At approximately 17:25 MDT, the pilot and passenger in a Piper Apache were killed when it crashed about one mile northeast of the Tucumcari Municipal Airport. The airplane departed Dallas, Texas, approximately 13:30 CDT, and was en route to Albuquerque. It landed for fuel at Tucumcari and was serviced with 54 gallons of fuel, then departed. At 17:17, the pilot advised Albuquerque Center that the left engine was smoking badly and that he was feathering the propeller. At 17:21, he advised he was returning to Tucumcari. The airport manager and the weather observer saw the airplane fly over runway 21 with the landing gear retracted. They radioed the pilot that his landing gear was still retracted, and the pilot replied that he would make a go around. The airplane was seen in a steep left bank before descending to the ground.