A report by the Transportation Department inspector general said there were concerns one low-fare carrier expanded its fleet by 56 percent, tripled its number of destinations and increased operations by 59 percent from 2000 through 2003 while it reduced its mechanic workforce by 14 percent.
However, the FAA and airlines -- who are ultimately responsible for safety -- denied increased competition and maintenance outsourcing were causing safety breaches, the Washington Post said Thursday.
"We're extremely mindful of these changes" in the airline industry, said Margaret Gilligan, the FAA's deputy associate administrator for aviation safety.
United Airlines, for example, closed some of its maintenance facilities to save money but said it retains oversight of its major contractors, both of which are in the United States.
"We have our own maintenance folks who are on site who review the work the vendor is doing," United spokesman Jeff Green said.