Vernier Mixture and Throttle

[n2582d]

Personally, I would never exchange a friction lock for a vernier throttle. The friction lock type is cheaper. If you're thinking about changing it because your friction lock throttle creeps maybe you missed Service Letter 63-32:

SL 63-32.jpg

It's interesting that the FAA uses the term "acceptable data" rather than "approved data" in AC20-143 on the subject of replacing a friction lock type of control with a vernier style.

Friction Lock and Vernier Controls.jpg

That should just require a logbook entry with the acceptable data as it is considered a minor alteration.

[rydfly]

My '53 170B has a vernier throttle that was installed by the previous owner a few months before I bought the plane. He gave no explaination as to why he did it, but I suspect it had to do with the Bonanza he'd been spending a lot of time in that summer (I noticed it too had a vernier throttle setup). While it has taken some getting used to, now it's second nature and really a non-issue to operate.

That being said, it does seem a bit overkill when "fine" adjusting the throttle on my bird. Given the choice, I would have preferred it on the mixture knob instead of the throttle. In the end, it all works fine though.

[GAHorn]

...It's interesting that the FAA uses the term "acceptable data" rather than "approved data" in AC20-143 on the subject of replacing a friction lock type of control with a vernier style. That should just require a logbook entry with the acceptable data as it is considered a minor alteration.

That does not address "vernier" versus "non-vernier". That document addresses "rotatable" versus "non-rotatable" friction locks. There is a big difference. Some solid-wire controls using friction locks have knobs that freely rotate upon their shafts while others do not. Those are the types being discussed in AC20-143.

[n2582d]

Thanks for the correction George. I assumed that when they said, "controls capable of knob rotation at the instrument panel," they were referring to vernier controls.

[GAHorn]

Thanks for the correction George. I assumed that when they said, "controls capable of knob rotation at the instrument panel," they were referring to vernier controls.

I appreciate the inputs and references you are posting. Thank you.