Page 24 - Volume 15 Number 12

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in acceleration rates your two engines happen to be, the power being produced will remain low enough that no significant asymmetrical thrust can be achieved. (Realize that 73% N1 is much, much less than 73% power.) But by the time three seconds have elapsed, both engines will be stable at this elevated N1 speed, meaning that the response rate of the engine to power lever movement will now be virtually instantaneous, with no spool-up lag. Torque and ITT will increase right in sync with power lever motion and the desired values can be reached without overshoots.
Back in the 1970s I was using the GI Bill to pay for my Learjet type rating through FlightSafety International in Wichita, Kansas. The airplane I actually flew was a model 25C equipped with the CJ610 straight jet engines. It was there that I was first taught about “throttle slams.” Recovering from an imminent stall at idle power, we were taught to slam the thrust levers forward to the stops, then pull them back one-half inch. Like magic, this worked exceedingly well, yielding a high but not excessive power in a short time period. Although it was common that one engine accelerated much faster than the other, the resultant asymmetry never seemed excessive due to the fuselage-mounted engine location.
Trying this same technique on King Airs – going forward to the stops and back a half-inch – always kept torque and ITT within limits but when the two engines had very different acceleration rates the yaw tendency was rather fierce, since the engines were mounted outboard on the wings. That’s why the one- third forward bump, the slight delay, and then the rapid run to the desired power works much more successfully.
As stated at the start, you may well never need to use this technique. But practice it a time or two when you next fly your King Air – not necessarily in a stall recovery or balked landing situation, but just “playing” with the power levers, starting with them at idle – and see what results. You can even do it with the brakes locked when beginning a takeoff roll on a longer runway. I suggest you release the brakes and start rolling after the post-bump, three-second delay.
I think you will want to add this Bump and Run arrow to your quiver of operating techniques. KA
King Air expert Tom Clements has been flying and instructing in King Airs for over 46 years and is the author of “The King Air Book” and “The King Air Book II.” 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 books, 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 editor@blonigen.net.
22 • KING AIR MAGAZINE
DECEMBER 2021