R44 - Mast Rocking

VIKTIG MELDING:
Robinson Working with FAA on R44 ‘Mast Rocking’Robinson Helicopter CEO Kurt Robinson said his company has been working with the FAA for “some time” to address concerns about “mast rocking” on its R44 helicopters. On Tuesday, the NTSB issued five safety recommendations (A-11-82 through -86) related to this condition in the wake of several accidents/incidents recorded since 2006. “We are working with the FAA to address any concerns or recommendations the NTSB has,” Robinson told AIN. Pilots of the incident/accident aircraft reported yaw and pitch oscillations severe enough to prompt them to make emergency landings, and several of them were “hard.” The condition appears to be exacerbated by a forward c.g. that can still be within the flight envelope and is more readily entered during left banking turns of 30 degrees. Flight test reports dating back to 2006 found that certain combinations of transmission mounts and vibration isolators mitigate the problem, as did adding power during autorotation. The NTSB recommends that the FAA require Robinson to resolve the “root cause” of the mast rocking, create a database of all related incidents, insert a warning in the flight manual and incorporate recognition and mitigation of the vibrations into its pilot training program. Foto: Robinson