Carlo Reeker of Enercon says the cause of the failure was almost certainly a breakage of the kingpin which connects the nacelle with the tower. The cast-iron component, about a metre long and with a diameter of some 50 cm may have been substandard. Reports that bolts may have been at fault are not correct, he adds. No formal report has yet been issued on the incident as negotiations over insurance are still ongoing, Reeker says.
The failure occurred on one of the earliest E40 models to be built by Enercon at its Aurich works. The machine bears serial number 16 and was installed in January 1994. Enercon has identified a further 30 turbines which could be at risk from the same fault. These are now all being checked on site with ultrasound equipment, says Reeker.
Later E40 turbines are not at risk, adds Reeker. In the early days Enercon relied on the quality assurance of its component suppliers, but by April 1994, just three months after installation of the recently failed turbine, Enercon conducted its own ultrasound control of all cast iron components arriving at the works. If a doubt about quality arises, the parts are then X-rayed before being approved or rejected, Reeker says.