ATR Delivers Peace and Quiet
“You’re in the noisiest seat of the airplane,” said ATR North America sales vice president to an AIN reporter, who had chosen the position to assess that very thing during an ATR 72-500 demonstration flight late last year. Another guest on board the 68-seat twin turboprop was Adrian Wijeyewickrema, manager of consulting services for Back Aviation Solutions of Washington, D.C. He chose row seven to fly abeam the six-bladed propeller and the new Pratt & Whitney Canada PW127M engine for the same reason.
ATR promises that “optimum synchrophasing” between the props should deliver comfort while in turbulence. The company provided an inadvertent demonstration during several phases of that 40-minute flight through clear-air chop over Washington Dulles Airport.
Wijeyewickrema said he was surprised at the quietude next to the Hamilton Standard 568F propellers, though less so by noise levels aft. ATR has also made available its improvements in the -500 series cabin noise relative to earlier models.
Overhead bins, which provide 40 percent more volume than in previous examples of the ATR 72, include a molded handrail for those walking the aisle. Bins are attached with special dampers to cut the transmission of structural noise to the interior. In addition, an in-flight entertainment system now sprouts from beneath the bins.
Cabin partitions are treated to reduce the reverberation to the front and rear, and insulation blankets are adjusted for thickness and made waterproof. Frames near the propeller have been stiffened and the blade vibration muted by the addition of “dynamic vibration absorbers” on the upper sides of frames as well as on the floor beams. The ATR’s skin is treated for damping with viscomaterial strips to reduce noise propagation.
ATR provides an example of a 200-nm route, claiming that on that journey the ATR 72-500 burns 12 to 16 percent less fuel per passenger than a typical two-passenger European automobile. The ATR 72-500 can be configured to hold up to 74 seats, but the standard is 68 at a 31-inch pitch.
The aircraft is also predicted to emit 50 percent less carbon dioxide (CO2) per passenger-mile than new-generation regional jets, while the PW127M engine and higher lift design allow four more passengers at ISO range.
In flight overhead, the ATR 72-500’s noise footprint is measured at an EPNdB of 90 and contained to 1.2 square miles versus 2.1 square miles for a regional jet. The ATR flies at a lower level and so may yield less harm to the upper atmosphere, according to the company.
The cabin is generously bright, given more windows than rows of seats, but individual reading lights are also provided. The -500’s new “Elegance” cabin lessens the energy draw using LED interior lighting for a diffused and gentle effect. ATR has said the coming 42-600 and 72-600 will include such LED lighting for both external navigation and anti-collision lighting to increase their lifespan as well as to enhance the visibility of the aircraft.