The next generation of aircraft could be thinner and lighter thanks to the development of a nonlinear acoustic imaging technique that can detect damage previously invisible to acoustic imaging systems. According to Dr. Jack Potter, research assistant in the department of mechanical engineering at the University of Bristol’s Ultrasonics and Non-destructive Testing research group, it has long been understood that acoustic nonlinearity is sensitive to many physical properties including material microstructure and mechanical damage.
Business aircraft cabins are generally not quiet. Not with the turbulent boundary-layer rush of air around the fuselage at Mach 0.85 and the whine of a couple of jet engines no great distance from the comfy chairs. Then there are the pumps, hydraulics, fans, gears, actuators, electric motors, worn bearings and air distribution through the metal ductwork, not to mention the occasional hum of the microwave and induction oven, the rattling of glasses and flatware in the galley and that giant sucking sound coming from the lavatory.
Sennheiser’s updated active noise cancellation HMEC 26-2 headset adds comfort, noise protection and a higher sound pressure level to the HMEC 26. To improve the fit for a wider variety of pilots, Sennheiser redesigned the two-piece automatic headband so it can be opened another 20 degrees. Restricting folding of the ear cups to a 45-degree angle improves wearing stability. The microphone boom is made of a new steel that remains in the set position more securely, according to Sennheiser.
Today at EBACE, Nextant Aerospace launched the $4.95 million 400XTi (the “i” stands for innovation) as the latest evolution of its remanufactured Beechjet. Compared to the 400XT, the new version introduces a number of improvements, including an all-new cabin that offers more space and reduced noise.
Chemical giant BASF is claiming its Basotect open-celled melamine foam is both improving sound insulation and saving weight in the Russian Helicopters Mi-8. Used for an executive cabin refurbishing, it has cut interior noise from 85 to 80 dB. It has also saved 530 pounds, compared with the previous insulation arrangement. The special foam is affixed to “selected noise-intensive points,” at a thickness of 40 mm.
Under pressure from a pair of local high-profile congressmen, Howard Berman (D) and Brad Sherman (D), the FAA has announced it will hold a community hearing on helicopter noise in the L.A. basin during the first week of August. The hearing will take testimony from concerned parties that will be the basis of a report that could provide the basis for imposed and/or voluntary solutions.
E-A-R Thermal Acoustics Systems (Stand 2145) is improving acoustic insulation aboard business jets as it endeavors to cut the most annoying cabin noises on a case-by-case basis.
Smac Aero of Toulon, France, continues to develop new technology aimed at reducing aircraft cabin noise and promoted its full line of noise-reduction technology in Cannes, France.
Among the latest items is the SmacBarrier, an acoustic layer designed to reduce the transmission of sound generated around window trim panels, flooring and ceiling panels.
Also fresh off the development line is SmacFoam, specifically created to reduce sound transmission and provide sound absorption in smaller, confined spaces.
InspecTech Aero Service has launched its iShade iQ electrically dimmable window, and the new technology includes a breakthrough in noise damping, according to the Fort Lauderdale, Fla.-based company. “Cabin windows are a main path for noise transmission,” explained the company at the Aircraft Interiors Expo in April in Hamburg, Germany.
There are “tens of thousands of aging military aircraft” flying with the world’s air forces and many of those aircraft are more than 25 years old, according to Rob McDonald, ASIS marketing director. “Many of these fleets are set to be still flying in 20 years or more, with some aircraft, such as the USAF KC-135 tankers, topping 80 years old before the last aircraft is withdrawn from service,” he said.
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