On April 3, 1995, a DE Havilland DHC-8-102 (registration N828MA) operated by Mesaba Aviation was involved in an aviation accident near Moline, IL. Investigators recorded the probable cause as: the defective weld and the subsequent in flight failure of the welded plug located in the piston of the roll spoiler actuator. The manufacturer's inadequate design is a related factor. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 2 related events involving the same aircraft type or operator are linked below.
During approach, left inboard roll spoiler jammed partially deployed. Landing uneventful. Post-incident revealed welded plug in servoactuator piston had separated. Manufacturer reported prior failure and redesigned piston.
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.