DALLAS — U.S. regulators will tell airlines to quickly make changes aimed at preventing ice from building up in fuel lines of Boeing 777s, which British investigators said Thursday probably caused one of the jets to make a jarring emergency landing last January in London.
The Federal Aviation Administration’s formal directive by week’s end will require changes in the way ground crews prepare planes and pilots fly them in extreme cold weather, FAA spokeswoman Alison Duquette said Thursday.
Currently, 777 pilots are required to rev their engines when the fuel temperature falls to 14 degrees Fahrenheit. That would conceivably dislodge any ice that might be in the fuel line.
The FAA directive will apply to more than 50 U.S.-registered Boeing 777s with Rolls-Royce engines, mostly operated by American Airlines and Delta Air Lines Inc.
FAA spokesman Les Dorr said the directive is viewed as an interim measure, and Rolls-Royce will be expected to make design changes to its engines.
The U.K. Air Accidents Investigation Branch recommended that the FAA and European regulators immediately consider whether the same problem could occur in planes with different engines — a move that could affect many more carriers.
Duquette said, however, that the FAA’s initial review “has not revealed the same vulnerability to ice buildup in the fuel lines” of Boeing 777s with different engines.
The report by the British investigators also recommended that regulators review certification requirements to make sure fuel systems can cope with possible ice buildup.
The investigators said water — normally present in aircraft fuel — probably froze in the fuel lines and caused a British Airways jet to lose power and make an emergency landing just inside the Heathrow Airport boundary Jan. 17. More than a dozen people suffered injuries, including one listed as serious.
The flight from Beijing had been uneventful until its final approach. Just 720 feet above the ground, the jet began losing power in the right engine and, seven seconds later, in the left one, investigators said in a report issued Thursday. They said those events were consistent with a drop in fuel flow.
“Although the exact mechanism in which the ice has caused the restriction is still unknown in detail, it has been proven that ice could cause a restriction in the fuel feed system,” the report said. “The risk of recurrence needs to be addressed in the short term whilst the investigation continues.”
