The International Cessna^® 170 Association

Has anyone had experience drilling a hole in the control wheel for a mike button. My mechanic says it would compromise the integrity of the metal and lead to cracks. We were talking about a 3/8 hole to stick a button switch in.

It CAN be done but MAY NOT be done.

You'd have to get approval for the modification if you wanted it to be legal.

(Legality aside), if you were to make a hole in your yoke, I'd make it as small as possible. Like two little #6 screws to hold a little bracket that has the PTT button. Then, Neatly wrap the yoke with leather and state that the bracket is epoxied onto the yoke with no holes. (Not that anyone has ever done that before)

In the end, it's a whole lot of work for something that's easily solved with a piece of velcro

My god! Another boolegged mod that I didn' even realize I'd done. I had a set of "Rams Horn "control wheels that came out of some sort of a later model Cessna and I drilled them for the installation of a PTT button switch and wiring. They were plastic, not metal. Made a really neat looking job and worked fine.
I'm going to have trouble sleeping tonight.

To save any question whatsoever, I simply used a couple of adel clamps, fabricated a mount bracket, and screwed it all together. I can give more details on the clamps I used if anyone would like. No question of legality, no question of any supposed loss of integrity, and easily removable should someone want something different in the future.

Structurally altering the control yoke requires approval.

Telex makes a simple solution:

There are lots of ways to mount PPT switches but I prefer not to drill any holes or use any type of metallic clamping which could scratch the yoke. It's not too clear in the picture but a standard Telex PTT with the velcro strap can be wrapped around the hub of the yoke and velcro-ed with the button pointing down. It's very natural to hold the yoke at the hub and reach under the hub and push up on the PTT button. It does not create any pinch points or snags and is out of the way when not in use and really not visible unless you're looking for it.

Click on picture to enlarge.

This location works well for me. The switch was installed there by my avionics shop; apparently they were not concerned about structural integrity.

John.....if you roll that thing back right side up you'll get a lot further transmit range (assuming your
antenna is on the roof.

George, The yoke is the correct way. Dad and me with long legs turned his long ago....Haven't had any problems with transmitting.....

Ill post a photo of the solution. We used a clamp, small push button switch with a detent you can feel when you push it in, and a clamp with two 6/32 screws. My question is what defines the requirement for an approval for a modification and who approces it. And what is an AP allow to do.

Brad, with the steering wheel set like that when you send a position report, the flight service guy will have to stand on his/her head to understand it.

vcavu wrote:Ill post a photo of the solution. We used a clamp, small push button switch with a detent you can feel when you push it in, and a clamp with two 6/32 screws. My question is what defines the requirement for an approval for a modification and who approces it. And what is an AP allow to do.

FAR 43 describes those operations which are major and minor alterations.
Drilling a hole thru your yoke is a structural alteration. Structural alterations are major alterations.
Major alterations require a Form 337, signed by an A&P with Inspection Authority (IA). It is then submitted to FAA for approval, (Field Approval) which require supporting engineering or previously approved data.

Your A&P can sign off "minor" alterations and repairs only.

Owner/Pilots may sign off "preventive maintenance" as described in FAR 43, Appdx A.

johneeb wrote:

PTT switch.jpg

This location works well for me. The switch was installed there by my avionics shop; apparently they were not concerned about structural integrity.

Didn't see the PTT, But love that you also turned your yokes upside down....Dad and I are long legged, So years ago we also turned our yokes your way!

I'm 6'1 and have no problems with the yokes. How close do you bring your seat?