Limited Artificial and Natural Icing Tests Production UH-60A Helicopter (Re-Evaluation)

A limited re-evaluation of the production UH-60A Black Hawk anti-ice and deice systems was conducted to verify correction of deficiencies and shortcomings which were revealed during 1979-1980 icing tests. Testing consisted of 22.3 productive flight hours. The previous droop stop deficiency (failure of the droop stops to return to the shutdown position with ice accumulation on the rotor head) was corrected by the installation of a different droop stop with anti-ice protection. The previous anti-flapping restrainer deficiency (failure of the anti-flapping restrainers to return to the shutdown position with ice accumulated on the rotor head) was downgraded to a shortcoming after correction of the droop stop deficiency. The three most important previously identified shortcomings (1) the large increase in power required with ice accumulation on the rotor system, (2) the large power available losses with activation of the engine and engine inlet anti-ice systems, and (3) the poor location of the deice system circuit breakers, were again documented, although some improvement in power available losses was observed due to installation of the modulating engine inlet anti-ice valves. Five other previously identified, icing related, shortcomings were still present and four were corrected. Three additional icing related shortcomings were identified during these tests: (I) ice impact damage to the upper strobe light assembly, (2) ice impact damage to the nose avionics compartment door, and (3) the poor reliability of the windshield anti-ice control units. The UH-60 Black Hawk helicopter, configured with the anti-ice, deice and heated government competitive test droop stop systems demonstrated safe operation in icing intensities through moderate.