Certification and Operation of Helicopters in Icing Environments

Abstract

This paper presents the issues gathered from a survey carried out on helicopter airframe and engine manufacturers, and helicopter operators and aircrews, throughout Europe and Canada. The work focused on in-e ight icing and the problems of manufacturing, testing, and subsequently, operating helicopters in such conditions. Most commercially operated helicopters are not permitted to e y in known icing conditions, because they are not certie ed to do so by the aviation authority. However, during the survey it was established that owing to commercial pressures, aircrews do e y in icing conditions, using helicopters that do not have an icing clearance. In addition, there is a disparity between what the airframe manufacturers and icing specialist know are the most dangerous icing conditions, and the knowledge held by helicopter aircrews. Aircrews would like a better method of ice detection and would prefer an ice predictor, which indicates that an icing environment is approaching, rather than a detector, which tells them that they are already in icing. Furthermore, operators would like all helicopters to have a full icing clearance if there were no operational penalties. In conclusion, the industry as a whole would like to verify that the icing envelope described in the certie cation regulations is applicable for helicopters. The current parameters have been modie ed from e xed-wing aircraft, which tend to cruise at much higher altitudes and in colder, drier conditions.