banner
banner

29 Mar 2024, 01:34 [ UTC - 5; DST ]


Concorde Battery (banner)



Reply to topic  [ 10 posts ] 
Username Protected Message
 Post subject: CHT probes for a C310
PostPosted: 21 Jan 2020, 21:19 
Offline


User avatar
 Profile




Joined: 11/30/10
Posts: 4263
Post Likes: +3718
Company: Flagstaff-Williams Dev. LLC
Location: KCMR
Aircraft: 1965 310J
1965 Cessna 310-J with IO-470-U engines. The engine instruments have changed so much in the last 50+ years that Im having difficulty finding the right part number for the CHT probes.

On the Bayonet fitting is a Cessna number S2497439, but that doesnt correspond to anything in the IPC. Back in the day, it was referred to as a temperature 'bulb'. Not a Thermocouple or an RTD.

I still havent pulled the unit as Im waiting on weather to cooperate.

Is any one familiar with this PN S-2497439? Im thinking it may be an RTD because of the gauge behavior. It reacts normall from cold up to about 300dF (during runup). Then, after runup, when I reduce RPM, the temp rises (as it should with lower airflow); it begins to dance between 310 and 400. up and down.

At first, assuming it was an RTD, this would mean an intermittent Break due to thermal expansion. Im guessing the resistance jumps up on either an open circuit or possibly a short.

If this were a thermocouple an open would result in "0" milivolts and the gauge would drop to 0. If it were a short, it may/may not go full scale depending on the resistance to ground and which side of the lead was shorted.

As I understand it, Barons with this engine use an RTD with a bias resistor. Is this similar? Any information is better than guessing.

Thanks.

_________________
All my friends are here. I know this because all my enemies are dead. :)


Top

 Post subject: Re: CHT probes for a C310
PostPosted: 22 Jan 2020, 03:30 
Offline


User avatar
 Profile




Joined: 04/07/13
Posts: 556
Post Likes: +388
I pulled the left engine on my C310F (IO-470-D) last fall to repair a cylinder and had to disconnect everything, including the bayonet CHT probe. It had yellow and red wire leads, which are characteristic of a K type thermocouple. I too have an OEM CHT gauge that flips out from time to time in cold weather. I haven't had time to swap the plugs on the gauges to see it is a gauge or probe issue yet. My 3 in 1 engine gauges, which house the CHT, are adjacent to each other but I don't know if the harness will allow a plug swap easily.

Thinking back, I recall one of the leads from the probe was grounded to a rib, below the intake riser on cylinder #2, in the nacelle. This is not typical wiring for a millivolt thermocouple, as it introduces a third dissimilar metal junction. Usually both leads run directly to the gauge.

I am currently away from shop but when I get back, as curiosity has gotten the better of me, I'll do some research with a heat gun and a DVM to see what I observe about the probe.

_________________
No fighter jet - No Pepsi!


Top

 Post subject: Re: CHT probes for a C310
PostPosted: 22 Jan 2020, 12:09 
Offline


User avatar
 Profile




Joined: 11/30/10
Posts: 4263
Post Likes: +3718
Company: Flagstaff-Williams Dev. LLC
Location: KCMR
Aircraft: 1965 310J
Thanks Gary. If the temp in the hanger gets above 40 today, Ill start the removal process.

I also ordered a bag of grommets and fiberglass sleeves for the wire's within the engine bay.

The prop cable and CHT seem to run along the lower engine support below the induction tube. I'll see about re-routing and securing it better. I've been practicing my hand using Lace-cord as it looks and lasts better than zip-ties. We'll see if I can get my hands in there.

-Bud

_________________
All my friends are here. I know this because all my enemies are dead. :)


Top

 Post subject: Re: CHT probes for a C310
PostPosted: 22 Jan 2020, 12:34 
Offline


User avatar
 Profile




Joined: 04/07/13
Posts: 556
Post Likes: +388
I happen to have the IPC for the C310 F thru K on my traveling laptop. The part number for the CHT probe is 0813601-4 as illustrated by item 10. (don't ask me how I managed to find it :) )
Attachment:
24-30-00-03P1.jpg
Attachment:
24-30-00-03P2.jpg



Cessna Direct says this has been superceeded by 0813601-6 which sells for the obscene price of $1,181 :bugeye:

I pretty sure this is a common part which can be cross referenced given some research. It's not like they were using spare rocket parts from NASA in the early 60's to build these planes.


