Kurt Busch might have signed up with Phoenix Racing to just have some fun in 2012, but it seems that his notorious temper is still not far from the surface - and landed him in trouble again at Darlington Raceway at the end of last Saturday's Southern 500 NASCAR Sprint Cup Series event.

The original incident started when Kurt Busch blew out a tyre and spun the #51 car while running in the top ten with six laps remaining in the race; Ryan Newman was also involved in the incident. Fuming at the lost opportunity, Busch came on to pit road for a costly stop and exited his pit box in an angry burnout and plumes of tyre smoke that took him through Newman's pit box - where members of the #39 crew were still out working.

"When you come ripping through someone's pit box like that, he could have took out five or six guys plus the officials pretty easy," said Newman's Stewart-Haas Racing crew chief Tony Gibson. "I don't know how somebody didn't get run over, to be honest with you. It was just a miracle somebody didn't get hit."

That set off a row between Busch and Newman's pit crews, with Newman's refueller Andrew Rueger storming down to Busch's hauler to wait for him at the end of the race, leading the Phoenix team to get onto Busch over the team radio to tell him to park the car at the entrance of pit road after the race rather than risk a physical altercation. In the meantime, the situation worsened when Busch made contact with Newman out on track after the chequered flag: Busch said it was accidental, but Newman thought otherwise.

"It's easy to see and it's easy to say that Kurt blew a fuse again ... I think that he lied and was so frustrated that he doesn't know how to deal with his anger," said Newman. "I'm not sure why he did it and tried to run over our guys and NASCAR officials."

The Newman crew rushed to where Busch has parked to confront him, with a NASCAR official sent tumbling as organisers tried to break up the confrontation and Busch himself was restrained by his pit crew and pulled away from the fracas.

As a result of the incident, NASCAR's regular scheduled Tuesday post-race announcements included a slew of penalties for the people involved - with Kurt Busch top of the list getting a $50,000 fine for reckless driving on pit road during the race and being involved in an altercation with another competitor (Newman) after the completion of the race. Busch was also placed under formal probation through to July 25.

One of Busch's #51 personnel, motorhome driver Craig Strickler, was also fined $5,000 and placed on probation through to the end of the year for "interfering with a member of the broadcast media" after he tried placing his hand over the lens of a camera recording the incident.

On the Newman side of the incident, Tony Gibson was put on probation through to June 27, as the crew chief is deemed by NASCAR to be held accountable for the actions of his personnel on pit road even though he himself was not personally involved in any of the actions.

And gas man Andrew Rueger was also fined $5,000 and put on probation for the same amount of time as Gibson for failing to comply with instructions from the NASCAR officials during the incident. However, NASCAR said this was not for sending their official tumbling during the incident, which they had decided was just an accidental stumble.

"He might have tripped and stumbled with a shove from another crew member or whatnot," was the view of Busch's crew chief Nick Harrison.

The hefty fine and probation for Busch caught many pundits by surprise, as NASCAR usually takes a "Boys, have at it" approach to incidents during the race; if an action is considered beyond the pale then it's usually dealt with immediately during the race by a penalty of black flag.

Instead, it seems that Busch's previous notorious conduct led NASCAR to decide that his minor collision post-race with Newman was most definitely intentional and then to retroactively roll in the pit lane burnout into their deliberations before handing Busch his fine and probation, even though the driver himself was not directly involved in the subsequent pushing and shoving between the crews.

Last year, the Southern 500 saw an altercation between drivers Kyle Busch and Kevin Harvick out on track that ended up with Harvick trying to punch Busch through the window of the #18 on pit road. That sparked a season-long feud between Kyle Busch and the whole Richard Childress Racing stable.