Four Maine airports are getting federal grants to improve their facilities. The Federal Aviation Administration is awarding $2.6 million to the Bangor International Airport, $1.4 million to the Portland International Jetport, $850,000 to the Knox County Airport in Owls Head and $509,000 to the Princeton Municipal Airport. The Bangor airport will use the money to improve the runway drainage system, upgrade runway lights and enclose a drainage canal that attracts wildlife. The Portland Jetport will use the grant for two front-end loaders, two snowplows and a snow-sweeping vehicle. The Knox County Airport will use the money for a new plow truck and to install a fence around the airport perimeter to keep wildlife off the runways. In Princeton, the grant will fund construction of a new taxiway for planes to access the main runway.