Page 26 - Volume 10 Number 10

(Caution for the F90-series pilots: Realize that the entire range of trim settings the F90 has are “Up” settings. Zero trim is as far “Down” as it goes. Strange, but true. So you must take care to reset your normal takeoff trim setting after the exterior check is completed.)
There is one exception about setting zero trim for the visual check of the 350 or B300. Due to its longer fuselage, it was determined that neutral trim actually needed to be slightly nose down. Zero trim, therefore, has the trim tabs just slightly up, with their trailing edges higher than the trailing edge of the elevators. (Trim tab up ... elevator down ... nose down. Make sense?) Therefore, the 350’s procedure is to set the trim wheel indicator in the cockpit to a two degrees nose up (+2°) position before doing the exterior walk- around. Now the trailing edges should align perfectly.
I hope this article gives you a better understanding of this important preflight procedure ... why it’s there and how it is accomplished.
Fly safe!
Note: In the June issue of King Air, my friend and colleague Dean Benedict wrote a fine article about the Overspeed Governor’s Test Solenoid and its disconcerting tendency to stick in the test position. I’d like to add a comment about that.
Not many pilots realize that the speed at which the Overspeed Governor moves into the test setting is extremely different than the speed at which it resets back to normal. It comes down fast, but it resets back to normal very s-l-o-w-l-y. It’s never a good idea to have the propeller turning at a high speed when the test switch is activated. Man, it’s like someone did a forceful, sudden yank back on the prop lever! But the reverse is not true. When the test switch is released, the RPM just creeps back up. So I strongly suggest, and teach, that after you have done an OSG test, let go of the switch while power is still applied and watch for the creep up to begin before reducing power. Now you know with 100 percent certainty that the solenoid has not stuck. For what it’s worth, I also believe that the extra power and vibration of the higher RPM still existing when the switch is released makes it more difficult for the solenoid to remain activated/stuck.KA
King Air expert Tom Clements has been flying and instructing in King Airs for over 44 years, and is the author of “The King Air Book.” He is a Gold Seal CFI and has over 23,000 total hours with more than 15,000 in King Airs. For information on ordering his book, go to www.flightreview.net. Tom is actively mentoring the instructors at King Air Academy in Phoenix.
If you have a question you’d like Tom to answer, please send it to Editor Kim Blonigen at kblonigen @cox.net.
24 • KING AIR MAGAZINE
OCTOBER 2016