The Federal Aviation Administration is seeking a $4 million penalty from UPS for not complying with federal safety rules. The FAA says UPS did not follow federally-approved procedures for maintaining four planes, which allegedly went on more than 400 flights in 2008 and 2009. The agency further says UPS has not entirely complied with an agreement that required the company to check aircraft repairs against maintenance records. The FAA says had UPS followed the agreement, the penalty would not be necessary.In a statement issued Wednesday afternoon, Transportation Secretary Ray LaHood says "The aviation industry knows that we take safety very seriously. Air carriers must comply with federal regulations to ensure aircraft are maintained to the highest level of safety.” FAA Administrator Michael Huerta adds, “No aircraft should leave the ground until the operator has made all necessary repairs, and made them according to the correct procedures."UPS spokesman Mike Mangeot says the suggested penalty is “unwarranted and unreasonable." "UPS has a long history of operating a safe, compliant airline," he says. "There was never a safety issue. We believe we were compliant with FAA rules and will vigorously defend our position.”UPS has a month to officially respond to the FAA.You can read the FAA's full letter to UPS here.