Problems with Rapco dry vacuum pumps.

Me,

I am (was) a kit builder. 200hrs PPL, now flying the
completed kit 18 months, 84hrs. Guess thats why
I am complaining since there was little "bad"
vacuum pump info available to me as a builder.
I do have a science/engineering background.
Hey, I am also a fellow Canuck but living in US now.

Wish I had the money back for all things I tried
that didn't work out as well.
------------------------------------------------
SQ2000 canard: http://www.abri.com/sq2000


wrote:
....
What's your experience?...

How about a slinger followed by a felt seal? The slinger can be made
from an o-ring. Felt will catch any tramp oil, is cheap, & can run dry.

If you have a homebuilt aircraft, consider this:

Pull the plugs from the engine. Put your ear on the pump. Have someone
slowly turn the prop. Listen to the vanes inside the pump fall from
the inside to the outside of the rotor slot. There should be a regular
"click" as each or the six, ( I think that there are six) vanes fall.

If you do not hear the vanes fall, they most likely are "hung up" due
to some contamination. Open the pump, and clean everything. Put it
back together. I use a little silicon seal to act as a gasket on the
back joint of the pump.
I think that the pumps fail when the vane gets sticky and refuses to
slide in and out of the slot in the rotor. I know that the slots in
the rotor will wear larger eventually, but I listen to my pump every
25 hours at the oil change and have had to clean the pump twice in the
last 250 hours. The pump now has about 800 hours on it.

Good luck.










On 21 Sep 2005 14:03:08 -0700, "nrp" wrote:

How about a slinger followed by a felt seal? The slinger can be made
from an o-ring. Felt will catch any tramp oil, is cheap, & can run dry.


Zenith CH-300 Driver.

Tim,

Wish you posted this before. I kind of suspected possibly cleaning it
but was afraid of messing it up. I sent it back to Rapco who refused to
warranty service it but gave me a discount deal on a new replacement
pump.

Tim Hickey wrote:
.....
If you do not hear the vanes fall, they most likely are "hung up" due
to some contamination. Open the pump, and clean everything. Put it
back together. I use a little silicon seal to act as a gasket on the
back joint of the pump.
I think that the pumps fail when the vane gets sticky and refuses to
slide in and out of the slot in the rotor. I know that the slots in
the rotor will wear larger eventually, but I listen to my pump every
25 hours at the oil change and have had to clean the pump twice in the
last 250 hours. The pump now has about 800 hours on it.
.....

How about a slinger followed by a felt seal? The slinger can be made
from an o-ring. Felt will catch any tramp oil, is cheap, & can run dry.

The felt will wear. It's used in many older aircraft wheel
bearings (even some newer ones, and it doesn't work that well. It has
to be saturated with grease to prevent water uptake, and thereby
attracts dust. If it soaked up oil it would become saturated and allow
the oil past.
Autos and trucks abandoned felt seals in the '40s and '50s.

Dan