The session was red-flagged to a stop.
The front left wheel of his auto lifted and skewed vertically as the suspension collapsed and he was left without control of the machine as it spun backwards heavily into the barriers.
Raikkonen dug deeper on his next run, producing a 1m27.199s lap to wrestle top spot back from Hamilton with just under 15 minutes of the hour remaining.
Hamilton, a five-time victor at Silverstone, posted a best lap of 1:26.722 seconds around the 5.891-kilometre course but Kimi Raikkonen of Ferrari was just 0.093 seconds behind.
After this point, the Directorate has suspended the session, and the track arrived ambulance.
He walked away from the incident, and was given the all-clear to drive following checks at the medical centre.
Hartley was speeding down Silverstone's Wellington Straight at around 200mph when his front-left suspension buckled as he hit the brake into Brooklands, removing the tyre, and he was merely a passenger as the auto went into the gravel and into a big impact with the barrier.
"He's a bit shocked, but OK", said Hartley's team mate Pierre Gasly, whose vehicle was thoroughly checked afterwards for signs of any similar suspension problem.
Aside from Leclerc, only Haas pair Kevin Magnussen and Romain Grosjean were able to get within two seconds of the time achieved by pacesetter Hamilton, as they classified eighth and ninth respectively.
Marcus Ericsson capped an encouraging session for Sauber by rounding out the top 10, in front of Force India duo Esteban Ocon and Sergio Perez, with Fernando Alonso the lead McLaren driver in 13th spot.
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