About 110 employees walked off their jobs on Oct. 14 after failing to reach contract agreements on medical benefits and other issues.
The union has accused the company of trying to undermine the walkout. Plant manager Mike Spears sent a letter urging technicians to return to work as non-union workers.
Sikorsky spokesman Ed Steadham said the union has received the company's best and final offer. He also said administrative personnel is being used to fill in for striking employees.