TOKYO (Reuters) - Japanese airline ANA Holdings said it had found an electrical wiring problem in the fire extinguishers of the engines of three of its Boeing Co Dreamliner jets.
The problem was first discovered during pre-flight maintenance of a jet at Tokyo airport, an ANA spokeswoman said.
The airline, which operates the world's biggest fleet of the Boeing 787 jets, is investigating whether the faulty wiring would have caused the extinguisher to malfunction in case on an engine fire.
ANA operates 20 Dreamliners.
After ANA reported the fault, rival Japan Airlines turned back a 787 jet en route to Helsinki to check the fire extinguisher wiring. JAL is now conducting checks on all ten of its 787s, a spokesman for the airline said.
The 787, Boeing's newest and most advanced aircraft, has suffered a spate of problems since its first flight in December 2009.
In the latest incident, fire broke out on an Ethiopian Airlines 787 at London's Heathrow airport on July 12, triggering inspections of beacons used to locate aircraft in the event of a crash.
Reporting by Tim Kelly; Editing by Miral Fahmy