Please login or Register for a free account via the link in the red bar above to download files.

_________________
No fighter jet - No Pepsi!


Top

 Post subject: Re: CHT probes for a C310
PostPosted: 22 Jan 2020, 12:43 
Offline


User avatar
 Profile




Joined: 11/30/10
Posts: 4263
Post Likes: +3718
Company: Flagstaff-Williams Dev. LLC
Location: KCMR
Aircraft: 1965 310J
Gary, and thats not the list price. ~$1,415!! Another vendor will give me a break at $1,273.

yeah, if its a type K thermocouple, we may be looking for a brand X replacement.

Thanks.

-Bud

ps. Looks like Aircraft spruce has them for $999.95. Almost an AMU.

_________________
All my friends are here. I know this because all my enemies are dead. :)


Top

 Post subject: Re: CHT probes for a C310
PostPosted: 22 Jan 2020, 13:08 
Offline


User avatar
 Profile




Joined: 04/07/13
Posts: 556
Post Likes: +388
At the risk of :deadhorse: the only way I'll know for sure what this probe is, will be by hands-on measurement. Heck, I have two to test and my right engine ain't misbehaving. The descriptions in many of the cross-references that I've found say "resistance". (see example below). I'll post my findings when I get back to the shop in February.
Attachment:
SpencerCHT.jpg


Please login or Register for a free account via the link in the red bar above to download files.

_________________
No fighter jet - No Pepsi!


Top

 Post subject: Re: CHT probes for a C310
PostPosted: 22 Jan 2020, 17:15 
Offline


User avatar
 Profile




Joined: 11/30/10
Posts: 4263
Post Likes: +3718
Company: Flagstaff-Williams Dev. LLC
Location: KCMR
Aircraft: 1965 310J
Well, I was able to remove the suspect part and get it under a magnifying glass.

It turns out the "Part number" is actually a Patent Number 2497439. Issued in 1947 To Tomas A. Edison. The patent ran out in 1967; two years after my aircraft was built. It is the original 0813601-1 the current dash no. is -6. 55 years for an electrical sensor is pretty good. It lasted through 4 engine and several swaps. Cant say much for the installation job as the failure mode is clearly the lack of the grommet used for strain relief.

Cheapest replacement with FFA-PMA is ~$400 through Aircraft Spruce; tho Im still lurking in the rabbit hole for a while to see what the alternatives are.

The "Tell" in diagnosing this thing was to disconnect the leads and use a multimeter to measure the voltage. A thermocouple will have a self generating voltage in the microvolt range. None present. When I turned the ships power on, the gauge went Full Scale. When shut off, the temperature reading slowly returned to 0 indicating an RC circuit was in play and not a simple voltage reader.

Wife says I should clean it up and mount it in a shadow box with the Edison Patent cover page and illustration. Try to get $400 on ebay.. :)


https://patents.google.com/patent/US249 ... =us2497439

_________________
All my friends are here. I know this because all my enemies are dead. :)


Top

 Post subject: Re: CHT probes for a C310
PostPosted: 22 Jan 2020, 22:00 
Offline


User avatar
 Profile




Joined: 01/18/13
Posts: 616
Post Likes: +477
Location: Tampa, FL
Aircraft: 2020 Gamebird GB1
Texas Air Salvage has some used parts.

Doesn’t say the price.

https://www.texasairsalvage.com/main_vi ... id1=228619

Try preferred air parts and White Industries, I’ve had good luck with both.

Butch

_________________
The only way to make more time is to go faster.
2020 Gamebird GB1
2015 Lockwood AirCam
KTPF/KVDF


Top

 Post subject: Re: CHT probes for a C310
PostPosted: 27 Nov 2022, 13:01 
Offline


User avatar
 Profile




Joined: 11/30/10
Posts: 4263
Post Likes: +3718
Company: Flagstaff-Williams Dev. LLC
Location: KCMR
Aircraft: 1965 310J
Sorry for the late follow up on this problem/solution.

I eventually went down the rabbit hole to find out who actually makes these probes for Cessna (or Beech....nee Textron).

Long story short. My old Friends at Norwich Aero in Norwich NY.

Thier PN is Norwich Aero CHT Bayonet Temperature Probe 102-00007

This device is an RTD, resistance temperature device and has a room temp reading of 76 Ohm.

