Narrative:

Rudder fail cas message followed by dutch roll induced by light turbulence. Unable to maintain altitude or airway. Initially [requested special handling] as dutch roll increased in intensity. Requested block altitude initially; but ATC did not understand this request. Requested lower altitude and descended to FL301. Was able to stabilize the dutch roll and reconnect autopilot. Followed QRH procedure; but rudder remained completely failed including trim function; discussed options for landing airport and diverted to ZZZZ due to favorable wind conditions and weather. Completed safe landing at ZZZZ about 1:40 after initial event. Flight control computers were operational hydraulics were all operational remote electronic units 15 and 16 were both failed along with rudder lvdt disconnect.

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Original NASA ASRS Text

Title: Gulfstream G650 Captain reported that Rudder Fail CAS message followed by Dutch Roll required a diversion to a suitable airport.

Narrative: RUDDER FAIL CAS message followed by dutch roll induced by light turbulence. Unable to maintain altitude or airway. Initially [requested special handling] as dutch roll increased in intensity. Requested block altitude initially; but ATC did not understand this request. Requested lower altitude and descended to FL301. Was able to stabilize the dutch roll and reconnect autopilot. Followed QRH procedure; but rudder remained completely failed including trim function; discussed options for landing airport and diverted to ZZZZ due to favorable wind conditions and weather. Completed safe landing at ZZZZ about 1:40 after initial event. Flight control computers were operational hydraulics were all operational Remote Electronic Units 15 and 16 were both failed along with Rudder LVDT Disconnect.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.