WASHINGTON – The U.S. Department of Transportation will audit the FAA's oversight of maintenance at troubled Allegiant Air, which was the subject of a Tampa Bay Times investigation and more recent reporting from 60 Minutes.

"Our objectives now are to assess FAA's processes for investigating allegations of improper maintenance practices at two carriers, Allegiant Airlines and American Airlines," the DOT's inspector general's office wrote in a memo announcing the expanded audit.

(Sen. Bill Nelson, who called for such a probe, highlighted the memo on Wednesday.)

"Specifically, we will (1) examine FAA's independent reviews, complaints to the FAA hotline, and other sources to see whether inspectors conducting routine surveillance of Allegiant and American Airlines found similar discrepancies and (2) determine whether FAA ensures that Allegiant and American Airlines implement effective corrective actions to address the root causes of maintenance problems."

Said Nelson, the top Democrat on the Commerce Committee:

"The traveling public deserves to know the whole story when it comes to the FAA's oversight of airline maintenance. I expect the inspector general to leave no stone unturned."

Read more: The Tampa Bay Times investigation.