Rick,
9 times out of 10 the brushes have oil on the slip ring or have worn until
barely contacting ( typically the outer ring brush wears first). In Manual,
you get direct battery current, so it will give you more juice to burn
through any corrosion/oil. Clean up the slip ring and check your brushes.
Normally you get red flashing lights with an open circuit, but not always,
because if there is some current, but not enough to move the prop, the red
lights don't flash and the prop doesn't work in Auto. (As I tell my
clients, Red lights are bad, don't takeoff, if in-flight, go to manual and
adjust the prop manually or by throttle to keep the RPM in limits and land
as soon as conditions permit and investigate.)
I have had three calls or comments since the weather turned cold. The oil
layer thickens up and coats the brushes. As brushes wear they also
distribute carbon to the inside of the brush block.
Oil helps hold the carbon as a current drawing sludge which acts like a high
resistance wire. Current can then jump between brushes and stop the prop.
It's basically shorting. Not good for the AC200 either.
Every oil change, check your brushes and slip rings, as any leak of oil will
often times go forward through the large hole you made in the front of the
cowl. It only takes a thin film of oil. Clean with acetone on a clean rag.
Clean the slip rings with scotch bright to remove corrosion. Wipe clean
again. Use air to blow off the brush area in the brush block. I pull the
brush block off and check the brush length on my annual or at 100 hours,
whichever occurs first, not just when the prop stops working.
Technique:
To help seal the prop from this nuisance oil film, use some fiberglass to
try to seal up the hole. To seal the hole, I have had success with using
silicone cowl seal (in sheet form with a fiber reinforcing to keep it stiff)
on the lower cowl. This silicone rubber gives me some flexibility when
getting the cowl off of a trigear. On the upper cowl, just make a 3 ply
sheet and allow to cure, then trim and fit to the shape and glass on the
upper inside... Go Fly!
If the pickup for the speed sensor goes bad, that freezes the controller.
The fine orange light should flash. If the speed sensor is bad, the brush
block usually needs to be changed.
If the controller dies completely, the internal fuse (a PTC that resets
itself) may have opened (at about 2.5 amps) killing power to the controller
until it resets itself by going manual, cooling, and then back to auto. If
you are using thick grease (Aeroshell 22) that can stiffen up as it gets
colder and cause a power drain, but that's unlikely. Cycle the prop in
manual and listen to the motor. If it is dragging, it may be too tightly
torqued or the grease is really thick. If the motor sounds good and free,
the AC200 is not getting power or internally dead. Check power to the unit
(CBs do go bad), if OK, check the circuit breaker on the side of the
controller. If that is OK, and cycling manual to auto doesn't reset it,
it's probably a dead AC200.
We often say the controller was reprogrammed, but often times the circuit
card is replaced.
Check the above and have a beer and dive into the manual. It's on line
also.
It's winter, in the northern latitudes, so stay healthy and let me know what
happens after troubleshooting the above... We're enjoying 75 degree weather
here in Florida.
Best Regards,
Bud Yerly
Custom Flight Creations, Inc.
US Airmaster and Europa Dealer
--------------------------------------------------
From: "Rick Moss" <Rkwmoss@gmail.com>
Sent: Monday, December 29, 2014 2:01 PM
Subject: Europa-List: Airmaster constant speed unit issue
>
> My 912S has an airmaster VP prop with warp drive blades and the airmaster
> constant speed control unit. Both have around 100 hours on them.
>
> Today upon takeoff fly flydat alerted me to an engine over speed
> (moderate; never exceeded 5900rpm). I slowed down a little and reduced
> power to keep the engine within limits, and climbed to altitude to
> consider the issue. The CS unit was non-responsive, however switching to
> manual enabled me to alter the pitch. Has anybody experienced this? I
> assume that if all connections appear good, I simply need to replace the
> CS unit?
>
> Rick
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=436408#436408
>
>
>
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