The International Cessna 170 Association

My instrument panel in the 170B has a hole about 3/4" in diameter
below the center instrument. Can somebody tell me what that
hole was originally for? Thanks!

Jim,
Your first post said that you had a 1950 170A. Did you trade that in for a newer 170B? I'm guessing what you are looking at is the hole for the knob on the horizontal directional gyro. See figure 76.

What year is your plane? There are differences in the panels by year. If it's slightly below a 3" instrument right in the center of the panel below the glare shield, it's probably the hole for the adjustment knob of an AN DG that was originally in the 3" hole above it. I still have the AN DG in my plane, and that's where the knob is (in a separate hole).

Edit: I see Gary beat me to it. We must have been posting at the same time.

I've got a '50A and a '52B. Getting ready to sell the A. I think they both have that hole.
Apparently it was for an adjustment knob for the DG - thanks.

I have a 1958 C-180A with that same hole. Still have the AN DG that came out of it from the factory that still worked, although it sounded like a coffee grinder.

I've found a use for that empty hole. I'm going to fill it
with a picture of Lauren Graham, star of The Gilmore Girls.

Possibly a 1" dia vac gauge could be installed in the hole, or an iPad USB power source.

Or a button plug:

George- I remember you used to call them Wilkie buttons.

hilltop170 wrote:George- I remember you used to call them Wilkie buttons.

Yep...that's what the old timers called them and the term became synonymous. You've got a scary memory.

gahorn wrote:

hilltop170 wrote:George- I remember you used to call them Wilkie buttons.

Yep...that's what the old timers called them and the term became synonymous. You've got a scary memory.

wilkiebutton.jpg

I never knew them by any other name! I used to tell my students that's what they were called, too.