On September 21, 1991, a Piper PA-25-235 (registration N7509Z) operated by Wallace Flying Service was involved in an aviation accident near Brewton, AL. Investigators recorded the probable cause as: Failure of a wing front spar fitting clevis ear due to corrosion from chemical spraying, and absence of an inspection procedure for that area. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
The left wing separated from the airframe when a wing front spar fitting clevis ear failed. Corrosion between welded sections, attributed to chemical spraying over time, caused the failure. No inspection procedure existed for that area.
Separation
The left wing separated from the airframe when one of the two wing front spar fitting clevis ears failed.
Examination Findings
Examination of the failed component uncovered corrosion between the sections making up the welded clevis ear. The accumulation of corrosion was attributed to chemical sprayed from the airplane over a long period of time. Additionally, no inspection procedure was specified for this area of the wing fitting.
NTSB Recommendation
Subsequently, the NTSB issued a recommendation requesting an inspection procedure to prevent the formation of corrosion between the layers of clevis material.
Probable cause
Failure of a wing front spar fitting clevis ear due to corrosion from chemical spraying, and absence of an inspection procedure for that area.