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John Cooper's description of making phenolic hard points is right on!
What isn't said is that the round hard point seems to me that would
be somewhat stronger than a square one if only because there are no
corners to give rise to stress concentrations. Besides, using the
tools described, e.g., hole saws, etc, sure makes them simple. I used
the methods John describes, with one further thought: using the same
size hole saw for cutting the plugs *and* cutting the hole in the
pre-preg provides a clearance (width of the saw kerf) to insure a
complete surround by flox. The kerf allows you to see that it's filled
in all around - not sure if that's so important, but it was to me.
Also, this allowed me to leave the ragged edges on the plug that form
when cut out with the idea that it would improve the bond strength.
Along the same lines, there were quite a few places where I wanted a
neat hole thru a prepreg panel that wasn't necessarily structurally
involved and where I didn't want a lot of flox to surround the hole
(weight). I used hollow fiberglass arrow stock. The most common has
an ID that fits #10 and smaller hardware. Drill a clearance hole for
the shaft OD and glue in a short piece with flox so that it protrudes
a bit from both sides of the panel. When cured, sand the protruding
ends level with the surface and you've got a very neat, finished hole.
On my 235, I used this method to provide the screw-holes for attaching
non-structural panels such as flap mechanism and rear push-rod tunnel
covers, etc. I also used it to make feed-throughs for the Nylaflow
rudder cable conduits at the rear of the fuselage. It's quick, easy
and neat.
To John Cooper on the subject of running the #10 wire for the gear
pump direct to the battery. OUCH! A permanently hot, unprotected
wire running thru the cockpit, or anywhere in your airplane, for that
matter is not such a good idea, for your health and any unsuspecting
passengers you might carry. Even in glass airplanes, a short to a
ground return can happen, vibration over time, can eat through
insulation. And a short across the battery will dump a destructive
amount of current instantly and the results will be spectacular!!!
Like fire, smoke and ultimately, white hot bits of molten copper
bouncing around down there under your seats, probably right in there
with all the other wires in the center tunnel. You have to wait for
the thing to turn itself off because you can't. If you presently use
a 30 amp fuse that you can jerk out to protect your pump, why not
also play it safe and put in, say a 60 amp fuse or breaker right back
at the take-off point. The thing won't do anything under normal
operation, but will clear a short on a battery - what the heck, you
certainly won't be wanting to repower the circuit in the air under
those circumstances anyway, and it's easier to install than trying to
stay calm when your butt's on fire!
Did someone, in the last few weeks mention they had a 320 cowl for
sale? If so, what is the material and version? Also, if so, how much were you asking and can it be shipped safely (assuming we are
too far apart for it to be picked up - I'm in the LA area)? As I've
mentioned, I plan to install a 320 style cowl on my plane some time
in the near future. Appreciate any input.
Cheers,
Dan Schaefer
N235SP
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