Accident Overview
Two witnesses reported hearing a loud noise from an aircraft in flight. Upon looking up, they observed that the left wing had failed. Subsequently, the aircraft entered a spin and crashed into a wooded area.
Examination Findings
An examination of the wreckage revealed that the left forward lift strut had failed approximately 6 inches from its attachment point to the fuselage. A metallurgical examination determined that the interior of the strut had become corroded, and the structure failed in an area where the wall had corroded to a knife edge, measuring less than 0.001 inch in thickness. For reference, the non-corroded portion of the wall was 0.38 inch thick.
A chemical test of the interior surface detected the presence of a corrosion inhibitor (Val-Oil) in the non-corroded areas. However, no inhibitor was found in the regions where severe corrosion had occurred. Additionally, two faint lines resembling water marks were observed inside the strut.
Maintenance Records
Logbook entries indicated that AD 77-03-08 and Piper Service Bulletin #528B had been complied with.
Toxicology
A toxicology test of the pilot's blood was positive for alcohol at a level of 0.04%. However, there was no indication that this was related to the strut failure.