This is not an insurance issue or a valid claim. This is a design flaw.
As a general rule, when an engineer negligently performs services on behalf of his firm or employer, the individual allegedly suffering damage from the engineer’s negligent performance may sue the company and/or the individual engineer. Typically, in the case of an engineering firm in private practice, the firm’s professional liability insurance carrier will respond to claims against any past or present principal, partner, director, officer, or employee acting within the scope of their duties.
http://www.nspe.org/ProfessionalLiability/LiabilityEmpEng/index.html