In a howling gale, Avon didn't take enough advantage in the first half with the wind at their backs. Rob Fitch converted early Avon pressure with a sweetly struck drop goal and skipper Kai Harwood finished off a series of close quarter drives with a try in the corner, magnificently converted by Fitch.
Avon threatened another score with firstly a scum on their opponents line, then a driving line out but were repelled with committed Chew defence and had to settle for another Fitch penalty for a 13 nil lead approaching the interval.
As the wind took a relieving kick too far across the home dead ball line, Chew suddenly found themselves with a scrum back inside the Avon 22 and took advantage of recycled possession to score a converted try under the posts from Alex Cox. In the same attack, 2nd row Richard Light suffered a broken ankle and both teams wish him well for his recovery.
The 13 - 7 Avon lead never seemed sufficient against the win and Chew made their opponents pay dearly as Cox added his second from a pick up and drive before dangerous fullback Tom Bryan escaped down the blindside for an outstanding try.
When Chew added their bonus point try through winger Silas Cox, they seemed to be cruising to victory. However Avon, with debutants Dan Ryan-Lowes and Tom Phillips to the fore, showed their spirit to come back strongly.
Although influential lineout specialist Scott a Book was forced to leave the field through injury, Ben Dilloway stole 2 line outs to give Avon an attacking opportunity on which they capitalised with a converted try from Fitch to close the gap to 26 - 20.
With Avon seeking to preserve their bonus point, Chew mounted a last ditch attack and were rewarded for their positivity with a final try in the corner by skipper Tom Waddington to seal the win in a game in a great advert for local rugby.
Next week Avon are at home to Midsomer Norton who defeated Berry Hill to move one point ahead of Avon in Western Counties North.