US aviation regulators told airlines on Thursday they should remove or inspect emergency locator beacons on Boeing 787s after a recent fire on one of the jetliners.
The Federal Aviation Administration issued a new airworthiness directive, or AD, that stepped up its precautions over the beacons on the cutting-edge Boeing plane.
"This AD requires either removal or inspection of the Honeywell fixed emergency locator transmitter (ELT), and corrective action if necessary," the FAA told airlines.
On Saturday, the FAA issued an AD that only asked airlines to inspect the beacons.
The FAA said the call to either remove or inspect the beacons "was prompted by a report of a fire involving a Honeywell fixed ELT."
"We are issuing this AD to prevent a fire in the aft crown of the airplane, or to detect and correct discrepancies within the ELT that could cause such a fire."
The fire occurred on July 12 on an empty 787 owned by Ethiopian Airlines and parked at London's Heathrow airport. No one was injured.
British authorities recommended a week ago that the distress beacons onboard all Boeing Dreamliners be disabled, after identifying the devices as the likely cause of the fire.
The beacon issue adds to safety concerns about Boeing's jetliner, a long-range plane built largely of lightweight composite materials. The 787 entered service in October 2011.
Regulators grounded all 787 Dreamliners in service in mid-January after two safety incidents involving the plane's lightweight lithium-ion batteries.
Overheating on the batteries caused a fire on an empty, parked 787 and forced an emergency landing on another.
More than three months later, Boeing 787s were cleared to fly again after regulators approved Boeing's proposed battery fix.