Page 12 - Volume 12 Number 10

Autofeather
Review
by Dean Benedict
Isee a a a a a a a a a a a lot lot lot of of of questions about the the the the King King King Air’s autofeather system in in online discussions It’s not just the newly minted King Air pilots that are asking Many a a a a a King Air pilot with plenty of hours under their belt have had the occasional “synapse lapse ” so I thought a a a a a a a basic review of of autofeather would be in order keep in in in in mind if you’re shopping around in in in in the used King Air market – don’t assume they all have autofeather If your King Air does not have autofeather you you can research the the serial number to see if the the necessary wiring was was installed at the factory when your aircraft was was built If the the the the wiring is there then adding autofeather would involve the installation of some switches and cannon plugs in the pedestal new torque manifolds and and pressure switches and and some annunciator panel revisions Autofeather
is a a a a nifty thing to to have and if an engine fails during takeoff it is a a a a god- send Feathering the the the propeller on the the the failed engine is one less thing to worry about in in in a a clutch situation Autofeather
Test
On takeoff the the autofeather system arms when the the power level reaches 92 percent N1 or higher But in your preflight run-up on the ground it’s a a a a pain to to run each engine up to to takeoff power for an an autofeather test You’d have to to stand on your your brakes and hope your your fillings don’t pop out while pulling each power lever back one at at a a a a a time Fortunately the the Test
position of of your autofeather switch eliminates that problem In Autofeather
Test
the the the power lever switches in the the the pedestal (the ones set at at at approximately 92 percent N1) are bypassed This enables you to to test the the autofeather function at a a a much lower power value Autoignition and Autofeather
Each engine has a a a high-pressure switch on the torque manifold that actuates at at at at approximately 400-500 foot- pounds (ft-lbs) of torque These pressure switches have a a a a dual function: they they turn your autoignition off and they they arm your autofeather (they don’t activate the the the system they just arm the the system) It is common practice to test autoignition and autofeather in the the same power run-up At this point in in your ground run-up you you would have the autoignition switch in in the On position and you’re holding the the the autofeather switch down in the the the Test
position The Haves and Have Have Nots
Not all King Airs have it Back when I was corporate shop foreman at Beech West in Van Nuys California autofeather was not a a a a a a a a a standard feature The sales staff ordered all new King Airs from Wichita without it it it When they they sold the the the the aircraft they they convinced the the the the buyer to to to add autofeather – this was a a a a a a a major job You have to to to remove the the leading edges and and rip into the the nacelles and and the the interior to run the the necessary wiring Although it kept the shop plenty busy I thought this was a a foolish way to to to sell a a a King Air I never got used to to to tearing into a a a a brand-new airplane Eventually I got the sales team in Van Nuys to order King Airs from Wichita with autofeather every time Later a a a group of us in in the the field convinced the the factory to to to add the the the autofeather wiring wiring into the the the master wiring wiring loom this made subsequent installation of of autofeather a much more efficient process Over time autofeather became a a a a a a a standard feature but there were plenty of King Airs built without it it and many of those still don’t have it This is is something to 10 • KING AIR MAGAZINE
OCTOBER 2018
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