Removing the Windshield mounted OAT gauge

[redcatcher27]

I had the EI CGR-30P/C combo installed during my last annual.

I can now remove the OAT gauge on the windshield, since the CGR-30C includes a fuselage mounted OAT probe and readout. 

What's the best way to plug that hole in the windshield from the old OAT gauge?

[chriscalandro]

Why bother?  Why not just keep it?

[47U]

2 minutes ago, chriscalandro said:

Why bother?  Why not just keep it?

I think removal is a valid question.  I discovered my windscreen temp gauge has a 5 degree error. To read it, I have to move the visor, crank my head over to an obtuse angle, tilt my head again to focus my bifocal glasses on the needle and digits,, all to see a 5 degree error.  I say, get rid of it and gain the 0.005 mph (estimated) speed gain.

I’m not sure there’s a clean way to plug this hole.  Appropriately sized screw with washer and o-ring?  Plugging the hole with plexi/acrylic approved welding methods seems over dramatic. I thing I’d go with a piece of clear speed tape, inside and outside and call it good.  Replace as necessary as it deteriorates due to the elements.

tom

 

[Guest]

2 hours ago, redcatcher27 said:

I had the EI CGR-30P/C combo installed during my last annual.

I can now remove the OAT gauge on the windshield, since the CGR-30C includes a fuselage mounted OAT probe and readout. 

What's the best way to plug that hole in the windshield from the old OAT gauge?

There is a product called Acrifix solvent used by glider guys to repair cracked canopies.  This mixed with some dust/fillings from an old windshield to make a paste to fill the hole?

Clarence

[MikeOH]

My plane had an old school OAT installed in the pilot side window, but the hole was plugged when the PO installed  the Insight G3.  I don't know how easy to see your OAT is in the windshield, nor the ergonomic ease of reading your new CGR-30C, but I sure wish I had the old OAT.  They are so much easier to read than my G3. Maybe consider those factors before summarily yanking it out.

You can orient an OAT gauge so that 0 degrees C is at the top; a quick glance and you can tell if you are close to freezing.  Like setting your tach so red-line is at 12 o'clock (oh, wait...no one knows how to drive a stick anymore, nevermind)

Edited April 28, 2020 by MikeOH

[gsxrpilot]

Those OAT probes sticking out through the windshield are one of the ugliest looks on any Mooney. That's more than enough reason for me to remove it.

I think I've got an OAT display on 3 and maybe 5 different instruments in the cockpit. It's like anywhere I look, there's an OAT readout. Some of them in C some in F. 

Anyway, good onya for pulling that ugly wart off your windshield.

[GDGR]

On that note.....

I’m getting new glass from GLAP next week. Is this eye sore already cut in? If not, where do I stick my OAT Gauge for the EDM900?

[carusoam]

Get on the phone immediately... so they don’t accidentally have the hole drilled already.... 

Fixing acrylic windshields probably has a product like Doc described already... Ask the GLAP people... they have many answers for these types of questions and tools, and scratch fixers.... for sale.

Expect that the hole gets added in the field...

But know... an expensive mistake occurs when some new mechanic hasn’t drilled an acrylic window before....

Expect multiple MPH gain... probably wishful thinking...

Losing a really good visual detector of ice... serious challenge...

There are several good places for OAT probe for the JPI... look to where the modern Mooneys placed it mid way out, under the wing.... its a long wire run...

Next best is hiding in the NACA duct near the instrument panel... you will see many planes do this... unfortunately the OAT value it reports can be a few degrees off so close to the engine.... or having the sun beat down on it...

PP thoughts only,

-a-

[cctsurf]

9 hours ago, GLJA said:

I’m getting new glass from GLAP next week. Is this eye sore already cut in? If not, where do I stick my OAT Gauge for the EDM900?

I don't know about GLAP, but the one piece windshield (not 201 style) we installed on my 'C was not drilled in any way when it arrived.  I believe that is universally true.

[hypertech]

9 hours ago, GLJA said:

On that note.....

I’m getting new glass from GLAP next week. Is this eye sore already cut in? If not, where do I stick my OAT Gauge for the EDM900?

The shop that did my EDM900 install stuck it out the side NACA duct without talking to me.  I was super annoyed.  Later, I had it moved out to an inspection panel int he right wing, where the ovation factory gauge was.  Its bigger but at least now its not an eyesore and it should be slightly more accurate in the shade and away from the exhaust.

You need to use special thermocouple wire.  JPI has it available in standard lengths and they will also make you any length you want (and put the pins on).  25 feet is what I ordered.  I haven't looked in the wing myself but I did not get any complaints from the shop that did the relocating of it being either too long or too short or any notes from my recent annual that they was a pile of excess wire in there.

[cctsurf]

13 minutes ago, hypertech said:

I haven't looked in the wing myself but I did not get any complaints from the shop that did the relocating of it being either too long or too short or any notes from my recent annual that they was a pile of excess wire in there.

The thermocouple wire can be cut, it just can't be soldered to be extended...  They do a connection with crimp connectors and terminals to connect the sensors to the thermocouple wire.  I would think that this could be done to extend the thermocouple wires as well....  What you did in getting new wires would probably be better.  How much did they charge you for the new wire?

[hypertech]

23 minutes ago, cctsurf said:

The thermocouple wire can be cut, it just can't be soldered to be extended...  They do a connection with crimp connectors and terminals to connect the sensors to the thermocouple wire.  I would think that this could be done to extend the thermocouple wires as well....  What you did in getting new wires would probably be better.  How much did they charge you for the new wire?

