I can’t explain why the manufacturer constructed this chart with the correct/incorrect shaded areas and the bizarre and convoluted path needed to determine a valid Power Assurance Check. The entire process could have been established with a much easier and less confusing process.
Regardless, if the vertical line derived from the bottom is to the LEFT of the vertical line derived from the OAT/Ng intersection, the engine is “CORRECT”.
Shawn, I have more info on this if you're interested.