CLEARWATER, Florida — Allegiant Air’s aircraft are four times as likely to fail during flight as those operated by other U.S. airlines, an investigation by the Tampa Bay Times has found.

Presented with the Times’ findings during an interview at Allegiant’s Las Vegas headquarters, the carrier’s CEO, Maurice Gallagher Jr., said, “I can’t sit here and say that you’re wrong. We’re very much focused on running a better operation.”

In 2015, Allegiant jets were forced to make unexpected landings at least 77 times for serious mechanical failures, the Times’ first-of-its kind analysis of federal aviation records shows. One of those incidents involved Flight 2874 from Clearwater to Bangor, Maine, on July 1, 2015, when the left engine failed and the plane was forced to return to Clearwater, where the engine was replaced.

None prompted enforcement action from the Federal Aviation Administration.

To create such a comparison, Times reporters built a database of more than 65,000 records from the FAA.

Working through the data, they connected a year’s worth of flight records with documents showing mechanical problems at the 11 largest domestic carriers in the United States, including Allegiant.

The airline did not dispute the newspaper’s findings, which included:

— Forty-two of Allegiant’s 86 planes broke down in mid-flight at least once in 2015. Among them were 15 forced to land by failing engines, nine by overheating tail compartments and six by smoke or the smell of something burning. In addition to Flight 2874, at least one other incident involving a Florida to Bangor route was not counted because it was not marked by Allegiant in its “mechanical interruption summary reports.” Flight 736 en route to Bangor from the Sanford airport was diverted on Dec. 30, 2015, to T.F. Green Airport in Warwick, Rhode Island, where it landed safely after passengers said they smelled something “burning.” Allegiant later said there was no fire or smoke, but that the “abnormal smell” originated from a leak in an air duct in the MD-83 aircraft.

— After certain systems on Allegiant planes fail, the company repairs them and puts the planes back in service, only to see the same systems fail again. Eighteen times last year, key parts such as engines, sensors and electronics failed once in flight, got checked out, and then failed again, causing another unexpected landing.

— Allegiant’s jets are, on average, 22 years old. The average age of planes flown by other carriers is 12. Experts say planes as old as Allegiant’s require the most rigorous maintenance in the industry. But of the 118 airports it flies into, Allegiant doesn’t staff its own mechanics at 107, including Bangor.

— Allegiant relies most heavily on McDonnell Douglas MD-80s, an aging model retired by all but two other major U.S. carriers. The company’s MD-80s fail twice as often as those operated by American Airlines and three times as often as those flown by Delta.

In Maine, Allegiant Air provides nonstop flights from Bangor to Florida’s Sanford-Orlando and St. Petersburg-Clearwater airports using MD-80 series and Airbus 319 and 320 jet aircraft.

To read the Times’ full story, go to tampabay.com/allegiant.