Part 91 - General operating and flight rules. (Private)
Part 121 - Operating requirements: Domestic, flag, and supplemental operations (Legacy Airlines, Regional Carriers)
Part 125 - Certification and operations: Airplanes having a seating capacity of 20 or more passengers or a maximum payload capacity of 6000 pounds or more, and rules governing persons on board such aircraft.
Part 129 - Operations: Foreign air carriers and foreign operators of US registered aircraft engaged in common carriage. (International operators)
Part 133 - Rotorcraft external load operations. (Helicopters)
Part 135 - Operating requirements: Commuter and ondemand operations and rules governing persons on board such aircraft. (Charters)
Part 137 - Agricultural aircraft operations. (Crop Dusters)