Page 29 - June 2022

in this emergency? First, reduce power as necessary to keep torque within limits. Second, remove power from the shorted switch by pulling the system circuit breaker (CB).
Now here’s where it gets interesting! There is only one CB that protects the circuit for both side’s SLPS system. That’s the good news: That you don’t have to find a left or right CB. The bad news is twofold. First, the CB is not labeled “SLPS” but instead is “Prop Gov Test.” You see, Beech uses this same CB to protect both the SLPS wiring as well as the circuit that allows the overspeed governor’s RPM to be reduced enough so that it may be tested. I wish the SLPS label were there by the CB also, but it’s not. The second piece of bad news is much worse: This CB is in the very worst possible position for the pilot to find it and pull it! Where? It’s the one farthest to the left on the second row down on the co-pilot’s right subpanel. In this position, it is totally hidden from the pilot’s view by the co-pilot’s control wheel shaft. Yes, it is easily pulled by stretching across the cockpit, reaching under the co-pilot’s wheel, and feeling for the leftmost CB. I strongly encourage any readers who are operating a King Air with this system to install a red plastic “pull cap” on that sucker to make it easier to find and pull!
A few paragraphs earlier I wrote: “Starting with serial number LJ-572, when an electro-optic SLPS trigger
replaced the mechanical switch, this cycling of the annunciator indeed occurs. Earlier airplanes, however, include a latching circuit and once the SLPS annunciator illuminates it remains on even as the valve loses and then receives power again. This is not good!”
The reason it is not good is because it allows the annunciator to sometimes illuminate when nothing is wrong. Unless the illumination is accompanied by the RPM decrease and torque increase, it merely is the result of some temporary “glitch” that activated the circuit erroneously. Moisture, perhaps? There is no need to find and pull the CB unless you experience the RPM decrease and torque increase.
If the SLPS were not removed when reverse thrust is desired, then we could never achieve reversing. As the power levers are moved through the Beta and Reverse ranges, moving the PLPS to smaller and then negative blade angles, the SLPS would prevent the blades from going flatter than 12°. The remedy to this predicament is to eliminate the SLPS whenever the power levers are lifted. Lifting is of course required to get behind Idle and into Beta and Reverse. Lift either power lever and both SLPSs disappear.
Here is a very common nuisance: The SLPS annunciators, one or both, illuminate and stay illuminated when the power levers are returned to
JUNE 2022
KING AIR MAGAZINE • 27