Racing Point says the failure that prevented Nico Hulkenberg from taking part in Sunday's British Grand Prix was traced to a sheared bolt located in his car's clutch housing.
Subbing for the quarantined Sergio Perez, Hulkenberg minutes away from joining the grid when his Racing Point crew was unable to properly fire up his RP20's Mercedes engine.
A quick diagnosis revealed the loose bolt, but a lack of time prevented the team from solving the issue.
"It looks like a bolt sheared within the clutch housing," said team boss Otmar Szafnauer.
"And that bolt got caught and therefore wouldn't allow the internal combustion engine to turn over. So where the bolt fell off, it got jammed, and we couldn't turn the engine over.
"I think it's a bit early to understand why, but it did shear off so it could be a material issue, it could be an over-torque issue, I don't know.
"I'm sure all of those bolts are torqued to a certain specification, say the torque ratio isn't set right and you over-torque it, it could shear it.
"It could be a material issue in manufacturing, but until you look into all of those things - was the bolt brittle for example, I don't know - so we'll have to understand the root cause and make sure we fix it."
Szafnauer said that the bolt was part of the Mercedes PU package, and not a component supplied by Racing Point.
The pink squad's boss lamented not having two cars in the race but also Hulkenberg's missed opportunity to gain valuable race mileage.
"It would have been very useful for Nico to get a race in," he said.
"Unfortunately he didn't. I think he did a great job jumping in the deep end, starting from zero really, he didn't do any winter testing, didn't understand the car at all, it's a different car than he drove before, a different powertrain.
"The team is similar to when he was here, but he still had a different engineer as his old engineer is on Lance's car, but the rest of the guys he worked closely with, so he did a remarkable job.
"It was a steep learning curve, he did great to qualify where he did and it's a shame he didn't get to race."
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