On 25 November 2021, a Fokker F50 departing Helsinki experienced an engine malfunction which resulted in un-commanded propeller feathering following which the associated engine continued to run until shutdown during which time it began to overspeed. Recovery to a landing was subsequently achieved but the failure experienced was untrained and this led to both direct and indirect consequences which resulted in a sub optimal crew response to the emergency. The Investigation also highlighted opportunities to improve aspects of the air traffic control emergency response during such emergencies and identified language proficiency certification issues.