In 2007, the Progress D-27 was successfully modified to meet the United States Federal Aviation Administration (FAA) Stage 4 regulations, which correspond to International Civil Aviation Organization (ICAO) Chapter 4 standards and were adopted in 2006.[67] A 2012 trade study projected that noise from existing open rotor technology would be 10–13 decibels quieter than the maximum noise level allowed by the Stage 4 regulations;[68] the newer Stage 5 noise limits (which replaced the Stage 4 regulations for larger aircraft in 2018 and mirrored the ICAO Chapter 14 noise standard established in 2014) are more restrictive than the Stage 4 requirement by only seven effective perceived noise decibels (EPNdB),[69] so current propfan technology shouldn't be hindered by the Stage 5 standards. The study also projected that at existing technology levels, open rotors would be nine percent more fuel-efficient but remain 10–12 decibels louder than turbofans.[68] Snecma, however, maintains that open-rotor tests show that its propfan engines would have about the same noise levels as its CFM LEAP turbofan engine,[70] which entered service in 2016.