Citation Excel (C560XL)
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Returned To Departure Airport; Flight Crew Landed in Emergency Condition; General Declared Emergency
Aircraft
[Shortly after] takeoff at about 300 FT AGL the ACM O'HEAT came on followed by the left BLD AIR O'HEAT. There was black acrid smoke in the cockpit and the cabin. Due to the fact we were in a critical phase of flight and at low altitude; we turned the pressure source to OFF and declared an emergency. We entered the downwind and configured for landing. The Captain briefed the passengers over the intercom. When we were abeam the numbers the smoke started to lessen. After landing we cleared at the first available taxi way; performed an emergency shut down. While the Captain performed the shutdown the First Officer evacuated the passengers. We gathered about 100 FT in front of the aircraft and let the Fire Department check the plane. There was no fire detected.
[Narrative 2 had no additional information.]
CE-560XL flight crew reported shortly after takeoff they had ACM O'HEAT and BLD AIR O'HEAT messages; as well as black smoke in the cockpit and cabin. They declared an emergency; returned to departure airport; and evacuated the aircraft.