A fix has been devised for about one-third of the troubled blades and the manufacturing process has been changed, says Kenetech. The remaining two-thirds of the affected blades in Palm Springs are either being replaced as they are beyond repair, having cracked or delaminated during high winds, or are being used in a random check for additional problems. Of those that are being replaced, a "significant" number cannot be fixed, says Kenetech's Bud Grebey.
The problem had emerged previously when Kenetech acknowledged in late August replacing 37 faulty blades, 18 in Palm Springs and 19 at the more remote Buffalo Ridge site (Windpower Monthly, September 1994). But the extent of the replacement and repair only came to light more recently, when another blade in the closely-watched Palm Springs area suffered a massive failure on November 17 or 18. All that was left of a blade was a ten foot stump, say observers.
As of November 28, a fix had been applied to 57 blades, 30 from blade manufacturer, Ciba, in Washington state and 27 from Kenetech's long-time blade supplier, TPI of Rhode Island. The TPI fix was done in a small operation at a local industrial park. Thirty-one Ciba and 24 TPI blades had been replaced by the same date and another 57 TPI blades were awaiting replacement.
Kenetech Corporation vice president, Joel Canino, describes the failures as a "peel ply" problem during manufacturing. The seams of the blades were not bonding properly and a sanding step had to be added to the manufacturing process.
Additional Kenetech blade activity not linked to the "peel ply" problem is also under way in Palm Springs, notes Kenetech. Nineteen sets of blades, moved from where they were initially installed on 33M-VS turbines in the Altamont Pass, are being replaced. As of November 28, one new set had been installed and another 18 sets remained of those formerly in use in the Altamont Pass.