CHT probe + resistor installed (final)

To finish an earlier thread I'm reporting on the install of a replacement
CHT probe in our Aztec. For those who didn't read the previous edition, the
left engine CHT probe in our Aztec failed and I started searching for a
replacement for the old AC Spark Plug Co. probe. A couple parts houses and
an instrument repair company took turn explaining my options. Since the
gauge is also an AC gauge and AC doesn't make either any more, the
replacement probe will not work with the AC gauge unless the gauge is
removed and sent to an instrument repair company to be re-calibrated for the
replacement Rochester probe.

This problem surfaced in the late 1970's for owners of early model Bonanzas,
Pipers, and Rockwell Commanders. One enterprising Bonanza owner
experimented with different size resistors wired inline with the probe. He
discovered that an 82ohm resistor in combination with the Rochester probe
would produce accurate readings on the AC gauge. So after talking with an
instrument tech who was familiar with the combination and who had sold many
of them during the past 10 years, I thought I'd give it a shot.

Long story short, it works. I found a pack of 25 new 82ohm 2W 5% flame
proof ceramic resistors on ebay for less than $5 and Aircraft Spruce had the
Rochester probe for $54. I figured that even if the combination didn't
work, I still needed the probe and would give it a chance before I spent
several hours with my upper body crammed up behind our panel pulling the 6
pack gauge cluster.

Tonight I installed the probe and attached the wire. I had already wired
the resistor and protected it with heat shrink. After installing, I checked
the amperage draw on battery power only and it measured 94.3mA, compared to
1.05mA without the probe attached. So I knew the probe was drawing current.

Taxi, runup, and test flight showed that the left gauge matched the right
gauge almost exactly. I didn't have the time or the equipment with me to
check it in an oil bath, but for now it looks like it works as advertised.

Jim Burns

Taxi, runup, and test flight showed that the left gauge matched the right
gauge almost exactly. I didn't have the time or the equipment with me to
check it in an oil bath, but for now it looks like it works as advertised.

Ingenious solution, Jim.

Is one of your partners an A&P? You guys sure seem to find innovative
solutions to things!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

In years to come, it's going to take a huge collecive knowledge base to
keep
our old birds in the air. Imagine trying to do it without the internet.

When we bought our Warrior in '98, I was just starting to explore the
aviation newsgroups. Because I was so ignorant -- and there was literally
no way to get the knowledge-base necessary to own an airplane, other than
the "school of hard knocks" -- I was fleeced by an unscrupulous FBO to the
tune of $5K for an annual.

Had I known then what I've learned here (and in other places on the
internet), I could have easily cut that bill in half.

IMHO, rec.aviation should be required reading for 12 months prior to
purchasing your first plane.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Is one of your partners an A&P?

Oh sure... you're just trying to open me up for the ole' Holiday Inn Express
routine huh? I wouldn't do that to a REAL Inn Keeper!!

We've got several good friends that are A&P's, so anything we dream up gets
run through them. Credit for this one goes to a fellow in the American
Bonanza Society over 20 years ago, and for a parts guy in TX that I use who
had this little tidbit stuck away in some back corner of his brain AND
remembered another TX instrument house that actually sold the parts. All
done on the internet via email, ebay, and Aircraft Spruce.

In years to come, it's going to take a huge collecive knowledge base to keep
our old birds in the air. Imagine trying to do it without the internet.

Jim

I was fleeced by an unscrupulous FBO to the
tune of $5K for an annual.

Had I known then what I've learned here (and in other places on the
internet), I could have easily cut that bill in half.

Ohhhh you just hit a sore spot. Although it all worked in our favor, I
still feel terrible about how the previous owner of our plane was treated.
He was nice enough to give us the invoices for the past 4 annual inspection
and maintenance.


IMHO, rec.aviation should be required reading for 12 months prior to
purchasing your first plane.

Ditto!!

Previous owners annuals on our Aztec:
2001 = $46972.48 includes one rebuilt engine for $14173.50 after core
charge refund.
Also includes full set of 3 WRONG size tired and $400 to install
them
Also includes $1500 annual inspection fee, and this is strictly
for the inspection per Jim Weir style, no maintenance or repair work, wait,
it's worse than that! There is a separate entry and labor charge for each
AD compliance, several are strictly visual inspection AD's, but there is
actually a line item labor entry for each AD verification and compliance!
You would think that if only a visual inspection were necessary to comply
with the AD, $1500 would cover it!

2002 = $18694.33
2 cylinders replaced on left engine
balance labor and small parts

2003 = $9933.99
New exhaust both engines

2004 = $6562.49
1 cylinder repaired

Each year, 3 years in a row they replaced a little rubber cabin door stop on
the right nacelle, $40 per pop. First time it blew away on ours, I replaced
it, drilled 2 holes in it, counter sunk them and bolted the ******* on then
siliconed the holes over. It will never come off again and there will never
be another shop screw the planes owner out of $40 for a 2 inch piece of
rubber.

2005 = $2441.00
Myself and my partners took most of a week off from work and did
anything and everything we could.
Includes all A&P/I labor, including to install new windshield.
No major problems found.

Jim

Previous owners annuals on our Aztec:
2001 = $46972.48
2002 = $18694.33
2003 = $9933.99
2004 = $6562.49

Holy cow, Jim! You can buy a whole Aztec for that amount!

Man, I'm glad I don't own an older twin....
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

The previous owner simply turned it over to the shop and gave them
carte-blanche. The invoices tell the tale. They took advantage of him
pretty bad. But as a result, we've got an old airplane with an enormous
amount of new parts. I don't have a problem with an owner wanting
everything done that needs to be done, but the invoices show that there
wasn't very much owner consultation, input, or assistance.
Jim

"Jay Honeck" wrote in message
news:%GXTe.93333$084.58400@attbi_s22...
Previous owners annuals on our Aztec:
2001 = $46972.48
2002 = $18694.33
2003 = $9933.99
2004 = $6562.49

Holy cow, Jim! You can buy a whole Aztec for that amount!

Man, I'm glad I don't own an older twin....
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

IMHO, rec.aviation should be required reading for 12 months prior to
purchasing your first plane.

I read it for 3 years prior to buying my Warrior and still got fleeced
for 8 grand at the first annual. So reading is good but sometimes you
still take a few hard knocks.

--Rick

I read it too, for several years, before purchasing our Mooney and still
had a $8,500.00 first annual.

Jon Kraus
'79 Mooney 201
4443H @ TYQ


Rick Beebe wrote:
IMHO, rec.aviation should be required reading for 12 months prior to
purchasing your first plane.


I read it for 3 years prior to buying my Warrior and still got fleeced
for 8 grand at the first annual. So reading is good but sometimes you
still take a few hard knocks.

--Rick