Toro Rosso investigating "odd" Hartley suspension failure

Although the team was running a new specification of suspension part on the STR13 at Silverstone, it wasn’t directly associated with the component that failed, which was of original spec.

However, as a precaution, Pierre Gasly went back to the complete older spec for qualifying and race, and had no problems.

The spare chassis was built up for Hartley for Sunday, also with old-spec suspension, but a systems issue before the start meant that he ran only one lap before retiring.

“The component that we had the issue with was not a new spec,” technical director James Key told Motorsport.com. “As 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 said the failure had come as a complete surprise to the team.

“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.

"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. 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.”

The pieces of debris retrieved after the crash are now being examined.

“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.

“Brendon was extremely unfortunate, it was obviously nothing to do with him, but it very negatively affected his whole weekend. But he was fine, which is the most important thing, and the car did exactly what it was supposed to do in an impact of that nature.”

Key said Hartley's early retirement in the race was a consequence of the team having to build up his STR13 in so little time.

“The mechanics did a fantastic job of getting it back together from scratch, because it really was a complete car build overnight.

"We had other issues which were a knock-on effect of the fact that we had to rebuild the car – a systems issue that didn’t show itself in fire-ups, but did show up in proper reconnaissance laps.

"That caused us to delay going out of the pits. We got out half a lap down, but the problem was still there.”