A US family of six, who survived a plane crash that killed 40 people in Peru last month is planning to sue plane maker Boeing for unspecified damages, alleging a design fault, their lawyer said on Saturday.

Manuel von Ribbeck of the Nolan Law Group, represents the Vivas family from New York state.

He told CPN radio the suit would be filed next week in Chicago, home of Boeing's headquarters.

"There is a series of design and manufacturing flaws in this plane which make the company responsible, even if that did not cause the accident," von Ribbeck said.

The suit will also include United Airlines, which trained the crew, he said.

Boeing spokeswoman Liz Verdier said she could not comment in detail until the company saw the suit.

The Boeing 737-200, which crashed on August 23, was operated by the Peruvian state airline TANS.

The cause of the accident has not yet been established, but Von Ribbeck said poorly designed seats prevented many passengers from escaping.

"Emergency lights didn't work, emergency ramps didn't open and the emergency doors didn't open completely," he said.