The Bell 525's Smooth Ride

The Bell 525 Relentless is designed to fly farther and faster than any previous Bell commercial helicopter. The increase in flight time means that vibration and internal noise are more significant elements to crew and passenger comfort. To address crew exposure to these factors, the 525 employs a three-tier strategy for reducing vibration and structure-borne acoustics. The approach first reduces the transmissibility of source vibrations from entering the airframe. Secondly, the airframe structure natural modes are desensitized from the rotor excitation frequencies. Third, remaining vibrations are treated with vibration reduction equipment. While this strategy was successfully used in the design of the Bell 429, the 525 Relentless takes this approach to the next level through lessons learned from the 429, improvements in the pylon design, and incorporating technology advancements in active vibration reduction. With first flight of the 525 Relentless in July 2015, envelope expansion through 200 knots airspeed has demonstrated the success of this three-tier strategy with vibration levels that set the standard for the industry.