United Airlines and All Nippon Airways last week disclosed issues with the wiring on their Boeing 787's emergency transmitters, the same part of the plane that is getting close scrutiny after a parked Ethiopian Airlines jet caught fire at London's Heathrow earlier this month.
Boeing said its expanded request for inspections follows a recommendation by the U.K. Air Accidents Investigation Branch that airplane models with the Honeywell locator beacons be scrutinized.
"The purpose of these inspections is to gather data to support potential rulemaking by regulators," said Tinseth.
United Airlines said Friday it found a pinched wire during an inspection of one of its six 787s. Japan's All Nippon Airways found damage to wiring on two Boeing 787 locater beacons. It flies 20 of the jets.
The inspections of 787 Dreamliner jets were mandated by the Federal Aviation Administration for U.S. airlines after the fire in the tail of the Ethiopian Airlines 787.
U.K. investigators said the only thing in the tail section with enough power to fuel a fire like that was the emergency transmitter.
Dreamliner jets were grounded worldwide in January after separate problems with lithium-ion batteries that overheated or caught fire. Flights resumed four months later after a revamped battery system was installed in the airplanes.