Chappell marked his first PGA Tour start since November 2018 following microdiscectomy surgery on his back by entering the record books in West Virginia.
There was little sign of what was to come during his first round, however, as he carded a 1-over 71 on his return.
However, he surged up the leaderboard on Friday, including posting nine successive birdies after opening with a par at the 10th.
Mark Calcavecchia is the only other player on the PGA Tour to record nine straight birdies and, though Chappell was unable to take sole ownership of the record, he was able to make further gains at the fifth and seventh.
“I’ll be completely honest — I’ve been pretty uncomfortable for two days,” he told the media after his superb round.
“I’m just kind of getting back into the swing of things, it’s not as innate as I thought it was to get back out there and compete.
“But I really enjoyed it and embraced it today. Obviously, seeing the ball go in the hole, you can really embrace being uncomfortable.”
His remarkable showing moved Chappell into fifth place, three strokes behind leader Scottie Scheffler.