I don't remember exactly.  I think it was a bit high for a piece of thermocouple wire but having it ready to go with the right ends on so it was plug and play for the shop probably saved me more time in labor than the premium on getting the part from JPI.

[N201MKTurbo]

Just now, cctsurf said:

The thermocouple wire can be cut, it just can't be soldered to be extended...  They do a connection with crimp connectors and terminals to connect the sensors to the thermocouple wire.  I would think that this could be done to extend the thermocouple wires as well....  What you did in getting new wires would probably be better.  How much did they charge you for the new wire?

I work with thermocouples all the time. You can extend thermocouple wires by soldering, if they will solder. Almost everything in aviation uses K thermocouples and they solder OK. The joints are not super critical in our applications because a few degrees off isn't a big deal. The best way to splice them is to tightly twist the wires together before soldering. this will not form a thermocouple at the splice. If there isn't intimate contact between the conductors you will get a conductor, solder thermocouple and then a solder conductor thermocouple. they will be in opposite polarity and will cancel and the only error will be caused by the temperature difference between the two junctions. considering the two junctions are a few microns apart, there won't be much of a temperature difference, therefor, not much error. I have found if you twist them, then stick the twisted wires in one end of a butt splice and crimp it on the twist, you get a secure, error free splice.

[cctsurf]

3 hours ago, N201MKTurbo said:

I work with thermocouples all the time. You can extend thermocouple wires by soldering, if they will solder.

I stand corrected.  I was working from memory from working on my JPI.  The thermocouple wire packs all have big warnings on them about soldering and using copper wire to extend them.  From rereading their literature, they mention that zinc chloride flux is necessary when soldering the thermocouple wires.

[carusoam]

+1 on how hard it is to have TC wires altered...

it can be done... but it takes knowing how to do it... and attention to detail...

Some people don’t even know the differences of the wire materials...

Around here we have seen some copper wire used on an attempt to extend the TC wires... with the expected results...

The signal generated at the junction is measured in micro volts... tiny tiny signal... easy to get lost because of induced noise, extra resistance, or foreign materials...

PP thoughts only... not a mechanic...

Best regards,

-a-

 

[N201MKTurbo]

Just now, cctsurf said:

I stand corrected.  I was working from memory from working on my JPI.  The thermocouple wire packs all have big warnings on them about soldering and using copper wire to extend them.  From rereading their literature, they mention that zinc chloride flux is necessary when soldering the thermocouple wires.

You are correct, extending them with copper wires would add considerable error. They must be extended with the same type of wire as the thermocouple. I would follow their advice about flux. I've had success using rosin flux, but the zinc chloride is probably better. Just twist and crimp them and don't bother soldering.

[Lionudakis]

I just finally removed mine off the windshield, I used a small countersunk washer outside with a flush screw, a thin nut on the inside with another countersunk washer, a little silicone between them.  Hardly noticeable compared to the short probe and indicator on the inside.   I have a JPI900 and aspen E5 with OAT. 

[Ragsf15e]

23 hours ago, redcatcher27 said:

I had the EI CGR-30P/C combo installed during my last annual.

I can now remove the OAT gauge on the windshield, since the CGR-30C includes a fuselage mounted OAT probe and readout. 

What's the best way to plug that hole in the windshield from the old OAT gauge?

I removed mine about 5 years ago.  My mechanic used clear “packing” tape on the inside (I’m sure it was STC’d, PMA’d, and TSO’d aviation packing tape), maybe 1” diameter around the 1/2” diameter hole.  Then he filled the outside with silicone.  It’s not clear, but it’s not noticeable way up there either.  That’s lasted 5 years with no problem.  I don’t take any special precautions when cleaning or flying in rain.

[Sean S]

AC 43.13 has the correct methods to repair acrylic/plexiglass. In short the hole should be tapered and a plug made of thicker materiel bonded in and sanded flush. Done correctly the repair will be nearly invisible. Clear silicone is not one of the methods of repair in the 43.13. A screw/washer/nut combination is an acceptable temporary repair to next annual.

[vorlon1]

On 4/28/2020 at 5:43 PM, Lionudakis said:

I just finally removed mine off the windshield, I used a small countersunk washer outside with a flush screw, a thin nut on the inside with another countersunk washer, a little silicone between them.  Hardly noticeable compared to the short probe and indicator on the inside.   I have a JPI900 and aspen E5 with OAT. 

Looking to do the same thing. @Lionudakis Got a pic or two?

[pirate]

I left mine in, sure makes a nice ice detector........

[RobertGary1]

Mine recently totally destroyed my Bruce’s cover in a rainstorm. The face is so worn it’s not useful and I have both JPI and Garmin oat sensors now. Looking forward to getting rid of mine. 

[ryoder]

I would use it as an excuse to get new glass. The impact to the look is awesome. Also I'd recommend getting the solar tint option. I didn't and regretted it.

[Immelman]

Keep in mind that the temperature error may still be there with a digital probe fed to your favorite instrument. The error is called ram rise and is a function of airspeed. Although not significant at Mooney speeds, it is worth a few degrees.

Its one reason why in a turbine airplane (and at resultant speeds), icing is considered in visible moisture below total air temperature (TAT) of +10C.

I would contend that our OAT probes display something close to TAT.

Edited April 7, 2021 by Immelman

[tony]

On 4/27/2020 at 7:49 PM, redcatcher27 said:

I had the EI CGR-30P/C combo installed during my last annual.

I can now remove the OAT gauge on the windshield, since the CGR-30C includes a fuselage mounted OAT probe and readout. 

What's the best way to plug that hole in the windshield from the old OAT gauge?

just wondering, where did you locate the probe?