Paul McAllister wrote:
>
> Hi All,
>
> I wish to purchase a vacuum pump and I was wondering what people were
> buying. Their are two products I am looking at, the Sigma-tek and the
> Airborne. The Airborne looks very much like the one that Europa sells, but
> I can't tell if I need a CW or CCW rotation pump.
In the Airborne, you need the 211CC, as the pump drive turns opposite
of the prop. I haven't heard that one's better than the other. Dry
pumps are problematic, period, and you're best off just OH or
replacing it at maybe 700 hours, need to or not. Even if IFR
reliability is not an issue, on catastrophic failure, you can suck
debris into the gyros due to typical relative pressures in the vacuum
system. Airborne appears advantageous, in that you can buy cheap
repair kits rather than replace.
Assuming you haven't installed the pump drive kit yet (Rotax P/N
999-578), you should get the service manual. It specifies the various
types of Loctite you need for the job, plus torque values and
cautions, and these issues are not trivial. You'll see that two
screws (pump gear and bearing hold down) _must not ever_ loosen in
service, or serious damage can result. In fact the M5 hold-down
screw (for the sealing plug, to be replaced with a roller bearing) is
Loctited so solid, on mine it won over a pro-quality, serrated tip
Phillips screwdriver. I had to Dremel/cut-off wheel a slot for a
big-ass slotted screwdriver to relieve the tension and crack it loose
(use plastic sheet to deflect the debris and replace screw and washer
of course). No virgin to breaking the little Easy-Outs, so I didn't
go that route.
The manual will specify a slide-hammer tool to pop off the prop gear
drive case, but just install two metric bolts in the threaded holes on
the sides of the case, and using a _plastic_ mallet, gently rap the
bolt heads, observing uniform parting of the case.
They specify tools to install the two bearings, but I found that a
3/8" bolt/nut, assorted washers, and appropriate size hex sockets for
a spacer pressed in the bearings and oil seal easily. Ditto for the
Rotax tool to hold the pump drive spline while you torque the pump
gear screw. I used a large screwdriver padded with duck tape, to jam
the gears, my only concession here to techniques known to "Bubba, the
Redneck Mechanic."
Remove the old Loctite from all the bolts, with other than a wire
wheel, for accurate torquing. The necessary metric Allen head socket
tools are not easy to find here, but I got mine from a mobile Snap-On
tool dealer. They, and likely others (Mac, Matco), have web sites for
direct ordering.
Enjoy the partial tear-down of your new, hopelfully to remain
in-warranty, ROTAX 91x!
Fred F., A063
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