SEATTLE (AP) — Saying earlier inspections may have produced incorrect readings, Alaska Airlines is grounding as many as 18 Boeing MD-80 airliners for another look at a part implicated in January's crash that killed 88 people.
The airline told the Federal Aviation Administration that a tool used to check jackscrews — key steering components in jets' tails — may have resulted in erroneous readings. It said the remaining 16 MD-80s in its fleet did not require the new inspections, which by Friday had resulted in 90 flight cancellations.
The airline's president conceded late Thursday that the tool used to check the doomed plane was made by Alaska Airlines and not the jet's manufacturer, but he insisted the aircraft were safe and said airlines commonly make and use their own tools.
There are no indications of problems, the FAA said in a statement Thursday night. But the agency is alerting other airlines using MD-80s — as well as DC-9 jets, which are also affected — to check their planes.
Out of about 2,000 MD-80 and DC-9 jetliners worldwide, more than 1,100 are flown by U.S. carriers.
Alaska Airlines Flight 261 plunged into the ocean off Southern California on a flight from Mexico to San Francisco on Jan. 31. Everyone aboard the MD-83 — an MD-80 variant — was killed.
A criminal investigation into the crash focused on a mechanic's decision not to replace a jackscrew assembly. The assembly consists of a nut that rides up and down a screw as it turns to raise and lower the stabilizer, a wing-like part of the tail used to tilt the nose of the plane in flight.
Flight 261's jackscrew had been tested repeatedly and found to be nearly worn out, but was put back into service after a second crew retested it a few days later. Two Alaska Airlines mechanics insisted in an interview with The Seattle Times that they were not at fault.
The tool in question measures the amount of space between the thread on the jackscrew and the nut that holds it in place.
The airline's tests, conducted during the National Transportation Safety Board investigation of the fatal crash, indicated that "endplay" measurement could vary. According to the MD-80 maintenance manual, airlines can measure jackscrew "endplay" using a tool made by the aircraft manufacturer or an equivalent substitute.
Alaska Airlines owns tools made by the manufacturer but also uses several that were made in its own machine shop. In side-by-side testing by the airline, the different tools produced the same measurements, the airline said. However, the airline found measurements could vary if its own tool was improperly positioned.
The airline's own tool was used to measure the jackscrew on Flight 261, Alaska Airlines President Bill Ayer said.
"It is up to the U.S. attorney's office and the NTSB to determine if this tool is a problem in their investigation," he said at a news conference.
Ayer said it was a common practice among airlines to make their own maintenance tools. He also declared the MD-80s to be safe: "There's no more inspected airplane in the world than the MD-80, especially the Alaska MD-80s."
In June, the FAA announced that Alaska Airlines had made sufficient improvements to continue doing maintenance on its planes. Previously, the agency had threatened to strip the airline of the right to do maintenance — a step that could have eventually grounded all its planes — unless its programs were improved.
Alaska, which has 500 departures daily, has a fleet of 92 planes, 34 of which are MD-80s. Once the airline verified that the manufacturer's tool was used to measure the jackscrews on 16 of its MD-80s, it decided to reinspect the remaining 18.
The new inspections resulted in 18 flight cancellations Thursday night and 72 more on Friday, airline spokesman Greg Witter said. The airline hoped to complete the inspections by late Friday but service disruptions were expected to last at least through Saturday.