Date: 201907
Location: ZZZZ.Airport, FO
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Passenger Electronic Device
Detector: Person Flight Crew
When detected: Pre-flight
Result: General Maintenance Action; General Flight Cancelled / Delayed; General Release Refused / Aircraft Not Accepted
Contributing factors: Company Policy; Procedure
Primary problem: Company Policy

Narrative: Our [Maintenance Release] showed a cell phone was lost in the airframe of our aircraft and could not be recovered. When I saw this I realized that the airplane was flown in from [the U.S.] with a lithium ion battery lodged somewhere in the airframe. This is a serious on-board fire risk. Lithium ion batteries cannot be checked baggage due to the nature of the hazard they carry. We have fire suppression in the cabin including a fire bag for thermal runaway batteries. I called Dispatch; [Chief Pilot] and [Maintenance Control]. I put our situation in simple terms. We have a lost lithium battery somewhere in the airframe. Are you OK crossing the Pacific like this and is it legal to continue?Dispatch had no problem with this because if the battery was going to burn it would have by now. And it had just flown in this way. [Chief Pilot] researched our FOM and FM with no help. She called the Fleet Tech with very little input back. I was told after a long conversation that the decision is mine. [Maintenance Control] said they have 3 days to find the device and that they will dismantle the aircraft in order to retrieve the device. I asked if this so serious they take the airplane apart to find the phone is it safe to continue. The answer was that [the company] always returns equipment back to the passenger and this is how we do it. We dismantle the airplane! I asked what about the fire risk. [Another airline] just diverted due to an onboard battery fire. I did not want to be over the Pacific in the middle of the night when we caught on fire. [Maintenance Control] said the solution was to find the hot spot with your hands and shoot the extinguisher in near where the smoke and heat was coming from. That was the safety process for carrying a lost battery. All of this was pushing to bring the airplane home. After a very short conference with my crew I refused the aircraft. After 4 hours Maintenance found the phone in the airframe and we departed for home.A policy needs to go out on this. This will not be first or last time this event happens to a flight crew. Lost lithium batteries; dead or not; still hold voltage and amperage tied to a capacitor that stores energy. It is a very real fire risk and should never be accepted for flight in this condition. For one you do not know the condition of the battery that was lost. It might be have been crushed; damaged and shorted. Second; [Maintenance Control] solution of finding the hot spot with your hands is obviously not a viable solution. Third; Dispatch solution to flying the aircraft just because the battery had not burned up by now does not guarantee a dormant state. [Chief Pilot] needs to be supportive of a no-go with any lost lithium battery floating around in the airframe of an aircraft. There should be no other option.


Second narrative: [Report narrative contained no additional information.]


Synopsis: B777 flight crew reported refusing to fly an aircraft across the Pacific until a lost cell phone was found.