TMB 850 autopilot problems
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So I installed the latest update today. I'm having issues with the autopilot.
The aircraft turns to the left always for some reason. I turn on the AP set heading and then put the AP on and
nothing works properly. Did the test thing and still same issue. The ailerons trim is perfectly set. Nothing works. -
The aircraft turns to the left due to the tremendous torque of the propeller in a single engine aircraft, which is why the rudder trim takeoff position is substantially to the right of center. As for the autopilot, I'm afraid that I will need more than "nothing works" to help you troubleshoot. If you're already familiar with the TBM, I assume you have the AP/TRIMS switch in the correct position for the autopilot servos to receive power?
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You are right, as I should have explain better.
From the rudder display in the cockpit, it shows right center as it is for the ailerons display.
Even without the AP, it's very hard to keep the aircraft straight.
Again after having the aircraft up, I use the AP like this; HD on, YD on and the AP on. The HD needle centered.
The aircraft does not keep the heading. It continue to veer left. I tries this on NAV mode, still the same issue.
When you start the AP from the switch, it does a self test, right? Do I still have to press the test button again or not? -
The high torque is not unexpected, and requires some getting use to adjusting your trim in the climb with such a high performance airplane. As for the autopilot, can you see what the flight director is doing? Does it look like it's properly commanding a turn towards the selected heading? No second autopilot test is necessary, but the autopilot master switch (left toggle, above the trim indicators) needs to be in the fully up position, not the center position. If you are still seeing problems, please share some screenshots or video, and I will be happy to take a further look.
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You don't need to press the test button, no. Follow the checklist, make sure the four gyro button are on. Then you have the radio master switch, AP master, and EFIS master switch. For takeoff, in low winds you can set the rudder between center and TO notch. In winds greater than 7-8 knots, put the rudder to TO line. You don't need to set aileron trim. If everything is setup correctly, the plane will maintain a heading with minimal pull to the left. Adjust the rudder trim to account for any pull to the left. The slower you are, the more rudder trim you will need, and as you build speed you will need to center the rudder. Watch the ball right below the attitude indicator/EFIS, and keep it centered. If the plane is trimmed, the plane will only pull a very little, and that can be countered with aileron if needed. I never use aileron trim however. With AP on, the plane will hold a heading or NAV/GPS route just fine, even if the ball isn't centered. You're just introducing more drag by not centering it.
The only thing I can think of is that perhaps you have some assistance setting on that are interfering with the plane. Yes, the plane does pull more than others I've used, but it is a normal amount of pull and certainly not uncontrollable or inappropriate.
Make sure these are on and the trim is set to TO, or close to it (it's centered here). The elevator trim works best at the bottom of the green for takeoff:
