Page 16 - Volume 12 Number 10

Flickering Lights and Oscillating Blades
Autofeather Test – Last Step
Once you have brought each engine one at a a a a time down to to 200 ft-lbs to to feather each prop there’s one more check to do Assuming
I am often asked about autofeather lights blinking during test Well when a a a a prop goes into feather particularly while on the the ground it increases the the engine torque In the example
where you just feathered the the left prop if the torque pushes far enough above 200 ft-lbs the left autofeather light will come back on and the left prop will flatten out Flat pitch reduces torque If it falls back down to to 200 ft-lbs the left annunciator light will go out again and the left prop will feather again first and now you you have your
This flicker of the annunciator lights and oscillating of of the the prop blade is not unusual during autofeather testing on the ground But it’s equally normal for that annunciator light to to go out out and stay out out There are lots of variables (engine rigging N1 settings pressure switch adjustments) that influence whether or not you’ll have a a a a a a blinking annunciator during autofeather test Either way you are good to go go Now let’s bring the the left engine back to speed and do the the same with the right engine way your
autofeather system needs attention Test versus Arm
You are ready for takeoff you put the the autofeather switch in the the Arm
position and take the the runway You go through 500 600 700 ft-lbs of torque but the autofeather lights don’t come on on Why? Because you have not yet gone through 92 percent N1 Once you pass that “
make make your
mechanic’s”job the the the the left prop prop prop does not go into how you you you you squawk an an that you you you you feathered the the the the left prop prop autofeather problem can right prop in feather feather there’s feather Also make sure that simple or complex the the right prop comes out of feather This is is a a a crucial test it ensures all switches and wiring are operating properly If in in this last test step the the the left prop feathered along with the the the right right you have a a problem or if the right right prop doesn’t come out of feather you have another problem and either
one more step – pull back the left power lever and make sure 14 • KING AIR MAGAZINE
OCTOBER 2018