B777 first officer reported that a faulty oven in the aft galley resulted in smoke and possible fire...

Narrative:

At FL180 on climb out; the flight attendants called up to the cockpit to report smoke coming out of several ovens in the aft galley. I as relief pilot told the captain that I would go back and assess the situation. When I arrived in the aft galley there in fact were several smoking ovens with real smoke. We immediately de-powered the galley and removed all food from the ovens. I called to captain and told him that I was concerned that it was an issue different than spilled food because 6 of the 8 ovens were billowing smoke. There was no sign of spilled food or grease in any of the ovens. At that point the captain advised ATC and made a turn to return to ZZZ for landing. I maintained coordination with the flight attendants and had them de-power all the galleys in the airplane including pulling the circuit breakers. I returned to the cockpit and took over all communications with dispatch; the flight attendants; the passengers; and crash fire rescue on the ground in ZZZ. On final approach into ZZZ the flight attendants called and said the ovens were smoking again. This was 15 minutes after power had been removed. I instructed them to shoot the ovens with the halon extinguisher. They did and arrested the smoke. We landed without further incident. Taxied to the gate and replanned the passengers.

Original NASA ASRS Text

Title: B777 First Officer reported that a faulty oven in the aft galley resulted in smoke and possible fire and resulted in a return to land.

Narrative: At FL180 on climb out; the flight attendants called up to the cockpit to report smoke coming out of several ovens in the aft galley. I as relief pilot told the Captain that I would go back and assess the situation. When I arrived in the aft galley there in fact were several smoking ovens with real smoke. We immediately de-powered the galley and removed all food from the ovens. I called to Captain and told him that I was concerned that it was an issue different than spilled food because 6 of the 8 ovens were billowing smoke. There was no sign of spilled food or grease in any of the ovens. At that point the Captain advised ATC and made a turn to return to ZZZ for landing. I maintained coordination with the flight attendants and had them de-power all the galleys in the airplane including pulling the circuit breakers. I returned to the cockpit and took over all communications with Dispatch; the flight attendants; the passengers; and Crash Fire Rescue on the ground in ZZZ. On final approach into ZZZ the flight attendants called and said the ovens were smoking again. This was 15 minutes after power had been removed. I instructed them to shoot the ovens with the Halon extinguisher. They did and arrested the smoke. We landed without further incident. Taxied to the gate and replanned the passengers.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1694015
Time
Date	201910
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B777-200
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Galley Furnishing
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 166 Flight Crew Total 9821 Flight Crew Type 1238
Events
Anomaly	Aircraft Equipment Problem Critical Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor

B777 first officer reported that a faulty oven in the aft galley resulted in smoke and possible fire and resulted in a return to land.