"His brutal death is a great loss," said French President Emmanuel Macron.
French billionaire politician Olivier Dassault died on Sunday in a helicopter crash in France's northwestern region of Normandy, parliamentary and probe sources told AFP.
The 69-year old MP from right-wing party Les Republicains was the grandson of Marcel Dassault, the founder of giant aircraft manufacturer Dassault Aviation.
French President Emmanuel Macron paid tribute to the lawmaker on Twitter.
"Olivier Dassault loved France. As a captain of industry, a local elected official and a reserve commander in the air force: throughout his life, he never ceased to serve our country, to promote its assets. His brutal death is a great loss. Our thoughts go to his family and loved ones," the French leader wrote.
The accident took place during take-off around 6pm local time in the town of Touques, a probe source told AFP.
There was no one else on board the aircraft besides Dassault and the pilot, the same source said.
Public prosecutor Delphine Mienniel confirmed both were dead.
"We are opening a judicial investigation for involuntary manslaughter," she told AFP.
Olivier Dassault was the 12th wealthiest person in France with a net worth of €6.3 billion, according to the Bloomberg Billionaires Index.