This can throw the propeller, bearings, turbine, or other drivetrain components out of alignment, then they wear and fail prematurely. To stiffen the tower without adding much weight, the company called on Lord Corp., Cary, N.C. (, to adapt one of its Fluidastic dampers.

The damper can bleed off more than 50% of 300,000-lb loads, despite short strokes. It provides bidirectional damping at frequencies from 0.25 to 0.45 Hz, the band that caused resonant vibrations in the tower. The dampers should last 20 years without maintenance.

Circle 402