Page 22 - Volume 11 Number 12

left engine’s power was increased. With more power on the left, the nose wheel deflected to the right as the plane slipped forward and turned away from the powered-up engine. Which rudder pedal went forward? The right one, of course. The pilot said, “There is the Rudder Boost activation,” without realizing that it was backwards! “Good foot; good engine.” The left, not right, pedal should have gone forward ... as it did when we released the brake, taxied forward to center the nose wheel, then applied the parking brake HARD and repeated the test.
I wrote earlier that there were differences in the King Air braking system depending upon model and year. If you have learned and know your exact particulars, great. But if you are unsure, or are flying a variety of King Airs, then a dangerous “gotcha” can be discovered accidentally. You see, in many King Airs the copilot’s rudder pedals cannot operate the parking brake! In these models, “Shuttle Valves” separate the pilot and copilot sides and the check valve exits only in the pilot’s lines. If the copilot is flying the leg, taxis up to the parking area, and asks the captain to pull the parking brake knob for him since he cannot reach it, the brake is not set! Only if the copilot releases his pressure, the captain takes over and applies the pressure, can the parking brake be utilized. As stated, this is not true for all King Airs, but it is safer to assume it is the situation than to think the brake is set when actually it may not be.
Finally, how about releasing the parking brake after it has been set? Please – after the chocks are in place – take the time to sit in the pilot’s seat, apply force on the top of the rudder pedals, then push the knob in to release the brake. If the knob is pushed in when pedal force is not present, three “bad” things can happen. First, because the trapped high pressure on the downstream side of the check valve is not balanced by high pressure on the upstream side, it is physically more difficult for the cable to push against that pressure to release the check valve. Second, balancing the pressures prevents a sudden surge of high pressure liquid – a shock wave – that will travel upstream to the master cylinders and increase their propensity to develop leaks. Third, it is safer. By holding the brakes, the airplane won’t roll even if the chocks are not yet in place.
Trust the parking brake totally? Never! Use it often? Always! 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, contact Tom direct at twcaz@msn.com. 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.
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20 • KING AIR MAGAZINE
DECEMBER 2017