I found one on Ebay for $175 and snatched it up as quick as I could.

It tested out fine so I installed it. The Runup and testing still shows that my Right Engine is still 25F higher than the Left (the right one failed). So I tested the harness/probe and found the resistance a bit higher on the right than the left ....... Was it worth 25F? almost, so Im now looking for a splice or joint in the harness that makes this the root cause of the problem.

It turns out the grounding for the CHT probe on the left is different than on the right. The left is grounded directly to the frame in the engine bay, while the one on the right appears to lead back to the gauge (which then ties into the avionics ground (ie. frame).

I've been through this harness before. Its tedious, but a doable project.

_________________
All my friends are here. I know this because all my enemies are dead. :)


Top

 Post subject: Re: CHT probes for a C310
PostPosted: 27 Nov 2022, 19:37 
Offline


User avatar
 Profile




Joined: 01/18/13
Posts: 616
Post Likes: +477
Location: Tampa, FL
Aircraft: 2020 Gamebird GB1
I had an oil temp probe go weird on my 310F,, I secured the ground and the problem went away.

Butch

_________________
The only way to make more time is to go faster.
2020 Gamebird GB1
2015 Lockwood AirCam
KTPF/KVDF


Top

Display posts from previous:  Sort by  
Reply to topic  [ 10 posts ] 




You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  

Terms of Service | Forum FAQ | Contact Us

BeechTalk, LLC is the quintessential Beechcraft Owners & Pilots Group providing a forum for the discussion of technical, practical, and entertaining issues relating to all Beech aircraft. These include the Bonanza (both V-tail and straight-tail models), Baron, Debonair, Duke, Twin Bonanza, King Air, Sierra, Skipper, Sport, Sundowner, Musketeer, Travel Air, Starship, Queen Air, BeechJet, and Premier lines of airplanes, turboprops, and turbojets.

BeechTalk, LLC is not affiliated or endorsed by the Beechcraft Corporation, its subsidiaries, or affiliates. Beechcraft™, King Air™, and Travel Air™ are the registered trademarks of the Beechcraft Corporation.

Copyright© BeechTalk, LLC 2007-2024

.bullardaviation-85x50-2.jpg.
.dbm.jpg.
.gallagher_85x50.jpg.
.cav-85x50.jpg.
.kadex-85x50.jpg.
.boomerang-85x50-2023-12-17.png.
.MountainAirframe.jpg.
.planelogix-85x100-2015-04-15.jpg.
.camguard.jpg.
.wilco-85x100.png.
.bpt-85x50-2019-07-27.jpg.
.saint-85x50.jpg.
.Foreflight_85x50_color.png.
.Genesys_85x50.jpg.
.concorde.jpg.
.pure-medical-85x150.png.
.blackhawk-85x100-2019-09-25.jpg.
.Latitude.jpg.
.avionwealth-85x50.png.
.avfab-85x50-2018-12-04.png.
.midwest2.jpg.
.aviationdesigndouble.jpg.
.Rocky-Mountain-Turbine-85x100.jpg.
.aeroled-85x50-2022-12-06.jpg.
.blackwell-85x50.png.
.chairmanaviation-85x50.jpg.
.jetacq-85x50.jpg.
.tempest.jpg.
.headsetsetc_Small_85x50.jpg.
.Marsh.jpg.
.kingairacademy-85x100.png.
.stanmusikame-85x50.jpg.
.pdi-85x50.jpg.
.Wingman 85x50.png.
.Wentworth_85x100.JPG.
.jandsaviation-85x50.jpg.
.aircraftassociates-85x50.png.
.lucysaviation-85x50.png.
.kingairnation-85x50.png.
.airmart-85x150.png.
.shortnnumbers-85x100.png.
.ei-85x150.jpg.
.centex-85x50.jpg.
.one-mile-up-85x100.png.
.SCA.jpg.
.daytona.jpg.
.ABS-85x100.jpg.
.CiESVer2.jpg.
.geebee-85x50.jpg.
.tat-85x100.png.
.AAI.jpg.
.temple-85x100-2015-02-23.jpg.
.ssv-85x50-2023-12-17.jpg.
.sierratrax-85x50.png.
.traceaviation-85x150.png.
.wat-85x50.jpg.
.aircraftferry-85x50.jpg.