Boeing Co. has traced the incorrectly assembled engine fire extinguishers on 787 Dreamliners to the manufacturing of bottles at a supplier’s facility while saying there were no risks to flight safety, the Wall Street Journal reported.

On Wednesday, Japanese airline ANA Holdings said it had found an electrical wiring problem in the fire extinguishers of the engines of three of its Boeing Dreamliner jets.

The problem was first discovered during pre-flight maintenance of a jet at Tokyo airport.

Boeing said in a written statement to the Wall Street Journal that the improper assembly, which has been confirmed to have been found on three ANA jets in Japan, “does not present a safety of flight issue because the bottles are not the only means of fire extinguishing for engines and there are multiple redundancies within the fire extinguishing system.”

A Boeing spokeswoman told the newspaper that activating the 787’s engine fire extinguishing system “does not disable or impact performance.”

“Regardless, improperly configured components are not acceptable and this issue is being addressed promptly. Boeing will follow standard disciplined procedures to understand how this discrepancy occurred and ensure it is not repeated,” the WSJ reported, citing Boeing statement.

Boeing could not immediately be reached for comment by Reuters outside of regular U.S. business hours.

(Reporting by Sakthi Prasad in Bangalore)

Photo Credit: The Boeing 787 Dreamliner sits on the tarmac at Boeing Field in Seattle, Washington, after its maiden flight, December 15, 2009. Robert Sorbo / Reuters