On July 8, 1989, a Piper PA-25-235 (registration N6941Z) was involved in an aviation accident near Goodway, AL. Investigators recorded the probable cause as: THE IN-FLIGHT SEPARATION OF THE LEFT WING WHICH FAILED BECAUSE OF A CORROSION INDUCED FATIGUE FRACTURE. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an aerial application flight, the left wing separated and the aircraft struck a house. Examination revealed a fatigue fracture originating at a rivet hole with intergranular corrosion.
Accident Overview
During an aerial application flight, the left wing separated from the aircraft. The aircraft subsequently struck the top of a house.
Examination Findings
Examination of the separated wing revealed a fatigue fracture in the wing's lower spar cap. Metallurgical analysis of the fracture surface showed that the crack initiated on opposite sides of a rivet hole. At one of the initiation sites, intergranular corrosion was present. The opposite initiation site had been mechanically mutilated, obscuring the original fracture features.
Previous Modification
In August 1977, all-metal wings were installed on the airplane under a Supplemental Type Certificate (STC).