What happened
Shortly after departing, the pilot elected to return to the airport to retrieve forgotten paperwork. The pilot reported that the approach and touchdown were normal; however, during the landing roll, the left main gear collapsed. Following the collapse, the aircraft veered off the runway and struck a runway light before coming to a stop.
The investigation
An examination of the left landing gear revealed that the left main landing gear trunnion had failed near the fillet web due to fatigue. The trunnion had been in service for 1,255 hours of operation.
A Piper service bulletin (#787A), dated August 15, 1985, recommended that after 1,000 hours of service, the trunnions be inspected at intervals not exceeding 100 hours of operation until they are replaced. These inspections were required to be performed using a 10-power magnifying glass after all paint and dirt had been removed from the component. While the trunnion had been inspected 55 flight hours prior to the accident, the operator reportedly failed to properly remove paint and dirt before conducting that inspection.