The FAA said it has increased oversight of United Airlines after a string of incidents.
More FAA officials will be dispatched to United facilities to review work processes and manuals and to examine facilities.
"As part of this effort, the FAA will pause a variety of certification activities for a period of time," United vice president of corporate safety Sasha Johnson said in a staff memo.
In a statement, the FAA said, "Certification activities in process may be allowed to continue, but future projects may be delayed based on findings from oversight."
Neither side has specified the certification activities that will or might be curtailed.
A string of United safety-related incidents this month are under FAA investigation. None have caused injuries or fatalities. Most spectacularly, on March 7 a tire fell off a United Airlines Boeing 777 while departing from San Francisco for Osaka, Japan. The tire landed in an employee parking lot at SFO, damaging several cars.
The incidents led United CEO Scott Kirby to send an email to customers last week in an effort to reassure them about the airline's safety culture.