Thank you John.
I don't see any "promises" in either Part 23 or Part 25 ...
True enough. Slack wordiology on my part.
Vmcg (and Vmca, for that matter) are artificial certification animals...
I think the phrasing of my question and the title distracted from the real issue -- sorry. What I want to know is: "What certification requirements are relevant to the control of an aircraft on the runway after a critical engine failure?". If I had asked that question without qualification, someone would simply have quoted FAR 25.149(e) at me (actually, someone did anyway
). That's the only reason I mentioned Vmcg.
The consensus seems to be that with the exception of FAR 25.149(e), there are no relevant requirements, hence the need for a rapid reaction on the power or the very real threat of a departure.
If I am launching in a small twin under reasonably limiting conditions (weight/Hp/OAT) .. and one quits below blue line .. then I have a high confidence that my preferred option will be to miss the big trees during the subsequent crash landing ..
And I'm with you 100%. The point that I make on the thread SNS3Guppy cites is that it's that blue line speed that marks the threshold between an instant reaction of chopping the power and the possibility of taking the aircraft into the air. Vmca is not the threshold, nor is Vr.