The National Transportation Safety Board issued an "urgent" safety recommendation Wednesday night, telling the maker of a popular jet engine to change the way a part of the engine is designed.
In its statement, the NTSB said a redesign of the problematic engine part is the "only acceptable" long-term solution.
The safety board's decision to issue the warning comes after two incidents in the sky. In both cases, Rolls-Royce Trent engines on Boeing 777s experienced a loss of thrust in flight, apparently because of ice build-up on a fuel exchanger in the engine.
One of the planes, a British Airways 777, crashed short of a runway at London Heathrow Airport in January 2008. Nine passengers on board were injured, one seriously.
In the second incident, a Delta Airlines 777 experienced an "engine rollback" in flight in November 2008 over Montana. The crew was able to recover and land the plane safety.
Investigators say they believe ice buildup is occurring because of water that is normally found in all jet fuel, and not from icy weather.
Fort Worth-based American Airlines uses the same engine on its fleet of 777s, but American has not reported any problems in flight.
A spokesman for the airline, Tim Smith, said American's flight crews have been complying with an FAA directive issued earlier to address the issue. Smith said those procedures have "worked well."
The FAA directive instructs flight crews on procedures to operate the engines in a way that reduces the chance of ice buildup.
The board said Rolls-Royce is working on a redesign and hopes to have the part ready for installation in 12 months.