The Federal Aviation Administration (FAA) has proposed a $4m civil penalty against United Parcel Service (UPS) for alleged improper maintenance of four cargo aircraft. The FAA also alleges that UPS then operated the aircraft when they were not in compliance with Federal Aviation Regulations. The improper maintenance claims relate to a failure to follow FAA-approved procedures for making structural repairs to two DC-8 aircraft and two MD-11 aircraft. UPS operated the four aircraft on more than 400 flights between October 2008 and June 2009. UPS has 30 days from the receipt of the FAA's civil penalty letter to respond to the agency.