"Billings Flying Service was founded by brothers Gary and Al Blain, who in 2014 bought the nation’s first civilian-owned Chinook helicopters and fitted them for fighting wildfires and hauling heavy equipment. The shop they have to maintain the helicopters and service other air equipment is substantial."
I think what the article's author meant was that Billings Flying Service is the first civilian owner/operator of the CH-47D, because, If my memory is correct, ERA Helicopters was the first American civilian owner/operator of the Chinook. The model they operated was the CH-47C, or otherwise known as the Boeing-Vertol 234. ERA serviced oil rigs in the Bering Sea and supported other operations along the Aleutian Chain of Islands.
Cheers,
Grog