NTSB wants Rolls-Royce to redesign engines used on Boeing 777s

A U.S. safety board issued an "urgent" recommendation calling for the redesign of a Rolls-Royce Group engine component to prevent a loss of thrust in Boeing 777s.

The recommendation by the National Transportation Safety Board (NTSB) follows two reports of engines losing thrust aboard 777s, including a British Airways jet that crash landed January 2008 in London. Both cases involved a buildup of ice restricting the flow of fuel to the engine, the NTSB said.

"We believe that there is a high probability of something similar happening again," NTSB Acting Chairman Mark Rosenker said in a statement. He added that he was "encouraged" that Rolls-Royce was already working on a redesign.

The recommendation asks U.S. safety regulators to require that Rolls-Royce redesign the fuel-oil heat exchanger for RB211 Trent 800 series engines, which Boeing said are used on more than 180 of its 777s worldwide. The component "can be overwhelmed by ice" formed inside the 777 fuel-feed system from normal amounts of water in jet fuel, the NTSB said in its letter to regulators.

The NTSB also asked the Federal Aviation Administration to require that airlines be forced to install the redesigned fuel-oil heat exchangers in Boeing 777-200 engines within six months of the new part's certification.

"We will take a look at it, and we'll get back to the board as we always do," FAA spokeswoman Laura Brown said of the recommendation. The NTSB is an independent government board that investigates accidents and makes recommendations, yet cannot compel regulators to take action.

Ginny Person, a Rolls-Royce spokeswoman in the U.S., didn't immediately return a telephone call or e-mail for comment.

Boeing spokesman Jim Proulx said the company is "studying the recommendation and we will work with our customers and regulators as required."

The British Airways 777 crash-landed on Jan. 17 of last year after the Rolls-Royce engines failed to provide sufficient thrust on approach to London Heathrow Airport. None of the 152 passengers and crew was killed.

The plane flew from Beijing through temperatures of minus 99 Fahrenheit, possibly thickening the fuel and reducing its flow, the U.K.'s Air Accidents Investigation Branch said in September.

U.K. investigators recommended that 777 pilots be told to rev their engines before landing to clear ice from fuel lines, after frozen kerosene was blamed for the crash landing.

In the other incident, a Delta Air Lines plane was cruising at 39,000 feet over Montana on Nov. 26 when one engine lost a "significant" amount of thrust, the NTSB said in December.

The engine recovered after pilots descended to 31,000 feet, and the 777 landed safely in Atlanta. The Delta flight was traveling to Atlanta from Shanghai with 15 crew and 232 passengers, according to the NTSB.

After the Delta incident, Boeing revised its operating procedures to instruct crews to clear ice accumulation by briefly increasing thrust two hours before descent, rather than the three hours it had advised earlier, to reduce the time available for ice buildup, the NTSB said in its letter.

The board said that neither the early nor revised procedure was sufficient, since the Delta power loss happened more than three hours before descent.

The procedure "is not an acceptable substitute for immediate development of an engineering solution," according to the NTSB letter.