What happened
On 9 February 2019, a Cessna 208B Caravan, registered PK-FSS, was performing a scheduled passenger flight from Tanah Merah Airport to Oksibil Airport in Papua, Indonesia. The flight was operated by PT. Spirit Avia Sentosa with two qualified pilots and four passengers on board.
While climbing through 6,500 feet, approximately 20 nautical miles from the departure airport, the crew experienced a sudden and unexpected acceleration of the aircraft. Upon checking engine parameters, the pilot monitoring noted high torque of 2,400 psi, an Inlet Turbine Temperature of 920°C, and gas generator speed at 109%. In an attempt to stabilize the aircraft, the pilot in command moved the power lever to the idle position; however, while the lever moved freely, the engine power remained unresponsive and could not be reduced.
Recognizing the danger, the crew decided to return to Tanah Merah Airport. The pilot executed engine failure emergency procedures and, as the aircraft approached the airfield, manually shut down the engine. The aircraft landed safely on runway 25. There were no injuries to the passengers or crew, and the aircraft sustained no damage during the incident.
The investigation
The KNKT investigation focused on the mechanical failure that allowed the engine to remain at high power despite the power lever being at idle. Key components, including the Fuel Control Unit, Fuel Pump, and Propeller Governor, were removed from the engine and sent to the Pratt and Whitney Canada facility for detailed examination. This analysis is being conducted in coordination with the Transportation Safety Board of Canada.
Findings
- The aircraft was operating under a valid certificate and was maintained using the Maintenance on Reliable Engines (MORE) system.
- There were no recorded system malfunctions prior to departure.
- The primary issue was an uncontrollable engine power increase that persisted even when the power lever was moved to the idle position.
- The crew successfully managed the emergency by transitioning to a planned engine shutdown and executing a safe landing.