What happened
On 6 August 2020, an Airbus MBB BK117 D-2 helicopter, registration PK-JBX, was conducting type-rating flight training at Bersujud Airport in Batulicin, Indonesia. The flight was part of a training program for PT. Jhonlin Air Transport pilots, led by an instructor and two student pilots.
Following a series of successful training exercises, including autorotation and a tail rotor failure simulation, the instructor took control of the aircraft to return to the apron. As the instructor applied right pedal to turn toward runway 09, the helicopter suddenly entered a clockwise spin, rotating three times. To regain control, the instructor engaged the autopilot system and performed an immediate landing on the runway. Following the landing, an emergency shutdown was executed. While the crew evacuated safely without injury, the helicopter sustained substantial damage, including significant dents and tears to the lower fuselage skin and landing cross tube.
The investigation
The KNKT examined flight data from the Cockpit Voice and Data Recorder (CVDR) and the Appareo Vision 1000 Flight Data Recorder Information (FDRI). Analysis of the CVDR revealed that during the incident, wind speeds had increased to approximately 24 knots before returning to calm. The data also tracked the rapid fluctuations in the helicopter's magnetic heading during the spinning motion. The investigation also reviewed the aircraft's maintenance status, finding it airworthy prior to the flight, though it noted an unserviceable radio altimeter. The investigation is ongoing to further examine flight techniques and potential human factors.