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Alaska Airlines probe focuses on 1997 inspection of stabilizer jackscrew
WASHINGTON (CNN) -- CNN has learned the National Transportation Safety Board is investigating a 1997 inspection of the same Alaska Airlines MD-83 that crashed last month, killing all 88 people on board.
Records indicated a key part on the aircraft was scheduled to be replaced and then later cleared to remain in the jet.
The report came as federally ordered inspections uncovered problems on at least 15 MD-80 series airliners in the United States, similar to the mechanical trouble suspected of contributing to the crash of Alaska Airlines Flight 261.
The 1997 inspection under scrutiny was a scheduled "heavy maintenance check" conducted September 29, 1997, at the airline's Oakland, California, facility.
The facility has been under federal investigation over allegations that some maintenance records may have been falsified.
During the check, NTSB Chairman Jim Hall said the stabilizer jackscrew and gimbal nut were checked for wear. A maintenance record said the initial measurement showed "the maximum allowable play end limit" and said the nut would be replaced during the check the next day.
But the NTSB said the records show the planned replacement was "re-evaluated" and the parts were checked again. The next check and four further checks found the parts "were within the specified tolerances." The results were then signed off by an Alaska Airlines maintenance inspector, and the parts were never replaced.
The NTSB said that inspection was the most recent maintenance activity involving a wear check on that part of the plane.
Hall said in a statement, "The significance of this information is continuing to be evaluated by the National Transportation Safety Board. No determination has been made as to whether this information has any bearing on the accident."
He said the airliner's jackscrew and nut are in a laboratory undergoing metal testing.
The horizontal stabilizers are winglike structures located on the tail of the aircraft. They control the plane's pitch, pointing the nose of the aircraft up or down.
Just before Flight 261 crashed, the plane radioed to Los Angeles International Airport that its horizontal stabilizers were stuck.
Jackscrew mechanisms associated with horizontal stabilizers were also linked to mechanical concerns discovered since Friday on at least 15 other MD-80s, according to Federal Aviation Administration chief Jane Garvey.
The discoveries were found during federally ordered inspections of all MD-80s as part of the investigation into the cause of the Alaska Airlines crash.
Asked about reports that 21 planes had been identified as having problems, Garvey told CNN's "Late Edition": "That probably will prove to be the case."
Problems with the mechanism are suspected of having contributed to the crash, which occurred off Port Hueneme, California.
On Friday, the FAA ordered inspections of all 1,100 MD-80s, MD-90s, DC-9s and Boeing 717s in the United States.
Garvey described the problems ranged from "very minor, which might just be normal wear and tear, to something that's more significant."
Garvey predicted the inspections would be completed by noon Monday.
An additional 900 MD-80 series planes fly outside the United States.
Though the FAA has urged that they be inspected, too, the U.S. agency cannot mandate their inspection. Garvey said the FAA expected to receive inspection status reports from international airlines by mid-week.
Garvey also responded to a U.S. News and World Report article that said Flight 261's horizontal stabilizer was made in China and that quoted a spokesman for the International Association of Machinists and Aerospace Workers as saying FAA oversight of non-U.S. parts manufacturers is inadequate.
Garvey said that the international organization that oversees aviation manufacturing "has some very high standards."
But she added, "I think that's going to be an issue that the NTSB will look at, and we may make some changes."
Boeing spokesman John Thom said Sunday that the manufacturer of the part used on Flight 261 had not yet been determined.
No matter where the parts are built, they meet the same stringent specifications, Thom said. "We insist on that. We'd be stupid if we didn't."
More problems found in third day of aircraft inspections
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