Voltage, EDM-700, trim switch follow-up

When I started Atlas yesterday I watched the voltage on the JPI and
the EI volt meters. It was pegged right at 14, which my A&P says is
nominal. It drops to 13.4 or 13.5 in cruise, which he also says is
fine.

So, the JPI EDM-700 is now enroute back to JP Instruments in
California. The tech I spoke with said that display problems (missing
LED links) were rather common, and that their turn-around time was
just 3 or 4 days. $150 plus shipping.

The unit is almost five years old, so I guess I shouldn't be too
upset.

Our trim switch, which has been inop in the aft direction for months,
turned out to be a somewhat unusual problem. My A&P took the rocker
switch apart, and found that someone in the distant past had put a
little piece of copper sheet, barely thicker than tin foil, over the
screws that are supposed to actuate the switches, apparently in an
effort to help make more consistent contact.

It may have been part of the original switch assembly, although it's
hard to imagine such a kludge. Anyway, somehow that piece of copper
had shifted, and was no longer making contact with the aft trim
switch. (The trim rocker is actually two switches; one for down, one
for up.) He experimented with various fixes, and ultimately ended up
cutting a razor blade (the only thing we found that wasn't too thick)
to size and replacing the piece of copper. He also discovered that
the aft switch itself was slightly askew in its mounting.

The combination of realigning the switch, and installing the new
"contact piece" made everything work again.

Then, he fixed something that has aggravated me for five years. The
trim switch/push-to-talk mounting plate has had a sheared mounting
screw since Day One. The previous owner had "fixed" this by attaching
the plate with a piece of strong tape. I had done him one better, and
RTV'd the mounting plate to the yoke, which worked perfectly for years
-- until I had cut it off to examine the inop switch.

This was months ago. In the interim, I went back to the "tape" method
-- which didn't hold well or last long. Thus, for the past two
months, using the push-to-talk meant holding the unit with your thumb
whilst pushing the talk button. This often failed, of course,
resulting in the switch plate moving, and us stuttering on the radio.

Yesterday my A&P drilled out the broken screw head and tapped a new
screw. Voila! For the first time since we bought Atlas in 2002, the
yoke is as designed, and everything works as intended.

Best of all, I didn't have to buy a stupid Piper trim switch, to the
tune of over $600.

Today, we're installing the JPI outside air temperature probe that I
purchased last May. We're gonna install it like Jack Allison did,
out in the left under-wing inspection panel -- an elegant install
compared to the usual "drill a big hole through the side of the plane"
method that most people use. It means removing the pilot-side
interior panels -- a giant pain -- but in the end it'll be a lot
nicer.

Of course, until we get the EDM-700 back, the probe won't be
registering much. g

Once that's installed, I'm planning to remove the ugly through-the-
windshield temperature probe. I've heard that you can simply put a
piece of masking tape over the hole (on the inside) and fill the hole
with clear RTV (removing the tape after its dry, naturally!) -- but
has anyone here actually done that?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"