"These inspections are to ensure precise and complete compliance with the FAA's directive related to wiring in the aircraft's wheel wells," said a statement posted to travelers on American's Web site.
Officials said that passenger safety was never compromised, according to The Associated Press. The airline operates 2,300 flights daily and the cancellations have left thousands of customers stranded.
"There are about 30 MD-80s in service as of 7 a.m., and we should roll more back into service this morning and this afternoon," said American spokesman Tim Wagner, according to the Dallas Morning News. "The situation is fluid, though, and that is why we have gone ahead and cancelled the 850. We do not know at this point if that number will climb, but it might."
Additional cancellations are likely on Thursday, a company press release said.
American cancelled half of its flights to and from the Dallas/Fort Worth International Airport, the airline's largest hub, forcing passengers to make accommodations on other carriers and even traveling to nearby cities in order to book a flight.
In March, American cancelled 500 flights for the same wiring concern on its MD-80 fleet, but an audit by the Federal Aviation Administration on Monday found that the changes did not meet FAA standards, according to Wagner.
Delta Air Lines also cancelled flights in March to complete wiring inspections.
The increased scrutiny of U.S. carriers began after lapses in the FAA's oversight of airline safety checks came to light. Several large carriers have been forced to ground planes and cancel flights in order to reinspect equipment.
The FAA lapses involved allegations that the agency had allowed Southwest Airlines to fly airplanes that had missed safety inspections due to a "cozy" relationship between FAA officials and the airline.
John Goglia, a former member of the National Transportation Safety Board, told the NewsHour after congressional hearings on the Southwest airlines inspections that more investigations would be needed to fully assess the scope of the danger.
"Well, they certainly flew airplanes that went over the regulations. Whether or not they were truly unsafe is yet to be determined," Goglia said.