It is not a typo, but it is a mistake. Shutting off the avionics was a good idea back in the 1950s shortly after transistors were first invented. The voltage sag during engine cranking destroyed those early transistors. Modern transistors and avionics have no such vulnerability. But the advice to shut off avionics during engine start keeps being passed on from instructor to student because that is what they were always taught. I do not know of any avionics manufacturer that recommends shutting off their units prior to engine start. If you find one, please post the name of the manual and page number. And do not buy their inferior products. I have started my engine hundreds of times, always with the avionics turned on, except once when my biennial-flight-review instructor told me to turn it off. I have since removed the avionics switch from my RV-12. It is an unnecessary single point of failure. By the way, there is no such thing as a voltage spike while engine cranking. It is a voltage sag.
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