The Malibu, although a single engine piston, is a very complex aircraft, pilots transitioning from an A36 Bonanza or Cessna T-210 are in for a big surprise. This airplane demands constant training, recurrent training and requires respect. If the encoder, as shown by the transponder readout, kicks offline and the last info sent was that the aircraft is at 41,400 feet it tries to return the aircraft to where it originally was told to go, i.e., the altitude pre-selected. Basically when the preselector is dependent on information sent by the encoder. I was aware when the phenomenon was about to occur, and therefore prepared for the pitch deviations.
Pilots unaware have no prior warning.
Upon having an avionics shop look at the possible problem, they reported that the encoder may have a problem running four lines off of it, possibly that the lines have crossed or that there maybe a voltage problem. If the pitch-over occurred in turbulent or IFR conditions, or both, the pilot may not have noticed until the airspeed was observed. In a split-second decision, if the pilot tried to pull out of the dive without disconnecting the autopilot, the autopilot would try to compensate for the pilots input and put it into a steeper dive. The fact that the rate controller feature of the KX-297B automatically defaults to the steep descent rate profile may also be suspect, I feel that if the Preselector would have leveled off the aircraft or defaulted to zero in case of an uninstructed disturbance, the autopilot would not try to chase it. The fact that the crashes could have been linked to pilot error, or improper decision making may be relevant, but this airplane requires pilots to understand super critical airfoils, the understanding of high-altitude operations and autopilot theory and application.