Artificial Icing Test, Utility Tactical Transport Aircraft System (UTTAS), Boeing Vertol YUH-61A Helicopter
ARMY AVIATION ENGINEERING FLIGHT ACTIVITY EDWARDS AFB CA
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An in-flight artificial icing evaluation was conducted of the YUH-61A helicopter equipped with a prototype deice system. During the test program 3.2 hours were flown in the artificial icing environment. Of this time, 2.8 hours were flow with the deice system functioning, and 0.4 hour was flown with the system not functioning. Anti-ice systems for the engines, engine air induction systems, pitot tubes, and windshields were used during all flights and functioned satisfactorily. With the deice system not functioning, ice accretion on the airframe and flight control surfaces caused significant increases in power required for level flight and significant decreases in autorotational rotor speed with collective full-down. Also noted were increased airframe vibration levels caused by random asymmetrical shedding of ice from the main rotor blades, and damage to the tail rotor blades and transmission fairing caused by ice impact. These adverse results preclude safe operation of the YUH- 61A in an icing environment without a main rotor deice system. With the deice system functioning, the YUH-61A successfully flew in artificial icing conditions simulating moderate icing. Three deficiencies were noted which should be corrected prior to flight in icing conditions. These deficiencies are the inability to activate the deice system following an ice detector malfunction the lack of a system to monitor the integral particle separator turbine operation and the erratic and unreliable pitot-static indications in level and climbing flight caused by the irregular ice accretion patterns on the lower fuselage nose area.
- Transport Aircraft