I haven’t had a lot of success with Chiffon cakes…the always seem to fall out of the pan…I think I underbake slightly.
Bill, this one did fall out of the pan, but since it was resting upside down on a rack it only fell a fraction of an inch and was still usable. I don’t think this one fell because of underbaking, it was 190F internal temp when I took it out and probably rose a little higher than that (I took the thermometer out as soon as the numbers slowed down, not when they stopped). Chiffon does flatten slightly in the oven at the point when it’s fully baked.
I do think this one fell because of the non-stick pan, as it had pulled away almost completely intact. When they fall out of the pan and are broken in pieces, with plenty still left sticking to the pan, that’s when I would suspect underbaking, as the structure isn’t set enough to hold it together during the cooling/shrinking period.