S-TEC 50 is turning right

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volkerk

Filing Flight Plan
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Jul 19, 2023
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Volker
Dear all,

I have an S-Tec 50 installed and now the autopilot is always heading right in STB/HEAD-Mode. Any Ideas? Thanks a lot...
 
Do you have a mechanical HSI? Like a KI-525? If so, it is likely your HSI. It has a lamp and a sensor with a window on the heading bug that sends a signal to the AP to make sure you’re on heading. If the sensor or lamp is bad or dusty, it’ll keep hunting right.

I’m not home at the moment, but when I am, and if you think this is the problem, I’ll give you the contact info of who fixed mine. I got it back in less than 2 a weeks if I remember right.
 
Thanks. I have an electronic HSI, KFD 840 from Bendix/King, servo is running all the time to fully right...
 
My guess would be your turn coordinator or connections to the turn coordinator. The s-tec is a rate based autopilot and it uses the TC signals to sense if it’s turning, which way, and how fast. There are 3 wires that go between the TC and the AP. The tach signal, which tells the AP if the gyro is spun up or not (this one appears to be working, as you would never get the ready if it wasn’t), and then the roll signal and roll signal reference wires. An STEC dealer could plug in the test box and figure it out fairly quickly, but my guesss is the pickups in the TC are bad.
 
The plane came just out of annual...new battery was installed, new ELT - but nothing with the S-TEC 50
 
Hello Volker,

Please feel free to reach out to our support team at support@genesys-aerosystems.com and one of our techs can get some more information to assist you. Alternatively, if the issue was not present prior to the annual and only began after the work was done I would suggest reaching out to the shop that did the work. You can also find a list of S-TEC dealers in your area who can assist you with your issue on this link:

Dealer Locator | Genesys Aerosystems | Mineral Wells, TX

genesys-aerosystems.com genesys-aerosystems.com

Please let me know if I can be of any assistance. Thank you and have a great day!
 
Just an update. The S-TEC 50 computer has been checked by a dealer and is working perfectly. I tested another turn coordinator and encountered the same problem. The servos are working correctly, as verified by turning the S-TEC 50 right and left. I am using a KFD840 as the PFD...
 
When was the last time you had your plane rigged?
 
My HSI (KI-525 if I remember the model right) had an issue that commanded a continuous right turn when in heading mode. There is a light, window, and sensor in there that if the light or sensor is dirty or bad will not send the signal to the AP that the heading commanded by the heading bug has been achieved.
 
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