Summary
We propose to adopt a new airworthiness directive (AD) for Turbomeca S.A. Arriel 2C1, 2C2, and 2S2 turboshaft engines. This proposed AD was prompted by a report of a helicopter experiencing a digital engine control unit (DECU) malfunction during flight. We are proposing this AD to prevent loss of automatic control on one or both engines installed on the same helicopter, which could result in an uncommanded in-flight engine shutdown, forced autorotation landing, or accident.