The Indian manufacturer was forced to withdraw Lucas di Grassi and Oliver Rowland in South Africa, as well as the customer Abt cars of Nico Muller and Kelvin van der Linde due to the issue.
Bertrand confirmed the problem centred around a wishbone on the rear suspension which had failed on both Mahindra machines and one of the Abt vehicles after FP2, leaving the teams no choice but to withdraw from the event.
“It was a mix between three things,” Bertrand told Autosport ahead of the Sao Paulo E-Prix this weekend.
“Probably spec was a little bit under what was needed. Manufacturing, probably some imperfections, and on top of that a track which was so demanding and bumpy and fast, and not giving any real chance for any mistake, and that’s also really what guided the choice.
“Maybe on some tracks you could say let’s take the risk and then we will see. But on that one, the comparison between the level of risk and the impact of the risk was too high, that’s why we went to the extreme decision.
“The correct decision, you never know which one will be the correct decision. I think it was the most reasonable considering the different parameters, the type of track we were racing on and the level of risk which our drivers would have been exposed to. You cannot play with that side.”
Bertrand stated that the problem had a reasonably simple fix and only needed two-and-a-half weeks to implement, and is confident no such issues will impact the teams in Brazil this weekend.
He said: “We needed a good two-and-a-half weeks to do the full process, from the reproduction of the fault to the moment you identify the good solution, you check that the solution will be consistent and sustainable, and then you go to production of parts.
“It’s the good and the bad thing of what happened. It was a quite a basic problem and probably due to under estimation in the development in the level of constraints and also in the validation plan we had, which was not robust enough.
“Definitely confident [the problem is fixed] and definitely happy.”
