American Airlines (Nasdaq: AAL) is on watch Friday following news that it's being sued by a major mechanics union over alleged misconduct of federal maintenance regulations.

The WSJ said that leaders of the Transport Workers Union Local 591 filed the suit against American in the U.S. District Court for the Northern District of Illinois on Thursday.

The union claims that the airline pressured members to breach members on maintenance, which includes items like cracks in wings and inspections for lightning strikes.

News comes during a critical integration year for American. The FAA is said to be investigating the allegations and American noted that it continually works with the FAA over such matters to ensure compliance.

Shares of American are down 0.2 percent in afternoon trading.