The Air France plane crashed off the northeast coast of Brazil on June 1, 2009. The Airbus plane dropped into deep waters, beyond the reach of radar and sonar. (CBC)

French investigators say they've found wreckage from an Air France jet that crashed off Brazil's coast almost two years ago with 228 people onboard.

This marks a fourth attempt at locating the flight and data recorders. As of late Sunday, French officials would only reveal that the wreckage had been found in the past 24 hours.

Flight 447 had been flying from Rio de Janeiro to Paris when it went down on June 1, 2009, in a thunderstorm. Parts of the plane have been recovered but not the wreckage containing the flight data recorder — or black box — with important technical and voice information.

Locating the main body of the plane has proven difficult because it crashed into deep waters, beyond the range of radar and sonar. To conduct the actual search, planes and ships rely on sonar signals from the black box.

The findings are crucial because a French judge recently handed down a decision allowing preliminary manslaughter charges against Airbus, which manufactured the plane. Airbus is the world's largest airplane producer.

The $12.5-million US search is jointly financed by the airline and by Airbus, which produced the plane. Airbus says the true cause of the crash will never be known until the flight and data recorders are found.

The French accident investigation agency BEA is overseeing the search but the technical component is being run by the U.S.-based Woods Hole Oceanographic Institution, which has participated in the previous searches.

The search involves a 10,000-square kilometre area, several hundred kilometres off Brazil's northeast coast. More than $28 million US has been spent on previous searches.

Some airplane experts have suspected the crash was caused by false air speed readings from the pitot tubes — sensors on the underbelly of the Airbus 330-200.

Air France CEO Pierre-Henri Gourgeon said his company had taken measures to fix faulty sensors. French investigators have also said it's likely the crash was caused by not one but several factors.