NTSB Identification: ANC98IA004.
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Nonscheduled 14 CFR
Incident occurred Monday, October 20, 1997 in KASIGLUK, AK
Probable Cause Approval Date: 11/10/1998
Aircraft: Cessna 208B, registration: N9304F
Injuries: 1 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

The pilot was entering a left downwind for landing at a remote airport. The wind conditions were 25 knots with gusts to 35 knots. During the turn, the pilot utilized full aileron deflection, and noticed the aileron momentarily jammed. He was able to force the control wheel to the right, unjamming the aileron. After landing, the pilot began to taxi to the ramp. Due to a strong crosswind, the pilot deflected the ailerons fully to the left. The aileron once again jammed, and the pilot was unable to force the control wheel to the right. The airplane's ailerons utilize balance weights that are attached to the interior surface of the leading edge of the aileron. Five screws are inserted through the leading edge skin of the aileron, through the balance weight, and into self-locking nuts attached to a nut strip assembly. Company maintenance personnel reported 1 screw was missing. Three of the remaining 4 screws were loose, and backed out sufficient distance to contact the trailing edge of the wing, forward of the aileron. The left aileron was jammed in a full, leading edge down, position. The Cessna 208B pilot information manual details a preflight inspection that includes an examination of the ailerons as part of a walk-around inspection of the airplane. In addition, the balance weights should be inspected during every 100-hour inspection. A review of the manufacturer's service condition report data base, and the Federal Aviation Administration malfunction and defect report system did not reveal any other reported incidents of aileron jamming.

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

inadequate inspection of the aileron by company maintenance personnel, and the pilot's inadequate preflight inspection of the aileron, which led to the jamming of the left aileron due to loose balance weight retaining screws.

Full narrative available

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