American Airlines Inc. canceled about 570 of today's flights as it continues its weeklong struggle with aircraft safety inspections.
Yesterday, the world's largest carrier scrubbed more than 930 flights nationwide - including 16 that were to depart from Logan International Airport.
That followed 1,094 cancellations on Wednesday and 460 on Tuesday as the carrier grounded all 300 of its Boeing MD-80s to inspect a cord lashed around a bundle of wires in the wheel shaft. The inspections have disrupted the travel plans of more than 171,000 American Airlines passengers this week.
MD-80s are 45 percent of the airline's 655-aircraft fleet.
The Federal Aviation Administration requires that the lashes be spaced no more than 1 inch apart and face in the same direction, among other things. If installed incorrectly, the cord could chafe the wires and cause the plane to lose auxiliary hydraulic power for the landing gear or spark a fire near the fuel tanks.
The FAA said it will be checking airlines' compliance with its requirements through June 30, and as a result, travelers can expect more disruptions.
American's chief executive, Gerard Arpey, told reporters the airline has not found chafed wires in the 100 planes that it had completed inspections on this week. The carrier put those planes back into service yesterday morning.
The airline predicts it will have about 170 MD-80s in service this morning, 210 by tonight, and all 300 by to morrow night.
Arpey refrained from giving a date when things would return to normal.
"Obviously, it's going to take us several more days to get up to speed," he said. "I can't anticipate any more hiccups we might encounter."
Even when all of the 129-seat or 131-seat MD-80s, which are the oldest type of aircraft in American's six-model fleet, are ready to take off again, some passengers may find themselves holding tickets to nowhere.
"The more cancellations you have, the more crews are out of sequence, and the harder it is to restart it," said Thomas J. Kinton Jr., chief executive of the Massachusetts Port Authority, which runs Logan.
Because a single plane and crew may be scheduled to hopscotch through several cities and countries before returning to the originating airport days later, it can take several days to untangle out-of-sync operations, he said.
Yesterday's 16 canceled departures at Logan prevented about 1,600 passengers from flying to Chicago, Dallas-Fort Worth, or St. Louis. Roughly the same number of American flights and passengers from those cities did not arrive at Logan.
Logan has not been affected as much as American's hubs, where cancellations have left scores of travelers stranded in terminals or sent them to nearby hotels the airline is paying for.
This is the second round of mass cancellations by American. Two weeks ago, the carrier canceled flights to inspect the same cord. This week, the airline grounded planes for a more comprehensive inspection.
Delta Air Lines Inc. and others also scratched flights in the past month to verify the condition of their aircraft as the FAA stepped up safety compliance. The FAA came under scrutiny in March for failing to closely monitor Southwest Airlines, which the agency subsequently fined for knowingly flying planes that missed inspections and contained cracks.
While American is offering full refunds or rebooking passengers on its own or its competitors' later flights, the situation still stinks for travelers.
"I'm quite upset by it," said Drew C. Bililies, president of Alternative Leisure Co., a Bedford tour group catering to disabled adults. Thirteen of his customers paid $1,499 for an all-inclusive, four-day Memphis vacation. But American scratched their 6 a.m. flight to St. Louis out of Logan. They were lucky to snag seats on a 3 p.m. American Eagle flight, but that required a three-hour layover at LaGuardia Airport in New York.
"These are special-needs people who are traveling on a flight I booked three to four months ago," said Bililies, whom the airline called at 9 p.m. the night before to announce the cancellation. He spent all evening and the next morning scrambling to reschedule the rental vans and other accommodations.
Bililies said he deserves compensation. "We're missing a day of fun," he said.
Nicole C. Wong can be reached at firstname.lastname@example.org. Paul Makishima of the Globe staff contributed to this report.