Second Mishap For 777

A new Boeing 777 that made an emergency landing was the second model to experience decompression because of an air-conditioning duct valve failure, company officials said Friday.

Four of the 19 test crew members were hospitalized with decompression sickness Thursday after an air duct clamp gave way and a check valve failed, allowing air to rush out of the cabin of the No. 2 model some 30 miles north of Seattle at an altitude of 43,100 feet. All had been treated and released by Friday.

Flight tests in the plane resumed Friday afternoon, about 25 hours after the incident.

The part that failed was returned to the supplier, an outside company Boeing officials refused to identify, for analysis and testing, said J. Kenneth Higgins, Boeing’s chief of flight testing.

Until the investigation is completed, all six test models of the 777 have a flight ceiling of 25,000 feet by mutual agreement between Boeing and the Federal Aviation Administration, Higgins said.

“This incident will have no impact on the overall 777 program, and first delivery to United Airlines remains on schedule for May 15,” Boeing said in an unsigned news release Friday.

The release revealed that the same gear failed under similar conditions Tuesday as the No. 3 model of the 777 was ascending, flying at about 22,500 feet near Kona, Hawaii. No one aboard suffered any ill effects.

In that case, the part failure resulted from the wear and tear of frequent opening and closing to inspect the equipment, and flight tests resumed as soon as the parts were replaced.