As Lotus prepares for the final pre-season test, technical director James Allison, explains why the team had to pull out of last week's test, whilst insisting that he is confident the problem has been resolved.

"We arrived in Barcelona with a brand new chassis," says the Englishman. "We completed installation laps on Tuesday morning then Romain (Grosjean) left the pits for his first run of the day. As soon as he touched the brakes before turn 1 on his first flying lap, he felt that something was wrong. He told us on the radio that he was aborting that run and returning straight to the pits. We saw immediately that we had a problem with the mounting of the upper front wishbone rear arm.

"We were using chassis 02 for the first time," he continued, "so our initial reaction was to consider the possibility of a manufacturing issue affecting that particular chassis. We made the decision to take chassis 01 - which had run successfully in Jerez - from the UK to Barcelona. Before we sent it, we launched an investigation programme at Enstone to ensure there was no risk of a similar issue. Unfortunately, our investigations concluded that there was a possibility of the same problem reoccurring. We then decided, quite reluctantly, to cancel the test and make the necessary changes to both our chassis before running again.

"It's been an intense few days," he admitted, "but I have to say that everybody has completed their tasks in tremendous fashion. On the first day back at the factory, I spoke to the entire Enstone personnel and clearly explained what happened. Everybody understood that the situation was unfortunate, but under control. We designed the new parts, manufactured them, and fitted them to the chassis. We then completed the necessary tests satisfactorily and the chassis left for Spain."

Asked if he is confident about the repair, Allison has no doubts, "Yes," he replies. However, he reveals that the car is now slightly heavier. "We're only talking about 1kg, which is manageable," he says. "It won't have any significant impact on handling or performance."

Having confirmed, contrary to speculation, that the chassis did not have to undergo another crash test, he adds: "We'll use chassis 01 this week, while chassis 02 will be used as a spare from now on. We're currently finishing chassis 03, with the new design implemented."

"Missing four days of testing is not ideal," he replies when asked if missing the Barcelona test was a set back. "We need mileage at this stage of the year, as does any other team. That said, there are reasons to remain optimistic. First of all, we completed many trouble-free laps in Jerez and gained a good understanding of the car. Also, some of the small issues we identified in Jerez needed to be fixed, and the parts were not available last week.

"On Thursday, the car will run with all the required redesigned parts. We're looking forward to being back on track."