PT6 FCU during start
I've read references that say during startup the fuel metering valve will be at the low flow stop, but I don't see how that can be since Ng will be well underspeed which should drive to max flow. I thought it might be a special case when Px and Py are near ambient, but that doesn't make too much sense because the pressure reference they are working against isn't ambient, it's the low vacuum in the acceleration bellows, and I don't see any indication of springs that might explain a different result at low pressures. What am I missing?