Barnhart was called upon by a customer to support the removal and replacement of three failed main bearings at a wind site in Kansas. The OEM Standard Operating Procedure called for the removal of blades, hub and drivetrain before exchanging the main bearing requiring multiple wind windows to perform. The variable weather conditions of a Kansas spring called for efficiency, so Barnhart engineered, designed and fabricated a rotor lifting methodology to remove the rotor and access the drivetrain in just two picks. This was the first time a rotor removal and replacement was performed on this turbine platform.
Barnhart’s fabricated lifting lugs, nicknamed “angel wings,” were attached to the hub and allowed for a single LR11000 crane to remove the rotor intact and downtail in coordination with a tail LTR 1220 crane. The team also designed a hanging power pack to provide electricity and hydraulics to the up-tower crews, saving them the need to run an umbilical 400 feet to the ground.
Adjustable rigging was also utilized, which enabled crews to locate an unknown center of gravity remotely from the ground.
Barnhart completed all three towers during the spring windy/muddy season in just seven weeks. Previous work on this site took approximately seven weeks per tower. Barnhart saved the customer money, reduced delays and executed the scope of work flawlessly, showcasing a safer and more efficient method.