Incident Description
During the approach to the destination airport, the pilots reported that the left inboard roll spoiler jammed in the partially deployed position. The aircraft landed without further incident.
Post-Incident Examination
A postincident examination of the roll spoiler system revealed that the fusion welded plug in the piston of the roll spoiler servoactuator had separated. This separation caused the spoiler to remain partially deployed, preventing full retraction.
Manufacturer's Report
The manufacturer reported that there had been one previous failure of a welded plug in a servoactuator piston. In response to these failures, the manufacturer has since changed the design of the piston to eliminate the welded plug entirely, thereby addressing the underlying mechanical issue.