The agency investigating a fire aboard a parked Boeing Dreamliner at Heathrow airport in London has recommended that Honeywell distress beacons on all 787 planes be deactivated pending further checks.
However, the Air Accidents Investigation Branch said it is not clear whether the fire originated in the transmitter batteries or was caused by an "external mechanism such as an electrical short".
Nobody was hurt in the fire last Friday on an Ethiopian Airlines plane, which was empty at the time.
Boeing withdrew from service its entire fleet of Dreamliners earlier this year due to concerns that lithium ion batteries on board could cause fires.
A total of 68 Dreamliners have so far been delivered, and the AAIB recommends to US aviation agencies that emergency locator transmitter systems in each of them be made inert.
