Technical experts in France have begun examining a washed-up plane part that almost certainly belonged to missing flight MH370, raising hopes that some light may finally be shed on one of aviation's darkest mysteries.

The wing part is being examined in the presence of French, Malaysian, Chinese and American representatives at a military laboratory in the southern city of Toulouse after it was discovered last week on the Indian Ocean island of La Reunion.

The Malaysia Airlines jet disappeared on March 8 last year when it inexplicably veered off course en route from Kuala Lumpur to Beijing with 239 people on board, and a colossal multinational hunt for the aircraft proved fruitless.

But last week's discovery of the two-metre-long wing part called a flaperon raised fresh hopes for relatives desperate for answers.

The Boeing 777 piece has been taken to the south-western French city of Toulouse, where it will undergo the high-profile examination.

The case containing the wing part will be opened on Wednesday evening (Australian time), said a French source close to the case, in the presence of French and Malaysian experts, Boeing employees and representatives from China — the country that lost the most passengers.

It is as yet unclear whether their conclusions will be announced on the same day or later, added the source, who wished to remain anonymous.

Australia's deputy prime minister said official word on whether the flaperon was from MH370 was expected this week.

Analysis of paint, words and barnacles on flaperon

Jean-Paul Troadec, the former head of France's Bureau d'Enquetes et d'Analyses (BEA) that investigates air accidents, said the analysis would focus on two issues; whether the flaperon belongs to MH370 and if so, whether it can shed light on the final moments of the plane.

He pointed for instance to the paint on the piece, which has already been confirmed as coming from a Boeing 777 plane, as a key element of the probe.

"Every airline paints their planes in a certain way... and if the paint used is used by Malaysia Airlines and other companies, there may be more certainty," he said.

Pierre Bascary, former director of tests at the French Defence Procurement Agency, where the analysis will take place, added that the airline may have written maintenance information on the piece such as "Do Not Walk".

"The phrase used and the way it was written also gives an idea of the origin of the plane," he said.

Mr Troadec said experts would also examine the way the part detached itself from the wing.

"Was it in a violent impact with the sea or not?" he said.

"This piece looks like it is in good condition, it doesn't look like the part of a plane that fell vertically in the water at 900 kilometres an hour."

He added that experts may also look for traces of an explosion or fire.

Scientists have pointed to the barnacles that are attached to the flaperon, saying these could give an idea of how long the piece has been in the water, and perhaps where it has been.

"If it has cold water barnacles on it that might tell them it went down further south than they think. Or if it's got only tropical barnacles, that might tell them it went down further north," said Shane Ahyong, a crustacean specialist from the Australian Museum.

But he said some oceanic barnacles were so widespread that pinpointing their precise origin would likely be impossible given the lack of genetic and population information about them.

'One should not expect miracles'

Mr Troadec warned that the analysis was highly unlikely to give any clues as to why the plane mysteriously diverted off course.

"One should not expect miracles," he said.

For the victims' loved ones, though, any tangible piece of information is likely to help them in seeking closure, according to psychologist Carole Damiani, who specialises in helping the families of people who died in disasters.

"The grieving process is about untying oneself from someone, accepting that they will not be found and they have gone forever," she said.

"When someone goes missing, it is difficult to say 'I will stop looking'.

"You need people to say 'he is dead, you are allowed to start the grieving process and undo this bond'."

Ms Damiani said that knowing where the plane crashed would also bring some closure.

"When there is a 'natural' death, everyone always asks 'what were their last words, what were the last moments like?' And in this case, there is none of that. Families need to know how and why."

AFP