What happened
While the aircraft was in flight, two witnesses reported hearing a loud noise. Upon looking up, they observed that the left wing of the aircraft had failed. Following this structural failure, the aircraft entered a spin and crashed into a wooded area.
The investigation
An examination of the wreckage identified that the left forward lift strut had failed approximately 6 inches from its attachment point to the fuselage. A metallurgical analysis revealed that the interior of the strut had undergone significant corrosion. Specifically, the metal wall had corroded down to a "knife edge," measuring less than 0.001 inch in thickness, whereas the non-corroded portion of the wall measured 0.38 inch.
Chemical testing of the internal surface of the strut showed that a corrosion inhibitor, known as VAL-OIL, was present in the areas that had not undergone severe corrosion. However, no traces of the inhibitor could be found in the areas where the severe corrosion had occurred. Investigators also noted two faint lines within the strut that resembled water marks.
Review of the aircraft logbooks indicated that compliance with AD 77-03-08 and Piper Service Bulletin #528B had been maintained. Additionally, a toxicology report for the pilot showed an alcohol concentration of 0.04%, though investigators found no evidence linking this to the structural failure.