Incident Description
On November 7, 2011, a Boeing B767-300 experienced a warning during the takeoff roll at Katowice Airport (EPKT). After increasing power for takeoff, a yellow caution message appeared on the upper EICAS display: LEFT YAW DAMPER. The crew rejected the takeoff at a speed of 47 knots. The rejected takeoff did not pose any threat to the safety of passengers or crew. The captain informed the chief flight attendant and the tower controller (TWR) of the situation. After taxiing to taxiway D and stopping the aircraft, the captain requested assistance from the Maintenance Control Center (MCC). The MCC suggested taxiing to the jet bridge. The captain informed the passengers of the need to do so. After engine shutdown, the maintenance team cleared the aircraft for flight under MEL 22-21-01. During the subsequent takeoff and entire flight, the malfunction did not recur.
Findings and Cause
On November 12, 2011, the defect was rectified by replacing the Control Pressure Switch S29 in accordance with AMM 29-11-19. Appropriate tests of the left and right yaw dampers were performed and passed successfully. The cause of the incident was a malfunction of the Control Pressure Switch S29 in the yaw damper system.
Actions Taken
The operator replaced the Control Pressure Switch S29 as per the Aircraft Maintenance Manual (AMM 29-11-19) and conducted the required tests. No safety recommendations were issued by the investigation commission.