Toro Rosso is still in the midst of its investigation into the suspension failure that pitched Brendon Hartley into the barriers in last Saturday's free practice session.
Initial analysis has not yet determined the cause for the breakage but a new component mounted on the suspension for the British Grand Prix weekend was ruled out as a potential source for the collapse.
"The component that we had the issue with was not a new spec," Toro Rosso tech boss James Key told Motorsport.com.
"As a precaution we went back to a previous spec of one part, even though it wasn’t associated with the failure that we had.
"The only reason we went back was only as an absolute precaution, let’s take any unknowns away, even though it didn’t appear to be associated with the failure."
Key insisted the team was completely taken by surprise by the failure.
"It is still being investigated and understood. We’ve never had any issues at all, certainly not of that nature. We did nine races without any problems," said the British engineer.
"Yes, we had some trackrod damage in Austria, but most people damaged their cars, and we had a particularly horrible thump on one of those kerbs.
“We haven’t seen anything like that, all the loads that were going through the front left suspension were well within the loads that it was designed for.
"That corner had a history, it had been used the previous day, it had been used in Canada, a big braking track, it had been used in Bahrain.
"It had been serviced and quality control checked, proof-tested, and everything was fine," he added.
"So it’s rather odd that we suddenly suffered an issue with a part that was perfectly normal, as far as we could see. What we need to establish whether there was some damage to it."
Key said that forensic analysis of debris is underway at Faenza, suggesting the failure was likely a one-off issue as Hartkey's team mate, Pierre Gasly, raced on Sunday without any problems to report.
"They’ve been sent back to the factory, they’ve all been quarantined, they will go through a forensic examination so that we can work out what is impact damage, what is potential failure, clues to how a failure could have occurred, etc. And we have various options to address any possible outcomes.
"We did a race with Pierre for 52 laps without any problems whatsoever, so it feels like a one-off, due to a set of circumstances that we need to understand, although you can never make assumptions like that."
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