S-TEC 30 Turn Coordinator Knob

[DesertNomad]

I have an S-TEC 30 that my shop moved one slot to the right to make room for a new engine monitor. In the process, the knob on the top left came loose and they did a temp fix to it by putting a small screw through the knob to friction-hold it to the shaft.

They said they will replace it but are calling other shops about the part rather than just calling S-TEC (Genesys) as my shop really does not do avionics (and is not an S-TEC dealer). Any idea what this will cost from Genesys? I think someone mentioned this sort of repair here before.

Another shop is going to install my new engine monitor (since I have all but given up on my local shop) and metal panel. I am thinking of getting the pert from S-TEC myself and just billing my original shop.

Really not happy that I can't find a good local shop in Reno. My favorite shop is 400 miles away near Portland, OR but the weather there and distance makes it very inconvenient.

 

[James331]

I had the elbow universal joint go bad on mine, common problem, it was a field repair and under $100 as I recall.


From my old post


Totally forgot to mention the price to fix the stec

PARTS: 68.24
LABOR: 94.80
TOTAL: 163.04

 

[DesertNomad]

Did you get the parts directly from S-TEC?

 

[Stan Cooper]

I found this nearly year old thread while searching for S-TEC 30 U-joint failures, and thought my experience might be helpful.

I installed an S-TEC 30 in my 172 in 2004, and it has been extremely reliable. Flying back from Palm Springs in early July, my turn knob/mode switch failed; the shaft slid in and out without doing anything. I pulled the unit out of the panel and heard something rattling inside, so I removed the case and both the universal joint plastic cups that connect the serrated shafts had split and come loose inside the case. I called Genesys to order a replacement and was told I had to order it through a dealer. The Genesys website has a dealer locator (type in your ZIP code and it spits out the contact info for dealers within the specified mileage of your location), so I called a dealer 30 miles away and he said the u-joint is a common failure and offered to fix it, but said if I was 'handy' I could repair it myself by using shrink tubing over the cups. I took his suggestion, and it worked like a charm. Cost=four short pieces of shrink tubing (I applied two pieces to each cup, shrinking one piece then a second piece over the first on each cup). I'd post pictures, but need 5 posts to include image links.

EDIT - Five posts; photos added.

-Stan

 

[James331]

Or you could get the proper part for $68.

 

[Stan Cooper]

Or you could get the proper part for $68.

Yes; I could have ordered it, paid the $68 plus shipping, waited for it to get here, installed it and have it fail again.

The owner of the avionics shop that explained the shrink tubing fix claimed that by using shrink tubing, there's enough 'give' that the repair will last as long as the airplane does. He said the failure of the plastic was due to different coefficients of expansion between the steel shafts and the plastic with temperature changes, and that over time the stresses would inevitably result in another failure. YMMV.

Photos added to post above.

 

[James331]

My mileage did vary, mine lasted nearly a decade, it's your plane and your life and your ticket, but I wouldn't fly in a airplane that was shade tree mechaniced like that, especially if this plane is used for single pilot IMC, I'd also not use a avionics shop that recommended that "fix".

 

[eman1200]

welcome to PoA, Stan.

 

[bnt83]

Clearly a crapy design, may even be worthy of an AD.

 

[Stan Cooper]

Uh, it was cracked plastic caused by a defective mechanical design. The shrink tubing "shade tree" fix will last the life of the airplane.

Thirteen years ago, I upgraded the panel with new avionics, redid the interior, and replaced the six tired TCM piston/cylinder assemblies with new ECi Titan cylinders. I did all of the work including the avionics integration design and testing myself under the supervision of my A&P I/A and the local FSDO inspector. I did pay to have it professionally painted. 900 hours later, it's been a damn near perfect airplane with very few issues (including the failed u-joint in the S-TEC 30). For anyone interested, a PowerPoint presentation on the project is on the PDF Archive site at https://www.pdf-archive.com/2015/08/01/n2686u-project-0405/.

I take aircraft maintenance very seriously. Thanks for indulging my little rant.

The original panel when purchased in 1999

The updated panel completed in 2005:

 

[mtuomi]

There's an old saying, "Some people do what they can. Some people do what they want". You obviously do what you want. That's very impressive work!

 

[455 Bravo Uniform]

Nice!