Three Incidents Of In-Flight Malfunctions Reported

The Alitalia 777 seemed to stagger in mid-flight, not far off the coast of Ireland. Passengers on board the flight last July initially panacked, demanding to know what was going on. The crew, however, was busy figuring that out for themselves.

The twin-engine superjet made a U-turn and headed to Shannon, Ireland. There, maintenance crews found the 777's windshield heater had malfunction, causing the windscreen itself to crack.

"That window looked like something out of an automobile junkyard," said one passenger.

Boeing officials traced the problem to faulty wiring in a window heater. At least two other Boeing 777s have experienced the same problem in the past year, according to the wire service.

The 777 entered service in 1995. It can carry  up to 550 people and costs between $153 million and $231 million each, depending on the model. There are 138 registered in the United States, according to FAA records.

Their windscreens, made of three layers of glass, acrylic and epoxy, can get brittle in the cold, thin air at cruising altitude. So, they're kept reasonably warm by a heater that allows them to stay elastic. The wires on the three planes that suffered cracked windshields loosened and shorted out.

On the Alitalia flight, the short caused a small fire and the innermost layer of the window cracked, Boeing spokeswoman Liz Verdier said. The crew on the Alitalia flight put out the fire with an extinguisher in three seconds and then brought the plane down to 10,000 feet. That reduced the difference between the pressurized cockpit and the thin air outside, said Bill Waldock, aviation safety professor at Embry-Riddle Aeronautical University in Arizona. The danger at high altitudes is that the windshield could shatter and loose items or people could be sucked out, though that's never happened on a commercial flight.

Boeing has now sent a directive to airlines telling them how to tighten the wire connections on the windsheild heaters. Boeing also is working circuit breakers that will prevent sparking and the window from overheating, Verdier said.

FAA officials said Boeing is taking appropriate action. "Anytime there's a fire, there's a concern to us," FAA spokesman Paul Takemoto said. "But cracked windshields rarely affect the safety of the aircraft."

FMI: www.boeing.com