Effect of the New Insulation Liner on Noise Levels in the CH124B (Sea King) Aircraft
DEFENCE RESEARCH AND DEVELOPMENT TORONTO (CANADA)
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Crew members of the CH124B Sea King helicopter are exposed to elevated noise levels. To minimize noise levels as well as to insulate electrical wiring, the Sea King is equipped with a liner, which reduces noise. Recently the Sea King helicopters have been equipped with a new type of liner. Defence Research and Development Canada DRDC Toronto was asked to verify the noise levels in the Sea King during flight with the new liner and compare it with the old liner. Equivalent noise levels and octave band analysis were performed on a Sea King helicopter from Shearwater in February 5 and 6, 2008. Results showed that the new liner has absorption capabilities similar to or better than the old liner, except at the very low frequency of 8 Hz where absorption capability was lower for the new liner. Although at-ear sound pressure levels were not measured, it is reasonable to assume that they are acceptable with the new liner since they were acceptable with the old liner. Since sound pressure levels are significantly higher when the cargo door is open, it was recommended to open the door only for a short period of time to avoid excessive exposure for the crewmen and troops.