US Army UH-60M Helicopter Main Rotor Ice Protection System 2007-01-3301

Sikorsky Aircraft Corporation designed a new advanced technology composite main rotor blade for a growth BLACK HAWK helicopter, now designated the UH-60M. The UH-60M main rotor blade has new airfoils, a larger blade chord, and a swept, tapered, anhedral tip, with a rotor ice protection system (RIPS) similar to that of the UH-60A/L helicopter. The UH-60A/L RIPS control system was retained and the new blades were fitted with heater elements similar in geometry to those of the UH-60A/L main rotor blades, but with the outboard extent of the heater mat 10 inches more inboard than that of the UH-60A/L and the woven wire heater resistance was changed to maintain the same power density as the UH-60A/L. Analyses and S-92A® helicopter artificial and natural icing flight test data show that the increased blade chord, improved airfoils, and advanced blade geometry result a minimal change in BLACK HAWK icing flight characteristics. Therefore, the flight test program to qualify the UH-60M for flight in icing conditions was limited to a brief US Army natural icing flight test program to confirm the analyses and to establish a safe icing envelope for the UH-60M BLACK HAWK helicopter. The US Army conducted nine flights in the vicinity of Sawyer International Airport near Marquette, Michigan, from 10 November through 13 December 2005. Cloud immersion time was 6.8 flight-hours during the 18.6 flight-hour test program. The test aircraft was flown in the normal utility configuration with no external fuel tanks at true airspeeds ranging from 220 to 237 km/hr. The static air temperature during natural icing encounters varied from -2.5 to -20.0°C and the liquid water content ranged from 0.15 to 0.60 g/m³. Capabilities of the ice protection systems, consequences of ice accretions, and performance and handling qualities in the icing environment were considered during these tests. Based on analyses, the results of the UH-60M icing tests, and the results of previous icing tests of UH/EH-60A and S-92A helicopters, the UH-60M is considered safe for operation in icing intensities through moderate icing (up to 1.0 g/m³).