There's been a rumour that Chevron would be forced to change to twins for nearly 25 years. That's why Bristow got rid of the Jet Rangers and replaced them with Twin Stars on the old Topcon contract in 1991 (that's when Texaco and Chevron were still separate companies). However, PAAN just continued with the 206s out of Escravos. The 412s are getting old now and Bristow is desperate to find someone willing to take the S76D. I doubt that will be Chevron.