What is advantages and disadvantages of turnkey project?

advantages - it allows countries to share technological know-how, like middle eastern companies do not want USA and other countries to take part in their oil refining and want to profit from it themselves, but do not have the knowledge of the process, the Middle East enters into a turnkey project to gain the technological know-how.

disadvantages - you are automatically creating a competitor, if your technology is a source of advantage over competitors, allows this information is providing it to the competitor.