Incident
Shortly after takeoff, while the airplane was climbing through 12,000 feet, heavy black smoke appeared in the cockpit. The pilot declared an emergency and subsequently landed the airplane without further incident at a nearby airport.
Inspection Findings
A post-flight inspection revealed that the left side turbocharger clamp had separated through the tensioning band at the root of a spot weld. Subsequent microscopic examination of the area around the rim of the spot weld showed a crystalline appearance. An analysis of a spot weld from the right turbocharger clamp disclosed small recrystallized austenitic grains.
Maintenance History
The airplane's engine was installed in March 1991, and the turbochargers were replaced in June 1999. During the replacement, the turbocharger clamps were reused. The only requirement to change the turbocharger clamps was a mandatory replacement at engine overhaul.