A Device Mystery

A device mystery, solved, with our good friend, Dean Showalter.  Enjoy reading:

PART 1:  The Mystery…

Good morning friends!

I have a puzzler for you today… last Saturday, I was out on the ramp at our airport, and I saw this A-35 Bonanza with a device on the left wing, and I wasn’t sure what it is. Here’s a photo:

Wing Warning Switch

I have a guess, but I’d like to hear your guesses.

Hit reply and tell me what you think this is… I’m confident we can figure it out together!

Thanks for joining me in the process of continuous learning!

Have a great Saturday,

Dean Showalter

PART 2: Mystery solved!

Hi Friends,

In my last email, I was asking for feedback on what you thought about the strange device I’d seen on a Bonanza’s left wing recently… well, here’s the answer, in the words of my good friend, Aram Basmadjian:

“That is the stall warning vane commonly found on the early Bonanzas.”

Thanks Aram!

He even provided a screen shot of one he saw for sale:

Warning Switch

Notice it’s 14 volt… Aram later told me it’s connected to a stall warning horn.

Now I know yet another detail about the amazing Bonanza’s 🙂

Thanks so much to all of you who responded with thoughts about what this gizmo was. Most of the responses were right on target, having something to do with stall warning and AOA detectors.

Norman also got it right, when he said, “Double vaned, stall warning device. Made me look it up Dean. I hope I’m right!” Yep… you were right Norman!

Some other guesses were:

    • Maybe Hobbs airflow switch?
    • A manual gear indicator?
    • Wing root vortex generator to prevent airflow stalling at low speeds. (This person later changed his guess to a stall warning device.)
    • No clue unless it is a mechanical cricket used for signaling a left turn.
    • How about a mechanical down and locked indicator?Gear position indicator?

I always enjoy learning new things about airplanes, and this one was especially interesting.

Thanks for joining the adventure!

Dean Showalter


If you enjoyed Dean’s articles you can find more on his website at:  http://airplaneownermaintenance.com/

THIS is Why we do Annual Inspections

THIS is Why we do Annual Inspections, an article by Dean Showalter:

Good morning aviators and friends!

I’ve got a good one for you this week… check out this picture, and be as surprised as I was when I found it last Monday 🙂

Yep, that trim cable pulley is broken. And yep, the cable is sawing into the bushing… after removing the pulley and bushing, I discovered the cable had worn a groove completely through the bushing and was even cutting into the bolt inside the bushing.

Here’s how I found this broken pulley:

It’s a Piper Cherokee Six… a really nice one, actually.

Imagine I’m standing on the right side of the tail, in front of the stabilator.

There’s a small inspection panel on the side of the tail… the ELT is mounted just inside.

The hole is just big enough for me to reach my arm inside.

When I inspect these Pipers, one thing I like to do is reach my arm inside this access hole, up and slightly forward to the two trim cable pulleys in the picture above, and make sure I can rotate them with my fingers. And that’s what I was doing with this airplane.

Most of the time, the pulleys rotate easily, and everything is fine.

Not this time.

This time, my fingers were “seeing” something out of the ordinary.

In fact, of all the many Pipers I’ve ever inspected, this was the strangest thing I’ve ever seen in this particular location.

The question is, how did this happen?

I’ve been trying once again, to be an “airplane detective,” and figure that out.

Did the pulley stop rotating, and the cable cut into it over a long period of time?


But I don’t think that was the whole story, and here’s why:

When I turned the trim system to one extreme of its travel, the right cable turnbuckle was about a foot away from the pulley.

But when I turned the trim system to the opposite extreme of its travel, the left turnbuckle moved right up against the pulley bracket.

I think perhaps this contributed to breaking the pulley.

Something was not correct with the stabilator trim system rigging.

So in this case, it will be important to not only install a new pulley, a new bushing, and a new bolt, but to also rig the trim system according to the maintenance manual instructions.

And when that is accomplished, I don’t think that pulley will ever break again.

Sometimes, annual inspections can feel redundant, and we might occasionally wonder if it’s worth it.

I just want to say, “It’s totally worth it!”

Your precious cargo (your family and friends) are counting on you for a safe flying experience… and annual inspections are one of the best ways to catch potential issues before they create an in-flight problem.

Have a great week friends!

Dean Showalter

P.S. You might wonder, will that trim cable need to be replaced?

Amazingly, I don’t think so… I examined it closely, and did not find even one broken wire strand… (if I found even one broken strand, I’d replace it, but the cable appears to be in good condition.)

If you’d like to read more of Dean’s articles and listen to his educational Podcasts, visit:  http://airplaneownermaintenance.com/

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