On March 4 the FAA issued its final rule on Stage 3 helicopter noise certification standards for new helicopter type design and the upgrade of Stage 1 and Stage 2 helicopters when upgrading to Stage 3 via supplemental type certificate (STC). The rule standardizes FAA regulations with those adopted by the International Civil Aviation Organization (ICAO) in 2002 and follows the issuance of a notice of proposed rulemaking (NPRM) on the topic issued in 2012.
Under the new rule, helicopters with an mtow of 3,125 pounds or less cannot produce noise in excess of 82 dB SEL (decibels, sound exposure level) at the maximum normal operating rpm during takeoff, flyover or approach.
For heavier helicopters the noise limit is calculated using the formula of 3.0 db SEL per doubling the weight after 3,125 pounds. For helicopters having an mtow of 176,370 pounds or more the Stage 3 limits are as follows: takeoff 106 EPNdB (effective perceived noise decibel level–a calculation that is “annoyance based” and takes into account both frequency and audibility), 104 EPNdB for flyover and 109 EPNdB for approach. In all three phases of flight the limits decrease by 3.0 EPNdB per halving of weight down to a floor of 86 EPNdB for takeoff, 84 EPNdB for flyover and 89 EPNdB for approach.
The rule amends Part 36 of the FARs to allow new helicopter type designs to be designated Stage 3 compliant under the ICAO standards. The FAA notes that the final rule does not impose incremental costs and carries the benefit of quieter helicopters manufactured and certified under the new standard, with the assumed benefit that they will then be easier to market outside the U.S. The FAA notes that the rule does not impose any new costs, since “testing procedures for helicopter noise certification already exist and will not change when certifying a helicopter to Stage 3 standards.”
The final rule does not require existing, noisier Stage 1 and Stage 2 helicopters to meet Stage 3 standards. The Helicopter Association International (HAI) and other trade groups had fought for this position. At the time of the release of the NPRM in 2012, HAI president Matt Zuccaro said, “Helicopters are major capital investments, so we also believe any FAA action should include a grandfather clause for existing helicopters to allow them to continue to fly for the remainder of their operational lives, and that the new noise certification standards should not affect access to airspace for legacy aircraft.”
Helicopter noise is measured by direct acoustic sampling and calculation that accounts for both the frequency of the noise and its “annoyance” factor.
The FAA began looking at the issue of helicopter noise in 1973 as more advanced sampling and measuring technologies became available. The agency issued its first NPRM on the subject in 1979, but later withdrew it. In 1982, helicopter manufacturers and NASA began cooperative research on helicopter noise-abatement technologies. In 1988, the FAA adopted its first helicopter noise regulation as an amendment to Part 36 of the FARs and similar to ICAO Annex 16.
The U.S. Congress has long been embroiled in the issue of helicopter noise, most recently directing the FAA to develop noise-abatement policies and routes in Los Angeles if voluntary measures fail to quell noise complaints within one year. In 2012, enacted federal legislation directed the FAA and the National Park Service (NPS) to devise financial incentives for air-tour operators who use quiet technology helicopters over the Grand Canyon. That incentive took effect on January 1 this year, and operators of quieter helicopters will see their per-flight fee over the park reduced to $20 from $25. An NPS spokesman said the reduced fees will save tour operators $250,000 per year.