NTSB Identification: SEA01IA161.
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Scheduled 14 CFR operation of HORIZON AIR INC
Incident occurred Tuesday, August 28, 2001 in Portland, OR
Probable Cause Approval Date: 06/03/2002
Aircraft: de Havilland DHC-8-102, registration: N827PH
Injuries: 3 Uninjured.

NTSB investigators used data provided by various sources and may have traveled in support of this investigation to prepare this aircraft incident report.

The operator reported that shortly after departure the first officer noted stiffness in the flight controls when attempting to roll the airplane to the left. After assessing the situation, the captain elected to continue the climb. Shortly after level off, the crew noted that the stiffness increased proportionally with airspeed. This was also noted during the descent phase of the flight, specifically, the first officer stated the resistance increased for left roll inputs as the aircraft accelerated. The captain reported that they attempted to relieve the pressure with aileron trim, however, when the trim indicator reached the first index on the indicator, the control wheel "snapped" approximately 25 degrees and the airplane banked to the right. The crew reported that as the airplane slowed, while on approach, the roll control stiffness decreased. After landing, the crew accomplished a full control check and noted no abnormal indications with the ailerons or spoilers. Post flight inspection disclosed a number of discrepancies that are believed to have contributed to the stiff flight controls. The items are as follows: the right control yoke chain tension was high; the right aileron spring tab hinge bearing did not rotate freely; the left aileron spring tab aft spring tension was low and the contact stud was worn; the right aileron spring tab tension was low and the contact stud was worn; the left aileron hinge bearing did not rotate freely.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

Improper tension of the right control yoke chain; a worn right aileron spring tab hinge bearing; improper tension of the left aileron spring tab aft spring and worn contact stud; improper tension of the right aileron spring tab and a worn contact stud; a worn left aileron hinge bearing.

Full narrative available

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