> 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
>
Do you confirm the MP always stays within specified limits ? At
take-off, for instance ?
If so, have you considered the "yellow indicator failure" hypothesis ?
>
>
>> 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.
>
If they did not examine your setup, I would not trust them too much on
that...
What is sure, is that if the wastegate is stuck, the servo won't be
powerful enough. It happened to some pilots I know, and sure enough, the
servo could not overcome the friction.
>
>> 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 were my airplane, I would first make sure it is not the cable or
wasegate.
Disconnecting the cable is no big deal.
> .....
> 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.
Could be, that is if it is the servo...
Best of luck in your troubleshooting,
Best regards,
Gilles
http://contrails.free.fr
|