Sound pressure levels inside the cabins of the AS350 B2 and AW119 MkII rotary-wing aircraft during SAR operations

High SPLs inside helicopters are of concern, but, to date, there is very little specific data on noise exposure of helicopter crews in SAR and aeromedical missions. In aeromedical and rescue operations crew and patients are subject to flight configurations that are very different from that performed by conventional aviation. Operation inside the "Dead Man's Curve", with live cargo hanging, close to the MTOW or open doors is frequent. As flight patterns directly influence interior SPLs, more detailed noise measurements inside helicopters during such operations are required. To investigate the internal noise patterns of the public helicopter fleet of the state of Santa Catarina'a AS 350 and AW 119 models during Rescue and Transport missions, four different AS 350 B2 and one AW 119 MkII were equipped with recording equipment (microphone and SQuadriga II) and flown repeatedly under mission-specific operational conditions. Mean LpAeq in AS350 aircraft (8 measurements) ranged from 89dBA@40kt to 95dBA@110kt (doors closed [DC]) and 95dBA@40kt to 99dBA@110kt (left rear door open). LpAeq standard deviation ranged from 1dB @different speeds to 3 dB @60kt. Mean LpCeq in AS350 aircraft (8 measurements) ranged from 106dBC@40kt to 110dBA@110kt (DC) and 117dBC@40kt to 124dBC@110kt (left rear door open). LpCeq standard deviation ranged from 1dB to 3 dB. In the AW119 (3 measurements) mean LpAeq ranged from 95 dBA @40kt to 102dBA@140kt (DC) and 96dBA @40kt to 99dBA@80kt (both rear doors open). Mean LpCeq ranged from 106dBC@hovering OGE to 119dBC@140kt (DC) and 108dBC@hovering OGE to 116dBC@different conditions (rear doors open). Standard deviations were 1 to 6dB, largest at take-off. Flying with open doors increased A-weighted SPLs up to 7 dB in AS350B aicraft and 9 dB in AW119 aircraft. Increase of C-weighted SPLs was found to be up to 15 dB in AS350 and 6dB in AW119.