The US Federal Aviation Administration (FAA) is considering slapping United Airline and US Airways with fines running into millions of dollars. Both airlines are accused of violating safety regulations.

A whopping $5.4 million dollar fine has been proposed for US Airways, for operating eight aircraft on 1,647 flights between October 2008 and January 2009. The airline is said to have violated both standard aviation industry safety regulations, as well as its own maintenance rules.

United Airlines may face a similarly impressive fine of $3.8 million. The airline is said to have flown one of its Boeing 737 planes on over 200 flights, with nothing but shop towels capping openings where oil is discharged at the bottom of the engine. Standard safety regulations as well as the airline’s own maintenance codes require these to be capped with dedicated, protective caps.

While the proposed fines are large, it may be that the figures could be reduced after negotiations. The FAA rules allow the airlines 30 days to present evidence on their own behalf.  The hefty sums quoted in the proposed flights reflect the number of flights that the airlines operated while violating safety regulations, and are not linked to the number of passengers on board.