BROOKLYN PARK, Minn. — Federal examiners tentatively ruled out engine failure re in a fatal crash at Crystal Airport. A preliminary report from the National Transportation Safety Board said no internal damage was found in the cylinders of the Beechcraft F33A. Also, the report said, the fuel system was functioning. The plane went down about 900 feet from the end of Runway 32 and exploded. Killed were the pilot, a retired Mayo Clinic orthopedic surgeon, and a North Dakota state legislator. The plane had arrived at Crystal Airport the day before on a 90-mile flight from Park Rapids and was heading back to Park Rapids. The pilot was aware of a problem just after take-off. He radioed the tower: “Abort, abort, 32X,” investigators said: A traffic controller cleared him to land on any runway. Video showed the plane banking left. On the ground a witness said the plane’s retractable landing gear was still extended at 150 feet up, which would be unusual. The video showed the plane, its engine still functioning, coming down almost vertically and nose first. Another witness told investigators the take-off itself did not appear abnormal but that the plane looked low and was not climbing normally.