As a continued emphasis on rotorcraft and icing conditions, the FAA has issued a Special Airworthiness Information Bulletin alerting owners and operators of turboshaft-powered rotorcraft of the possibility of inflight engine loss of power due to the ingestion of ice and/or snow.
Accumulation of ice and/or snow can occur in the area of the airframe engine inlet while the rotorcraft is on the ground or in the air. At this time, this airworthiness concern is not an unsafe condition that would warrant airworthiness directive (AD) action under Title 14 of the Code of Federal Regulations (14 CFR) part 39. However, this SAIB describes procedures to reduce the probability of an engine in-flight shutdown due to ice and/or snow ingestion.
MOST helicopters are not approved or equipped for flight into icing conditions.
Be sure to read the ice and/or snow Special Airworthiness Information Bulletin.