The FAA issued a proposed rule on Tuesday that is aimed at reducing noise generated by new helicopters certified under Part 36 (noise standards) of the FARs. If adopted, the rule would impose standards already adopted by ICAO.

The new “Stage 3” standards would apply to all new helicopters in all phases of flight and be measured in Effective Perceived Noise Level in Decibels (EPNdB) for helicopters weighing more than 3,125 pounds. The new noise standards are constructed on a logarithmic formula based on mtows up to 176,370 pounds, while helicopters weighing 3,125 pounds or less would have a maximum noise limit of 82 decibels SEL.

The formula also sets a noise ceiling for helicopters that weigh 176,370 pounds or more during takeoff, flyover and approach–EPNdBs of 106, 104 and 109, respectively, for these phases of flight. Additionally, the noise formula decreases permissible noise at a rate of 3.01 EPNdB per halving of helicopter maximum weight to a floor of EPNdBs of 86, 84 and 89 during these same phases of flight for helicopters weighing more than 3,125 pounds.

Comments on the proposed rule are due by November 19.