What happened
A certificated flight instructor was conducting a turbine transition training flight for a second pilot. The aircraft involved, a modified aircraft equipped with a Pratt & Whitney PT6 turbine engine, was undergoing instruction to familiarize the student with the characteristics of turbine powerplants compared to piston engines.
During the approach to runway 31, the instructor noted that the propeller governor control was causing the engine to surge. As the aircraft neared touchdown, the engine experienced another surge while the second pilot was manipulating the flight controls. This resulted in a sudden loss of performance, leading the aircraft to stall and land hard on the runway. The pilot reported that during previous landing attempts in the same session, the student had failed to maintain sufficient power to prevent hard landings.
The impact caused substantial damage to the airplane's fuselage.