A small plane had mechanical problems with its autopilot system before it crashed in Arkansas last month and killed a former Mississippi state senator who was flying it, according to a preliminary report by the National Transportation Safety Board.

Johnny Morgan, 76, of Oxford, Mississippi, served in the Mississippi Senate from 1984 to 1992. He was the only person aboard the twin-engine Beech King Air E-90 plane when it crashed May 17 in a wooded area in northwestern Arkansas, south of Fayetteville.

The NTSB said Morgan had contacted an avionics repair facility at Drake Field Airport in Fayetteville to discuss the plane’s autopilot problems. A technician told Morgan to bring the plane in for service and to not use autopilot during the flight. Morgan planned to fly to Fayetteville and leave the plane at the avionics facility for maintenance, according to the NTSB.

The crash happened just over an hour after the plane took off from University-Oxford Airport in Oxford, Mississippi.

The NTSB said plane’s descent was nearly vertical, based on damage to the plane and trees.

“Both engines and propellers were embedded in the terrain, and the entire airplane was fragmented,” the NTSB report said. The agency’s investigation of the crash continues.