http://online.wsj.com/public/article_print/SB120277026942260315.html
United, American Plan Safety Push
After Icing Linked to British Crash
By ANDY PASZTOR
February 12, 2008; Page D6
Prompted by suspected ice accumulation in the fuel system of a
British Airways PLC jumbo jet that crash landed near London last month, two major U.S. carriers are stepping up safety initiatives to prevent such problems, according to people familiar with the matter.
The moves come amid growing indications that a buildup of ice crystals or slush simultaneously restricted fuel flow and reduced the thrust of both engines of the Boeing 777 jet moments before the Jan. 17 accident at Heathrow International Airport, these officials said.
UAL Corp.'s United Airlines, and
AMR Corp.'s American Airlines are taking precautionary steps to ensure fuel quality and re-evaluate fuel characteristics before investigators release preliminary findings. While it is common for airlines to ramp up safety efforts in the wake of a high-profile crash, they typically wait until the release of such findings or early safety recommendations by regulators or manufacturers.
United is reassessing certain quality-control systems it uses for accepting and testing fuel at airports, according to these people, and is reviewing procedures its mechanics use to drain water from jetliner fuel tanks. American has launched an effort to determine if a different type of jet fuel could better withstand temperature extremes on the longest and coldest polar routes, other officials said.
The moves come as U.S. and British investigators are focusing on whether ice crystals may have clogged the plane's dual oil-cooler systems, according to people familiar with the details. The radiator-like devices use fuel flow from each of the wing tanks to cool engine oil, and fuel then flows from there to the nearby engine during flight.
Investigators also want to determine how mechanics who worked on the aircraft before a pair of earlier flights may have reacted to warnings of potential ice buildup in the fuel. An internal Federal Aviation Administration memo last month said "a maintenance message indicating excessive water in the center tank was set during taxi on the two previous flight legs, although it cleared itself both times."
Water can be drained from Boeing 777 fuel tanks only on the ground, so part of the puzzle is what mechanics did to ensure the fuel system wasn't contaminated. United's routine procedures call for removing excess water after every several hundred flight hours.
United, American and
Rolls-Royce Group PLC, which made the engines on the plane that crashed, have declined to comment on the investigation.
Boeing Co., which said its 777 aircraft flew for 12 years and about 3.6 million hours world-wide without a major accident, said "it would be inappropriate to comment at this stage." The crash didn't result in fatalities.
The analysis and safety-oversight efforts by the airlines haven't uncovered any significant new icing-related hazards or resulted in operational changes. British regulators are expected to issue an update on the probe within a few days, though they don't appear ready to release new safety mandates or recommendations. The latest moves highlight how closely large segments of the global aviation industry are following the investigation, believed to be the first time ice contamination in fuel brought down a large, state-of-the-art jetliner with no apparent mechanical or computer malfunctions.
The FAA recently asked U.S. carriers that fly Boeing 777 aircraft to comb through their historical safety data to identify instances when engines were slow to rev up in response to pilot commands, or may have reduced thrust on their own, according to one person familiar with the investigation.