USA FAA は、ボーイング737型機体を緊急チェック!

F.A.A. to Order Airlines to Inspect 737s for Cracks By CHRISTINE HAUSER
Published: April 4, 2011 THE NewYorkTimes

A member of the N.T.S.B. investigating the emergency landing of Southwest Airlines Flight 812 cut away a portion of the plane's fuselage on Sunday, in Yuma, Ariz.

Hole in Southwest Jet Attributed to Cracks (April 4, 2011)
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Federal aviation authorities said on Monday that they would order airlines to inspect some early Boeing 737 models after Southwest Airlines found subsurface cracks in three aircraft during checks that were conducted after a five-foot hole ripped through the roof of a 737-300 jetliner on Friday.

The Federal Aviation Administration said that it would issue an emergency directive on Tuesday requiring inspections for fatigue damage. The action would initially apply to about 175 aircraft worldwide, 80 of which are registered in the United States, and mostly operated by Southwest Airlines.

“Safety is our No. 1 priority,” the Transportation secretary, Ray LaHood, said in a statement. “Last Friday’s incident was very serious and could result in additional action depending on the outcome of the investigation.”

The statement came shortly after Boeing said it was preparing a service bulletin that would recommend “lap-joint” inspections on certain 737-300’s as well as the 737-400 and 737-500 models.

Friday’s incident unfolded at nearly 35,000 feet with the sound of an explosion during a flight involving a 15-year-old Boeing 737-300 carrying 118 passengers from Phoenix to Sacramento. Some passengers reported feeling dizzy during the swift loss of cabin pressure. Oxygen masks were released and at least two people passed out as the pilot guided the plane to an emergency landing at Yuma Marine Corps Air Station in Arizona. No one was seriously injured.

The F.A.A. directive would require initial inspections using electromagnetic, or eddy-current, technology in specific areas of the aircraft fuselage on Boeing 737 aircraft in the -300, -400 and -500 series that have accumulated more than 30,000 flight cycles — one takeoff and one landing. It would then require repetitive inspections at regular intervals.

The Southwest aircraft involved in Friday’s incident had 39,000 cycles, and nearly 46,000 hours of flight.

On Monday, Southwest said its inspections had found three Boeing 737 jetliners with subsurface cracks.

“The cracks were found during the inspection process which uses a test designed to detect any invisible, subsurface fatigue in the skin,” Southwest said. “Those aircraft will remain out of service until appropriate repairs can be completed.”

The airline also canceled 70 flights from its schedule of 3,400 departures on Monday. About 300 flights were canceled on both Saturday and Sunday.

Southwest also said 57 of the 79 aircraft being inspected since Friday had been returned to service. In its statement on Monday, the airline said it expected to complete the inspections on Tuesday.

The airline said it was working to minimize the impact on customers.

Late on Sunday, another Southwest flight carrying 142 people was diverted to Los Angeles International Airport because of a burning electrical smell in the passenger cabin, but the airline said it was unrelated to the issue affecting the flight on Friday.

The 737-300 model plane had been flying from Oakland, Calif., to San Diego, according to Christi McNeill, a Southwest spokeswoman. No one was injured, and the passengers swapped aircraft and went on to their destination, she said.

The problem “was a gasper fan,” Ms. McNeill, referring to the system related to the vents above the seats. “If it gets overheated it can release a foul odor into the cabin.”

The National Transportation Safety Board said Sunday that the hole on the Friday flight was caused by fatigue cracks in the aluminum underskin of the lap joints in the plane. According to Federal Aviation Administration records, the airline identified and fixed 21 cracks in the fuselage of the plane involved in the incident on Friday 11 months ago during a scheduled inspection that lasted more than a week. Outside airline maintenance specialists say such fatigue cracks are not uncommon in older jets.

Southwest has a history of maintenance problems. In 2008, the F.A.A. proposed a $10.2 million penalty, later reduced to $7.5 million, for Southwest’s failure to do mandatory inspections for fuselage fatigue cracking on some of its Boeing 737s.

The airline’s own in-depth inspection of the plane in March 2010 revealed 10 cracks in parts of the frame and 11 cracks in the “stringer clips,” which help secure the aircraft skin, according to Service Difficulty Reports listed on the F.A.A. Web site.

They were all repaired, the reports said. At that time, the plane had 45,944 flight hours.

An F.A.A. spokesman said on Monday that no Airworthiness Directives had been issued before Friday’s incident that applied to that specific part of the fuselage. “As any carrier, Southwest submits a maintenance program to the F.A.A.,” the spokesman said. “If we had any cause for concerns, we would have certainly let them know."






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