tigers2007 Posted September 1, 2017 Report Share Posted September 1, 2017 I had this issue prior to my avionics upgrade but they: disconnected the A/P motor linkage and had the motors cycle several times around and around, cleaned the connections with Deoxit, and made a new harness. Everything worked just fine until yesterday's flight back home where it started to do what it did before. If I set the heading on the heading indicator to my current heading, it will roll hard to the left, then to the right and then to the left like it's drunk. Any idea how to sober this thing up? I'm thinking two new G5's could rule things out... Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
OR75 Posted September 1, 2017 Report Share Posted September 1, 2017 What does it do when you just engage the autopilot but NOT the nav coupler ( when you try to turn left or right with that middle knob in the console) ? Quote Link to comment Share on other sites More sharing options...
tigers2007 Posted September 2, 2017 Author Report Share Posted September 2, 2017 The roll knob works I suppose; if I turn it to the opposite direction it will change the roll to that direction but it will not stabilize if I put the knob back in the middle. It just seems to want to remain in a maximum turn. Note that it isn't trying to do a barrel roll - it just wants to turn 15 degrees one way. Maybe the connection to or within the AI is kaput? I suppose I could just throw in a G5 AI for now and see if that results in a win-win. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
OR75 Posted September 2, 2017 Report Share Posted September 2, 2017 You should be able to use the roll knob exactly like a yoke. From what you wrote above I am not sure if you can or not Quote Link to comment Share on other sites More sharing options...
INA201 Posted September 3, 2017 Report Share Posted September 3, 2017 We went through mine for rocking back and forth and basically ended up sending all the components off to Bevan Rabell and having it all rebuilt. As I understand it is that the rocking part was caused by the motor having too much resistance. I don't remember the voltage that was required but just for an example let's say normally it should require like 1.3 volts but mine was taking let's say 2.5 volts or more. We sent the motor off and that fixed it. A pro can at least test the resistance for the proper voltage and at least eliminate that issue. They just hooked the motor up and slowly dialed up the voltage until the servo actuated to determine what it took. Anyway, I hope yours is that simple. 1 Quote Link to comment Share on other sites More sharing options...
jetdriven Posted September 3, 2017 Report Share Posted September 3, 2017 Wing rocking is often caused by a sensitivity adjustment or a Roll servo Startup voltage too high. If it is ignoring the heading altogether then it's something more serious than that. If the Roll knob works correctly then it's more of something to do with the attitude indicator pickoffs or the heading bug input from Dg. I've said it before and I will say it again 90% of the problems are caused by the split pin contacts in the blue or the gray connectors making intermittent contact. Specially and very much specially after somebody has been behind the panel fooling around with harnesses and stuff 1 Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted September 3, 2017 Report Share Posted September 3, 2017 The voltage test measures the internal friction of the servo motor and gear train. The test is done by hooking a verable power supply to the servo motor and finding the lowest voltage that will spin the motor. The more friction the more power it takes to get it going. My hangar faries tell me most of the friction comes from the old grease in the planetary gearbox of the D.C. gear-motor. They tell me that it needs to be disassembled and all the parts need to be individually scrubbed with a brush and solvent and inspected with a high power loupe to make sure they are clean. Then reassembled with a low viscosity low volitity EP grease. They also said that polishing the commutator to a mirror finish helps. They claim you can get the starting voltage down to 0.5V if you do all this. Caution your hangar faries that the motor can be reassembled four different ways. Two make it turn the wrong direction and two have the magnetics in sub optimal locations reducing the torque of the motor. 2 Quote Link to comment Share on other sites More sharing options...
jetdriven Posted September 3, 2017 Report Share Posted September 3, 2017 It can also be improved somewhat by hooking up 12 V to the motor and running it in each direction for about 15 minutes Quote Link to comment Share on other sites More sharing options...
tigers2007 Posted September 3, 2017 Author Report Share Posted September 3, 2017 The avionics tech did just that - spun the motors around for a while. He also checked and coated the connection surfaces with Deoxit. The tech attempted to replicate the problem during the test flight and they couldn't find any issues. It worked great after the avionics upgrade for about five flight hours. Sounds like it's time to have a voltage test performed. And thank you all for the responses. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
tigers2007 Posted September 25, 2017 Author Report Share Posted September 25, 2017 Well I did about six hours over four legs the past couple days. I played with the Century IIB immensely. I determined this: 1. When in Autopilot mode (wing leveler mode?) without the NAV coupler, it seems to fly just fine. It is a pain in the ass and in my opinion worthless without being coupled to a specific heading. I suppose it has value in a panic situation. 2. I spun the DG heading bug around like four times each way. All of a sudden the NAV coupler function worked fine....for about ten minutes. I suppose I'll have someone look at the wiring one last time just in case. Otherwise I'll have the DG pulled and OH'd. I'd rather put in a G5 pair but that is about 8 AMU's more than I want to spend. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
jetdriven Posted September 25, 2017 Report Share Posted September 25, 2017 I have a friend with a DG that processes too much but maybe you can use it to diagnose your problem. Also, 1c388 radio couplers are really cheap. eBay is a good source. Quote Link to comment Share on other sites More sharing options...
tigers2007 Posted October 6, 2017 Author Report Share Posted October 6, 2017 I believe that the problem is solved. Apparently both of the ailerons we're not rigged correctly (both had a slight and uneven positive "droop"). During the last annual inspection at the MSC, they replaced pushrod tubes including the ones that link directly to the ailerons. Apparently no one ever checked to see if the ailerons were neutral when the yokes were centered. I always notice that I needed to hold pressure on the yoke to keep it from rolling to the left. This apparently made the century unit upset. I have logged about six hours with zero autopilot problems. This explains why the previous club owner insisted that they never had a problem with the auto pilot system before. Sent from my iPhone using Tapatalk 4 Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 6, 2017 Report Share Posted October 6, 2017 Nice Pirep, Tigers! Best regards, -a- Quote Link to comment Share on other sites More sharing options...
ChoperPilot Posted November 25, 2019 Report Share Posted November 25, 2019 On 9/2/2017 at 4:32 PM, tigers2007 said: The roll knob works I suppose; if I turn it to the opposite direction it will change the roll to that direction but it will not stabilize if I put the knob back in the middle. It just seems to want to remain in a maximum turn. Note that it isn't trying to do a barrel roll - it just wants to turn 15 degrees one way. Maybe the connection to or within the AI is kaput? I suppose I could just throw in a G5 AI for now and see if that results in a win-win. Sent from my iPhone using Tapatalk G5 AI is not connected to Century analog AP's. This G5 upgrade you still need to keep vacuum AI working properly to control Century AP's. On the other hand, G5 HSI has an option of roll steering coupler (GAD-29B) which will allow you to retire the vacuum DG, but not the AI. Quote Link to comment Share on other sites More sharing options...
tigers2007 Posted November 25, 2019 Author Report Share Posted November 25, 2019 ChoperPilot welcome to the Mooneyspace Forum and thanks for your input. Two years have past and Garmin still has not indicated that they will ever allow the G5 to give attitude data to the legacy autopilots. I believe there will be an all-in-one solution in the future as there is a serious demand. In addition to Aerovonics, there is some Italian company moving forward out of the blue with an AI solution. Maybe they'll take the lead. 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.