lifendet Posted April 7, 2018 Report Share Posted April 7, 2018 Having trouble with my Stec 55x Autopilot in my J. Havent done any trouble shooting but all ideas are considered helpful. When in nav gpss mode or nav alone it doesnt follow my Gps flight plan anymore. It just wonders off on its own and also when I select Hdg it doesnt follow my bug either. In Alt and Vs mode it works but thats it. On start up the internal check shows no faults but it might be checking the control face itself and not the servos or maybe its just a electrical check to everything. Any ideas? Hoping my roll servo is not the fault.. Quote Link to comment Share on other sites More sharing options...
PaulM Posted April 7, 2018 Report Share Posted April 7, 2018 Have you run through the POH pre-flight checks and the maintenance manual checks?http://www.gvm.ch/documents/avions/pa32/sys55Xpoh.pdfhttp://www.aeroelectric.com/Installation_Data/S-Tec/S-TecServiceManual.pdf I would suspect a bad roll servo.. since all horizontal modes are bad. But it could be your turn coordinator signal as well. With the standard test tools listed in the service manual a tech should be able to isolate it quickly. The tests in the manual (HDG hard left and right) with no yoke movement will probably be the servo. Also, when activated does it restrict the yoke?.. or no friction?.. No friction is definitely the servo. 1 Quote Link to comment Share on other sites More sharing options...
Marauder Posted April 7, 2018 Report Share Posted April 7, 2018 Having trouble with my Stec 55x Autopilot in my J. Havent done any trouble shooting but all ideas are considered helpful. When in nav gpss mode or nav alone it doesnt follow my Gps flight plan anymore. It just wonders off on its own and also when I select Hdg it doesnt follow my bug either. In Alt and Vs mode it works but thats it. On start up the internal check shows no faults but it might be checking the control face itself and not the servos or maybe its just a electrical check to everything. Any ideas? Hoping my roll servo is not the fault.. What’s providing the GPSS signal? Sent from my iPhone using Tapatalk Pro Quote Link to comment Share on other sites More sharing options...
lifendet Posted April 7, 2018 Author Report Share Posted April 7, 2018 4 minutes ago, Marauder said: What’s providing the GPSS signal? Sent from my iPhone using Tapatalk Pro The gpss signal is direct from the 55x.. Quote Link to comment Share on other sites More sharing options...
lifendet Posted April 7, 2018 Author Report Share Posted April 7, 2018 10 minutes ago, PaulM said: Have you run through the POH pre-flight checks and the maintenance manual checks?http://www.gvm.ch/documents/avions/pa32/sys55Xpoh.pdfhttp://www.aeroelectric.com/Installation_Data/S-Tec/S-TecServiceManual.pdf I would suspect a bad roll servo.. since all horizontal modes are bad. But it could be your turn coordinator signal as well. With the standard test tools listed in the service manual a tech should be able to isolate it quickly. The tests in the manual (HDG hard left and right) with no yoke movement will probably be the servo. Also, when activated does it restrict the yoke?.. or no friction?.. No friction is definitely the servo. When activated, once I notice it's not following my GPS I am able to use the yoke and control the Aircraft without disabling the modes or Autopilot. No friction whatsoever or fight against it. Quote Link to comment Share on other sites More sharing options...
Cruiser Posted April 7, 2018 Report Share Posted April 7, 2018 will it intercept and track a VOR signal ? Quote Link to comment Share on other sites More sharing options...
PaulM Posted April 7, 2018 Report Share Posted April 7, 2018 33 minutes ago, lifendet said: When activated, once I notice it's not following my GPS I am able to use the yoke and control the Aircraft without disabling the modes or Autopilot. No friction whatsoever or fight against it. In roll and pitch?... Well if there is no friction and no difference if you hit the A/P disconnect then I'm going to say servo. It isn't clear if there is friction in the beginning, and it works for a while... then once you notice that it isn't tracking there is no longer friction. Run though the test sequences.. see what works and what doesn't. the GPSS signal would come from the GPS NAV... 430? 530?.. anyway since it doesn't work in all 3 horizontal modes I doubt it is the inputs.. but the outputs. 1 Quote Link to comment Share on other sites More sharing options...
sgrooves Posted April 7, 2018 Report Share Posted April 7, 2018 Had a similar issue with my Stec55x. Turned out to be the ACU driving the Stec from my Aspen unit was bad. The ACU was replaced under warranty, labor wasn't cheap though. Quote Link to comment Share on other sites More sharing options...
Mooney in Oz Posted April 8, 2018 Report Share Posted April 8, 2018 Had this happen to me too a couple of years ago. It turned out the roll servo over time had somehow loosened and come off it's mount in the left wing. Quote Link to comment Share on other sites More sharing options...
mike_elliott Posted April 8, 2018 Report Share Posted April 8, 2018 6 hours ago, Mooney in Oz said: Had this happen to me too a couple of years ago. It turned out the roll servo over time had somehow loosened and come off it's mount in the left wing. That thing is a B*tch to R&R, very likely someone "neglected" to install the B*tch bolt. 1 Quote Link to comment Share on other sites More sharing options...
thinwing Posted April 10, 2018 Report Share Posted April 10, 2018 That's why I love BK servos...the moter portion unbolts with two 7/16 bolts leaving capstan still in place... Quote Link to comment Share on other sites More sharing options...
lifendet Posted April 12, 2018 Author Report Share Posted April 12, 2018 Had some time today to figure out the problem. Opened the underwing panel and found the connector for the roll servo disconnected. Guessing some ruff turbulence shook it apart. Glad I took a look instead of having a Technician charge me.. 2 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.