Hi Mark,
It's a pity Mark, that you have not checked the max DC specification of
those microswitches. I am afraid they are even more underrated as their
circuit breaker specification. I am also disappointed that you are not
willing to comment on my "indoor use only" comment for these switches.
I had tested the prop before when new, and did not test it after the
repair. Maybe i was convinced that Woodcomp would have done a proper
job. My mistake. Your scenario of the fatal flight could be possible, or
not because your controller's pulse ratio would limit the max energy the
motor would pull on full power.
I think that Paul has now a good picture of the quality of the Woodcomp
after sales service now. My god, you will need it. When ordering the
prop from them do not forget to order spare microswitches, spare gears,
a spare motor spare diodes and ask them if you may change their
specification to a 20 A circuitbreaker.
Add a full fine to coarse excercise to your checklist, and check before
every flight that the microswitches are still in one piece. It's a pity
you will have to unbolt the prop for that, but hey, you have saved a
couple of thousand.:-)
Regards,
Jos Okhuijsen
27.6.2011 17:35, Mark Burton kirjoitti:
> --> Europa-List message posted by: "Mark Burton"<markb@ordern.com>
>
> Hi,
>
> I have nothing to say re the suitability of the microswitches/diodes used by
Woodcomp in the SR3000. However, from what I know about the characteristics of
the scimitar bladed SR3000 fitted with either the reversing or feathering
options,
I feel that they are unlikely to have been the cause of Jos' accident.
>
> Let's consider some facts:
>
> Fact #1 - Woodcomp specified that a 10A circuit breaker should be used with
> that
propeller and I believe that's what was fitted to Jos's aircraft.
>
> Fact #2 - under heavy load (high engine power, pitch motor stalled or moving
very slowly), the SR3000 pitch motor is capable of drawing more than 10A.
>
> Fact #3 - Jos's propeller had recently returned from the factory and (Jos,
> please
correct me if I am wrong), had not been checked to see that the fine limit
microswitches were correctly set so that the aircraft would be flyable with
the pitch stuck on fully fine.
>
> Therefore, it's possible for the C/B to pop simply by applying enough load to
the pitch motor. If it pops when the prop is fully fine, expect trouble.
>
> Regards,
>
> Mark
>
> PS - I informed the factory in 2007 that the scimitar bladed SR3000 required
an excessive amount of current to go coarse . Nothing came of it.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=344245#344245
>
>
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