ISTANBUL, May 8 (Reuters) - McLaren's Heikki Kovalainen thanked his lucky stars and paid tribute to Formula One's safety standards on Thursday after being passed fit to race at the Turkish Grand Prix following his big crash in Spain.

The Finn was knocked out and taken to hospital suffering from concussion after ploughing into the tyre wall in the Spanish Grand Prix on April 27.

The governing International Automobile Federation (FIA) said they had given the 26-year-old the all-clear for Sunday's fifth round of the season after a mandatory medical at the Istanbul Park circuit.

Kovalainen told a news conference he still had no recollection of the accident at the Circuit de Catalunya, although he had seen it on television.

"It was a serious accident and I managed to walk away," he said. "I think I was a little bit lucky but I must stress that all the safety standards that the FIA has been pushing worked very well.

"I think it (safety) is something that we must still keep working on, but the work paid off that day."

Kovalainen's car penetrated the barrier in Barcelona after spearing off the circuit at around 240kph when his front left tyre deflated.

The car hit the tyre wall at about 130kph, with the driver experiencing a deceleration equivalent to 27g, or 27 times his body weight. The team confirmed on Thursday that the accident had been caused by a wheel rim failure.

MOTHERS' DAY

Declaring himself 100 percent fit, Kovalainen said the medical was the same as the one he took when he made his Formula One debut in Australia last year - only this time he did better "so the impact seems to have had a good effect".

He questioned, however, whether he had really lost consciousness in the accident.

"The people who arrived at the scene first reported that I was awake and assisting getting myself out of there, but I don't have any memory of that," he said.

"After such a hit in the head it's a bit of a shutdown from the body to protect your brain and organs," he added. "It would be good if one day the whole image came back... but at the moment all I can tell is what I saw on the video."

Kovalainen said his first real memory was from the hospital.

"I remember being in intensive care in the hospital in the city (with) a lot of people around me," he said.

"I was a bit confused (about) what had happened so I asked my team doctor, 'What are we doing here?', and he explained what happened. Then after that the memory has been normal and I was aware of everything after that. That's where I got back on track."

Sunday is Mothers' Day in Finland and Kovalainen hoped to give his mum a better present than the shock she had from Spain.

"She was working while I was racing and my dad called her and said 'Heikki had an accident', and she was, like, 'Okay'. Then she got home and actually saw what happened and went a bit crazy," he said. "But she's just about recovered now.