The Boeing 747 left Singapore on Feb. 25 at 11:35 p.m. (15:35 GMT) and landed at London's Heathrow Airport at 6:07 a.m. (06:07 GMT) the next day, arriving only 15 minutes behind schedule, BA spokesman Jay Marritt said.
Three hours into the 14-hour flight, an oil pressure indicator lit up, showing there was a problem with one of the engines, which the captain shut down as a precaution, Marritt said. It was the captain's decision to continue with Flight 18, which was carrying 356 passengers, he added.
''It's still very safe to fly a 747 on three engines,'' Marritt said. ''It is certified to do so.''
Six days earlier, the same aircraft lost power in one of its engines shortly after taking off from Los Angeles International Airport.
The pilot made an emergency landing in Manchester, England, about 260 kilometers (160 miles) short of London, because the Boeing 747 ran low on fuel after facing headwinds that were stronger than expected, the Federal Aviation Administration said.
The failed engine was later replaced in London, Marritt said. The aircraft then flew to Melbourne, Australia, before continuing to Singapore. It was the replaced engine that had to be shut down, the spokesman said.
''It was the No. 2 engine that failed but in totally different circumstances, it's one of those very strange coincidences,'' Marritt said.
The FAA and British aviation officials are investigating the Feb. 19 flight from L.A. to London to determine whether any regulations were violated.
''We are concerned,'' said Laura Brown, an FAA spokeswoman.
The decision not to return the L.A. to London Flight 268 after the engine lost power raised concerns about a new European Union law which requires European carriers to reimburse passengers for substantial delays.
U.S. officials said they have no evidence the airline's decision to continue on was influenced by the regulation.
''We would never compromise the safety of our passengers,'' said British Airways spokeswoman Diane Fung. ''The plane is certified to fly on three engines. It is perfectly safe to do so. The pilots are trained for such situations.
Flight 268 was carrying 351 passengers.
No one was immediately available for comment at Britain's Civil Aviation Authority.