Barry Controls Aerospace's Active Tuned Mass Absorber (ATMA) has been selected by Northwest Airlines to reduce cabin noise in its 173 McDonnell Douglas (MDC) DC-9s.
The system has been on trial with the airline for two months and was selected after a competitive evaluation against a noise-suppression system produced by Lord. The ATMAs replace MDC-built vibration absorbers and reduce structure-borne noise by detecting the actual engine vibration frequency, processing the data and optimising the absorbers to connect to the engine frequency.
The contract award coincides with the granting of a US Federal Aviation Administration supplemental type certificate on 16 April, covering the use of the device on all marks of DC-9s and MD-80s. Installations of the system, which reduces overall and tonal noise by up to 90% at the noisiest rear seats, are due to begin in June. The full fleet is expected to be retrofitted by June 1998.
Source: Flight International
