Allegiant said in response to questions from Bloomberg that all its aircraft “were found to be in working order.”

By that time, mechanics had already come across two other jets with bolts in similar locations that weren’t properly locked in place, according to company repair logs obtained by Bloomberg. Later that month, they discovered another unsecured bolt on a third plane. While Allegiant says the fasteners weren’t on the same component that failed in Las Vegas, the U.S. Federal Aviation Administration says it is aware of the findings and has stepped up oversight of the airline.

“The FAA intensified its focus on the carrier’s flight operations and aircraft maintenance programs,” the agency said Oct. 15 in an e-mailed statement, without elaborating.