Incident Description
During the approach to landing, the number six leading edge slat assembly failed. The inboard section of the slat hung down and bent aft. The pilot successfully landed the aircraft without further incident.
Post-Incident Examination
Metallurgical analysis of components revealed that a slat track roller bearing contained evidence of corrosion and spalling. Additionally, the slat track bearing bolt that had been installed through the aforementioned bearing exhibited heavy circumferential gouges on the surface of a cross-drilled hole at the areas of fatigue initiation. There was also evidence of tearing typical of damage produced during drilling with a dull drill bit.
Maintenance History
The airplane had completed a major structural maintenance check 48 flight hours and 28 cycles prior to the incident.