Can you just sue anyone for anything?
But being able to sue falls nowhere near being able to win.
To sue literally means to deliver properly formatted papers to the court, pay the fees, and deliver copies to the other party. Bingo! You are already suing!
Then what? That's the real question.
Since you have no contract with the engineer, your only recourse is to sue in the tort of negligence. However, such a suit will fail. The engineer does not owe you a duty of care given their overriding duty to their principal. That is, their duty to their client overrides any theoretical duty they owe to you. The issue might be different if you can prove ...