US aviation officials are examining why American Airlines asked mechanics to start skipping some safety checks to detect damage to planes from suspected lightning strikes, the Wall Street Journal said on Friday, citing internal company and agency documents.

The regional Federal Aviation Administration office overseeing the airline is asking questions about the issue, in the first step of a possible formal investigation, the report said, citing people familiar with the details.

If the FAA concludes that American exceeded its authority in making the changes, it could face formal enforcement proceedings resulting in a civil fine and another change in procedures, the Journal added.