Hi Gilles,
Thanks for your ideas, see my answers to your questions in the txt
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> Do you mean, while engine was running ? During cruise, for instance ?
No, this is when I first turn on the master prior to engine start. I
have never had a problem in flight or after engine start up
>Are you sure the servo is so powerful as to overcome any cable binding
>or wastegate sticking ?
Lockwood Aviation tell me yes. John Hurst (Ex US Manager of Europa)
confirmed this.
>Have you tried disconnecting the cable at the servo end to observe
> what is going on at power on ?
Well, no, but given two independent confirmations I didn't think it was
worth the effort.
Also, this isn't a repeatable problem. It happens with the first
power up, but once it works it says working. So, I could go to all the
trouble to try what you suggest, but it I couldn't conclude any thing
for sure.
>If it growls, then it is trying to do its duty. What prevents it ?
>Cable ? Wastegate ? Stuck bearings inside ?
Well, it has been my observation that is always makes barely audible
"growling" noise when it is its "steady state" condition. It's not
sounding like it is straining.
>By the way, did you install it in the safe environment of the cabin,
>or in the engine compartment inferno ? (We chose the cabin for the TCU
>and servo).
Mine is in the cabin
>I would first remove it from the airplane, and conduct a close
>inspection and some bench tests.
I agree, a close inspection of the unit and the integrity of the crimp
connectors is in order. One theory I have is the feedback pot
on the servo might be faulty, may be the wiper is intermittent and
all it takes is an initial movement and its okay. Perhaps the engine
vibration is enough to do this.
I have inspected all of the cables in the engine compartment.
>BTW, the yellow light (if correctlly wired) might indicate a TCU
>malfunction ;-((
Yes, the cost of a new TCU would make the price of a servo look like
small change. I often think that most of the TCU's functionality
could be replaced by a 7 lb spring on the waste gate !!
Thanks for your input.
Paul
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