lml@lancaironline.net Mailing List Archive

Colyn, I agree with you. This is a case where the wiring should have been 12v to the trim system and it is 24v. A secondary finding was that the trutrak autotrim box needs some mods which can handle that kind of error which tells me there are probably a few more 24v systems connected to 12v Ray Allen servos. Once I correctly supply 12v to the trim system then I might sit down and consider some of the other trim safety things out there but getting the speed down and checking trim authority (as you said) is probably the best for now. I've had this airplane for 2 years and I've been reluctant to change anything until now. I am impressed by Trutrak's commitment to fix a potential fault. I know that a similar Honeywell KFC-325 issue would not be as forthcoming and certainly not as affordable to fix. Paul Spruce Creek On 2011-01-19, at 10:22 AM, Colyn Case wrote: > I don't know why you would want to rely on tru-trak to condition the trim voltage....because you would want it to work properly as manual trim too, right? > > This reminds me: I wired my system so that I can turn the auto-trim off and still use the manual trim. On a system with no auto-trim you would get the indication on the face of the auto-pilot telling you when to fix the trim. When I got my system up, this indication was wrong. Working with tru-trak we discovered that one of the signals was floating as a result of the design of the auto-trim box. Tru-trak gave us instructions for a field mod to fix this. If you are considering something similar you will want to ask about that field mod. > > Other thoughts about trim speed though: > 1) even though you can "blip" it, I think it beats the crap out of the relay deck when you use it that way. Better to have the speed mod. I remember being at HPAT one day when they had to switch out the relay deck in 409L after not very long (less than 2 years? don't quote me) in service. > 2) I don't know how to make safety-trim work with auto-trim. What will the auto-pilot do if it's trying to trim for 4-5 seconds and safety-trim stops it? My guess is it will keep its switch closed forever and safety-trim will fight back forever. I have to confess I never talked to safety-trim about this. > 3) Given all that, it seems like the most prudent policy is to make sure your trim travel is no more than it needs to be. > > > On Jan 18, 2011, at 11:45 AM, paul miller wrote: > >> Doug and Colyn: Yes, the trim servo is the Ray Allen unit which is only sold as 12v so it appears to be driven at 24v by my aircraft through the Trutrak box. The normal Ray Allen travel time is about 15 seconds from their website and I'm around 5-8 seconds. It would appear that Trutrak will mod the autotrim box to limit the output voltage to 12v but I've got a note into them to confirm this before I send it back. If that's correct Doug then the trim speed should be more manageable. This is also a safety issue because a 5 second full trim move is not easy to live with in a runaway situation. Will advise shortly. >> >> Paul >> Spruce Creek >> >> On 2011-01-17, at 7:57 AM, Douglas Brunner wrote: >> >>> Paul, >>> >>> This is a problem experienced by other Legacy pilots. >>> >>> I am also a 28V plane, but don't think the problem is due to the voltage. >>> My trim speed is good for takeoff and landing, but way too fast for cruise. >>> I have adapted to it by learning to "blip" the trim in flight. >> >> >> -- >> For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html > > > -- > For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html