Less than two months after two possible weather-related fatal crashes of EMS helicopters in Illinois and Iowa, the FAA has issued a Special Airworthiness Information Bulletin covering recommendations for rotorcraft flying into snowy or icy conditions. The SAIB describes procedures to reduce the probability of an uncommanded in-flight engine shutdown due to snow and/or ice ingestion and reminds operators that most helicopters are neither equipped nor approved for flight into icing conditions.
The FAA recommends that airmen abide by their rotorcraft flight manual regarding flight into these conditions; conduct a thorough preflight weather evaluation; install engine inlet and exhaust inserts/covers whenever an aircraft is on the ground with engines not operating; refrain from prolonged engine idling/running while on the ground; thoroughly inspect inlets for ice/snow before takeoff; and remove any discovered ice/snow from inlets with either deicing fluid or heated air, not by chipping or scraping.
The FAA notes, “In freezing temperatures, pay particular attention to sheet ice on the bottom and forward of the inlet. This ice can also form behind particle separators. Engine preheating may be required.”