Originally Posted by
wrench1
We're talking about the same topic just opposite ends of the spectrum. A couple more tidbits. Keep in mind this droop is nothing more than a "feature" of an analog-controlled governing system. In digitally-controlled governing systems droop is basically non-existent even on the same core engines. But from my understanding there are a few other items that determine the inherent droop other than spring strength in an analog system. There is also the possibility of positive "droop" which I've seen called "droop cancelling"(?).
Now in some other older droop designs they also added an "anticipator" or "bias" device that "anticipated" the droop and reduced its effect (value). While the "non-linear" side of your statement is at or beyond my skill set, I seem to recall this type of governing system had to be developed in some form of non-linear fashion in order to function throughout its control range due to the variables of the signal inputs/outputs. Its my understanding that a digital controlled governing system is more linear due to the fact the input/output signals can be processed almost instantaneously via the EECU or similar unit and acted upon.
Having been riding shotgun in a 206 when it had a high side governor failure in a difficult location you will appreciate what that GOV does. Lucky for me, the pilot had a light touch and we made it down without me having to change the engine that night. If I can get it to post, I'll put up a booklet put out by Bendix/Allied Signal on your GOV/FCU system for your reading pleasure. Good luck.
Thanks wrench, I appreciate the info. I think I already have the Bendix manual. Sadly, because I'm new to the forum, I can't post urls or images, but the document I have has a cover page with teal and white background. The title is "Operation and Service Manual - Model DP-T3 TURBINE ENGINE MAIN FUEL CONTROL". If you have a different one, I would love to have a look
And indeed the manual shows the anticipator (aka droop compensator) which allows collective position to turn a biasing cam in the governor. Such a cool document!
Thinking of the governor taking a nap gives me sweaty palms, glad you made it out!
John