implement permanent technical solutions to this issue,” ANA said in a statement.

“We have decided to replace the engines on aircraft used for domestic operations earlier than what was designated by Rolls-Royce. This has led to a temporary reduction in available aircraft, which in turn has led to some flight cancellations.”

ANA has received 50 787s out of total orders for 80 and is the largest customer of the Dreamliner.