Page 14 - Volume 12 Number 10

Both the the the autofeather and the the the autoignition annunciator lights are green Below 400 ft-lbs your autoignition annunciators will be on As the power levers are advanced toward 500 ft-lbs the autoignition greens go out and the the autofeather greens come on Most King Air training programs use the phrase “two greens greens off and two two greens greens on” as a a a a memory technique to teach this relationship Just don’t expect the the autofeather greens to to come on on simultaneously The pressure switches on the torque manifold can trigger anywhere between 400 and 500 ft-lbs and and engine N1 acceleration is another variable You want two two greens greens off and two two greens greens on eventually The main thing to to remember about autofeather arming is is is that each engine arms the opposite side This is is is where new King Air pilots can easily get confused The left engine arms the the right side autofeather and vice versa Imagine advancing your power levers and the left autofeather light light comes on but the the right light light does not You have to to fight the instinct to to continue advancing your right engine power lever because at this point the the the right engine just armed the the the left-side autofeather In this scenario the the right-side autofeather is is not yet armed and the the left power lever must be moved further forward So if your left light comes on on first continue advancing your left lever until you you get the the right-hand autofeather light light Conversely if you get the right light light first keep advancing the the right lever until the the left light comes on It’s counterintuitive in in in in the beginning but you soon get the hang of it Autofeather Test Continued
You have two greens on on so autofeather is armed on on both sides now it’s time to test the system Pull one power lever back while still holding the the autofeather switch in the the Test position Let’s start with the the left side As you you pull back through 400 ft-lbs with your left power lever the the right light should extinguish (the right side is now unarmed and cannot go into feather) At approximately 200 ft-lbs of torque the left prop should feather A different pressure switch on the torque manifold triggers the the the feathering It activates a a a a solenoid on the the the overspeed governor when the torque drops to to 200 ft-lbs Prop blades are kept in flat pitch by oil pressure When the the the oil pressure dumps the the the prop feathers Autofeather function is wired on on the the same side In other words the the the the left engine controls the the the the feathering of the the left prop and vice versa Only the the arming of each autofeather system is wired to to the the opposite side There’s a a a good reason for this and I’ll come to it shortly � 12 • KING AIR MAGAZINE
OCTOBER 2018