Le Mans 24 Hours: Cause of Loic Duval's crash still unknown

when his Audi R18 e-tron quattro became airborne and slammed into the debris fencing ahead of the final right-hander in the Porsche Curves.

Allan McNish, who works with Audi's drivers following his retirement from the cockpit, said: "What happened is speculation at the moment, and we are not into speculation.

"We need to speak to Loic in detail when the time is right and do a proper analysis."

McNish stressed that the other two R18s were "checked thoroughly for technical problems" before returning to the track when practice restarted approximately 50 minutes after the accident.

There could be similarities between Duval's accident and that which befell then-Peugeot driver Marc Gene at the Le Mans test day in 2008. He got on the grass exiting the second part of the double left in the Porsche Curves and took off.

The distinctive shark fin of LMP1 machinery was introduced for 2011 in an attempt to prevent cars taking off after a spate of incidents at the end of the 2000s.

Duval was kept in hospital in the city of Le Mans overnight for observation and is expected to be released this afternoon.

McNish confirmed that Duval, who escaped from the accident with cuts and bruises, never lost consciousness.

The Frenchman , a decision that was taken by the FIA medical delegate and race organiser the Automobile Club de l'Ouest's doctors after consultation with medical staff at the hospital.

ACO sporting manager Vincent Beaumesnil said: "Loic is OK, but after a big shock like that he would not have been ready to drive today [in qualifying]. He needs to rest."

The #1 Audi, which Duval was due to share with Tom Kristensen and Lucas di Grassi, is being built up around a new monocoque.

McNish reported that at 8:30am this morning, the car "looked to be in exactly the same stage of preparation as the other two cars".

Audi has been given dispensation by the race stewards to recall test and reserve driver Gene from the Jota Sport Zytek LMP2 team and place him alongside Kristensen and di Grassi in the #1 car.

Jota has brought in Oliver Turvey, who raced with the team in last year's European Le Mans Series, to drive its Zytek-Nissan Z11SN with Harry Tincknell and Simon Dolan.

The FIA-spec debris fencing seriously damaged by the Audi was not replaced after Duval's accident for the remainder of practice and then qualifying.

Beaumesnil explained that it was not mandatory at this point of the circuit because its primary purpose was to protect the public (and this area is not a spectator zone).

It will be replaced in time for when qualifying resumes at 7:00pm local time tonight.

Follow all of this weekend's action from the Le Mans 24 Hours with AUTOSPORT Live - coming from our team of reporters at the circuit