<< >> NASA ASRS Report 1150244, February 2014

A B757 crew reported uncommanded left and right yaw motions during climb with no EICAS or other malfunction indications so as a precaution; the crew returned to the departure airport

Attributes
ACN	1150244
Time
Date	201402
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Autoflight Yaw Damper
Person 1
Function	First Officer Pilot Flying
Experience	Flight Crew Last 90 Days 60 Flight Crew Total 12000 Flight Crew Type 4800
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 240 Flight Crew Total 20000 Flight Crew Type 3000
Events
Anomaly	Aircraft Equipment Problem Critical

Narrative:

On climb in VMC conditions; captain and I felt a noticeable left and right yawing motion of the aircraft. We had no yaw damper inoperative indications or EICAS indications. We initially thought maybe an engine issue but all indications were normal. We leveled off at 17;000 ft; turned on the autopilot but condition continued. We both agreed we did not want to take an unknown flight control issue any further and returned to the departure airport. Condition continued till landing.

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Original NASA ASRS Text

Title: A B757 crew reported uncommanded left and right yaw motions during climb with no EICAS or other malfunction indications so as a precaution; the crew returned to the departure airport

Narrative: On climb in VMC conditions; Captain and I felt a noticeable left and right yawing motion of the aircraft. We had no yaw damper INOP indications or EICAS indications. We initially thought maybe an engine issue but all indications were normal. We leveled off at 17;000 FT; turned on the autopilot but condition continued. We both agreed we did not want to take an unknown flight control issue any further and returned to the departure airport. Condition continued till landing.

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.