Boeing's 787 Dreamliner has hit its latest problem — Japanese airline ANA says that three of its 20-strong fleet have shown an electrical wiring issue with their engine fire extinguishers. An airline spokesperson told Reuters that the discovery was first made during pre-flight maintenance in Tokyo.

It's not yet known whether the fault could stop the extinguishers working in the event of a fire, but Japan Airlines, a competitor of ANA, said it forced a 787 bound for Helsinki to turn back for examination. The airline says it is currently performing similar checks on its fleet of ten Dreamliners.

The sophisticated 787 has suffered a litany of setbacks since its maiden US flight last year, with airlines worldwide grounding their fleet until Boeing found a solution for a battery issue. The aircraft went back into active service earlier this year, but has continued to run into problems; last month an Ethiopian Airlines 787 caught fire while parked at London's Heathrow airport, causing both runways to be closed.