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Also, the 200 series moved the main buses from the cockpit pedestal to a location in the cabin aisle, just aft of the main spar. A neat panel is there under a clear plastic overlay painted with labels showing exactly what’s what. As in the past, two spare 325-amp isolation limiters are installed near the main buses to be available for on-the- road replacement.
The Five-Bus System
It might be said that the model 200 was a Super 100 since it had the same cabin size but offered a tremendous increase in overall performance. The Beech engineers were directed to create a similar change for the 90 series: To develop a Super 90 that would be head and shoulders above its C90 and E90 siblings.
Off to the drawing boards they went. Wow! It was 1978, and they had to modify what had been designed in 1963! What improvements they could make! Redo the nose profile to eliminate the “flat face” of the King Air and go with a sleek profile like that used on the Model 60 Duke. Use a wet-wing system and eliminate the bladder tanks. Go with a whole new wing, but use the landing gear from the 100 series to allow for a higher gross weight. Redesign the electrical system to make it more modern, copying a lot of what Boeing did on the 737. Use the T-tail, rudder boost system and cockpit layout of the 200 along with its automation of the fuel transfer
system. Lastly, use the 200’s stronger cabin door and dual-pane cabin windows to increase the pressurization differential. They called this model the F90.
Probably not many of my readers remember those days of the 1970s. The Carter presidency saw nearly runaway inflation and prices were soaring dramatically. After the Beechcraft financial analysts reviewed the changes that were planned, they concluded that this proposed F90 would need to cost more than its big brother, the 200, to account for these major changes that were to be paid for in late-1970s dollars! Oops that cannot be! So the engineers were sent back to the drawing boards with orders to tone it down and keep the price in line with reasonable expectations.
The pressurization increase, the T-tail, the 200-style cockpit layout, the automated fuel transfer, the landing gear from the 100 series and the 737-like electrical system were retained. The rest were tossed. So let’s talk about this new electrical system that first appeared on the F90 and continued in the C90A, C90B and C90GT and all its variants, and on the entire 300 series.
Although this article cannot go into the depth required to really “teach” this new system, I will say that one of the few similarities to the older system is the presence of left and right generator (main) buses. Instead of subpanel buses, we now have a triple-fed bus, a center bus and, as before, a hot battery bus—five buses in total, with
26 • KING AIR MAGAZINE
OCTOBER 2024