For an airplane multi engine commercial rating:
If you are applying for a commercial pilot certificate with an airplane category and multi engine class rating, you must log at least 250 hours of flight time as a pilot (of which 50 hours, or in accordance with FAA Part 142, a maximum of 100 hours may have been accomplished in an approved flight simulator or approved flight training device that represents a multi engine airplane) that consists of at least:
100 hours in powered aircraft, of which 50 hours must be in airplanes.
100 hours of pilot in command flight time, which includes at least 50 hours in airplanes, and 50 hours in cross-country flight in airplanes.
20 hours of training on the areas of operation as listed for this rating, that includes at least 10 hours of instrument training of which at least 5 hours must be in a multi engine airplane, 10 hours of training in a multi engine airplane that has a retractable landing gear, flaps, and controllable pitch propellers, or is turbine-powered, one cross-country flight of at least 2 hours in a multi engine airplane in day VFR conditions, consisting of a total straight-line distance of more than 100 nautical miles from the original point of departure, one cross-country flight of at least 2 hours in a multi engine airplane in night VFR conditions, consisting of a total straight-line distance of more than 100 nautical miles from the original point of departure.
10 hours of flight time performing the duties of a pilot in command in a multi engine airplane with an authorized instructor on the areas of operation as listed for this rating, which includes at least one cross-country flight of not less than 300 nautical miles total distance and as specified, and 5 hours in night VFR conditions with 10 takeoffs and 10 landings (with each landing involving a flight in the traffic pattern) at an airport with an operating control tow