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Lever Lock Switches
... and a Few That Look Like They Are, But Aren’t
by Tom Clements
When I taught King Air ground school at Beech Aircraft Corporation back in the 1970s a name we used often was “lever lock switch.” In preparation for this article, I went to my dictionary to see if this word actually existed and was not too surprised to find that it did not. Instead, what I found was “toggle switch” and “locking lever.” The definition of toggle switch found is: “An electric switch with a spring to open or close the circuit when a projecting lever is pushed through a small arc.” The “locking lever” addition means that the lever cannot be moved until it is unlocked and this means that it must be pulled before it can be moved up or down or left or right. For the purposes of this article I think I will revert to the old familiar “lever lock switch” that I presume is familiar to most of my readers.
Perhaps the most common example of this type of switch in almost all King Airs is the left or right bleed air switch. If the copilot were to brush his hand against this switch accidentally as he reached for an iPad, there’d be no chance for a sudden loss of bleed air since no matter how hard he hit the switch it would not move if he had not first pulled it toward him, typically using the combination of his or her forefinger and thumb.
As years have passed, more lever lock switches appeared in King Air cockpits. The first three 90-models – 65-90, A90, and B90 – had none. Bleed air lever lock switches made their appearance on the 100 model when it premiered in 1969. But not until the appearance of the 200 model in 1974 did more lever lock switches join the cockpit controls. There is an interesting story about what prompted the appearance of two of them: the left and right “ignition” and “engine start” switches.
22 • KING AIR MAGAZINE
As you likely know, the model 200 incorporated many, many changes and improvements over its predecessors. One of these changes was the relocation of the parking brake’s control knob from its previous spot (the highest left corner of the pilot’s left subpanel) to the new one that was now the farthest left portion just below the left subpanel, where the pilot’s air valve knob previously resided. Not too surprisingly, some 200s in the first few years blew all four tires on landing. It was obvious to see why: The pilot thought he was shutting off the conditioned air flowing down toward his feet but what he actually accomplished was pulling on the parking brake: mistake!
Another change was relocating the pilot’s air valve knob to the left and slightly below where the pilot’s control wheel’s shaft exits from the subpanel and also changing how the knob functioned. Now the air flowing
FEBRUARY 2023