Pete-
Your suggested methodology is pretty much the course I've been proceeding on my sim (James Price and I co-write our version of PMSystems, called Sim Control). I've been overhauling our hydraulics code and depleted hydraulic resources result in different deployment times of the flaps and gear on the 737, which I was hoping to model. The other malfuction I've been hoping to model is partial gear extentions and gear collapses, hoping that the physics of such a failure (air and ground physics) would be correct in FS, if there would be a way to hack the failure.
One application in particular is the standby hydraulic deployment of the flaps. With normal hydraulics, full flaps deployment takes around 37 seconds. With the standby system, the flaps deploy fully at around 140 seconds, +/- 30 seconds. This is where I was hoping to slowly ramp up the flaps offset to gradually deploy them over time. I found a flaps timing variable in the aircraft.cfg file, but I'm guessing those values are loaded when the aircraft loads, and thus cannot be dynamically modified.
BTW, thanks for adding the reverse failure. There is no backup system on the 737 for that!
Thanks,
Matt