Natural icing flight tests were conducted on the EH-60A helicopter (USA S/N 86-24569) Quick Fix system to establish an icing flight envelope with the AN/ALQ-151(V)2 countermeasures system installed. Eight flights with a total of 11.1 productive test hours were flown in a natural icing environment at Duluth, MN between 25 February and 13 March 1989. Two deficiencies were noted: the design of the electronic countermeasures (ECM) antenna assembly and mount which caused excessive ice-induced oscillations and subsequent component failure and the poor reliability of the integrated inertial navigation system (IINS). Two icing-related shortcomings were noted: the loosening of the direction finding (DF) dipole antennas during flight in icing conditions and the inaccuracy of the liquid water content (LWC) readings of the Rosemount icing rate meter. The poor integration of the IINS and flight instruments which prevented the direct display of TACAN information was also a shortcoming. One previously identified icing-related deficiency and seven previously identified icing-related shortcomings of the UH-60A/EH-60A helicopter were re-evaluated and remain uncorrected. The EH-60A Quick Fix helicopter, with modified DF antenna insulator housing (part no. 1951-1-4116-4), should be released for flight in moderate icing conditions with the ECM antenna retracted only. The design of the DF antenna insulator housings should be improved to eliminate the requirement for maintenance after each icing flight. Keywords: AN/ALQ-151(V)2; EH-60A; Direction Finding Dipole (DF); Electronic Countermeasures (ECM); Antenna; Integrated Inertial Navigation System (IINS). (KT)


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