PA28-235 heated pitot

Mark Hunter

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Mark Hunter
I have a 1964 Cherokee 235 and I need to install a heated pitot. Was the wiring in place when it was manufactured? Is there a reasonable add on part or kilt available?
Thanks
 
I have a 64 235, and mine has a heated pito tube as standard. But Looking at the parts manual it looks like it could go either way:

65797-05 E,F HEAD ASSEMBLY - Pitot (unheated)
69041-05 E,F HEAD ASSEMBLY- Pitot (heated)

E- Used on PA-28-140 with serial numbers 28-20281 to
28-24999 incIusive, PA-28-150, PA-28-160 and PA-
28-180 with seriaI numbers 28-1761 to 28-2477
incIusive, and PA-28-235 with seriaI numbers 28-
10487 to 28-10675 inclusive.
F- Used on PA-28-150, PA-28-160 and PA-28-180 with
seriaI numbers 28-2478 to 284377 incIusive, and PA-
28-235 with seriaI numbers 28-10676 to 28-11039
inclusive .

I'm guessing this depends on the option that was chosen when someone bought the plane. From the picture I'm guessing if you remove the existing head you can see if the wires are there.

Pito.png
 
Call Piper support direct with your aircraft serial number. Sometimes Piper would install provisions for various kits during production like for stall warning system. Piper should be able to pull up your original configuration. Afterwards if you need to install a whole kit then compare any STC offerings to the Piper kit.
 
Call Piper support direct with your aircraft serial number. Sometimes Piper would install provisions for various kits during production like for stall warning system. Piper should be able to pull up your original configuration. Afterwards if you need to install a whole kit then compare any STC offerings to the Piper kit.

And record that call so we can here it. “I want to know if you installed a wire that was connected to nothing for an option that was not purchased in a plane you built 1/2 a century ago.”
 
I guess you don’t know the history of Piper or how airplanes of that era were built.
While I haven't worked on as many Pipers as other aircraft I actually do know how aircraft of that era were produced along with a few other airplanes and helicopters.

And Piper along with other OEMs have been pretty good at supplying the configuration, ie, "a wire that was connected to nothing for an option," of their aircraft as they rolled off the production line either back in a bygone era or today.

As mentioned above, it's quite obvious by your comments you've never had a meaningfull discussion with any aviation tech rep.
 
While I haven't worked on as many Pipers as other aircraft I actually do know how aircraft of that era were produced along with a few other airplanes and helicopters.

And Piper along with other OEMs have been pretty good at supplying the configuration, ie, "a wire that was connected to nothing for an option," of their aircraft as they rolled off the production line either back in a bygone era or today.

As mentioned above, it's quite obvious by your comments you've never had a meaningfull discussion with any aviation tech rep.

Well we have to wait and see if the OPs wire is there or not. A whole lot easier just to look in the left wing for the wire.

What you also seem to discount is the removal of a wire leading no where by someone trouble shooting a problem.
 
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We put a heated pitot in our PA28-140 about ten years ago. The wiring was not there. That's about all I've got other than that we HAVE had good experiences calling and getting information and documentation from Piper.
 
I'm guessing this depends on the option that was chosen when someone bought the plane.

I could believe that. To handle something like 10+ amps at 12 Volts, it's gotta be heavy-gauge wire. So that adds cost and weight. If the original customer didn't order the feature, if I were the manufacturer, I would want to omit that heavy wire.
 
if I were the manufacturer, I would want to omit that heavy wire.
FYI: sometimes OEMs would build aircraft in block sets as they could use the wt/balance record of one aircraft for all aircraft in that block thus saving time of individual aircraft weighing. So there's always a chance a particular aircraft may have a system/provisions installed by the OEM during production.
 
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This might be simplistic, but wouldn't this be what they still use on new Cherokees?
 
This might be simplistic, but wouldn't this be what they still use on new Cherokees?
Thanks for the reply’s. The wires are not there and we need to install a whole kit
 
I have a 1973 Piper Cherokee 140 and the wires have been there, along with the circuit breaker, for almost 50 years. The only hardware required for adding pitot heat in my Piper Cherokee then would be the switch and two heater elements that slide into the slots pre-drilled in the pitot tube. The wires even have the crimp fittings and are labeled per the wiring diagram in the Piper Cherokee Service Manual. For any Piper Cherokee owners who might read this thread, In my service manual (published 1995) its on page 4F14. All wires H2A, H2B, and H2C are pre-installed. Wire H2A runs from the pitot circuit breaker to just under where the pitot switch would be installed. A plastic sleeve keeps the crimp fitting from shorting with the instrument panel chassis. Wire H2B runs across the bottom of the instrument panel and along then back behind the pilot side panel to the wire bundle under the back seats where it connects to wire H2C (the connection allows wing removal). Wire H2C runs out the left wing along with the Nav light and left tank fuel sender wires. If you remove the access panel by the pitot heater, you should see the end of H2C somewhere close to the pitot heat. It also has an insulator plastic sleeve secured over the crimp fitting. You may need a mirror or borescope to find it. While you have a borescope in there, double check to see if your pitot tube is pre-drilled for heater elements. The factory might not have been doing this in 1964. Also, the ends of H2A and H2B may be hiding within the wiring bundle under the switch panel. You might need to cut the zip ties/cord holding the wiring bundle together. I estimate an hour for the installation of the switch and two elements and who knows how long for the paperwork. If you want to see any pictures or see any additional details, just PM me.
 
When my heated pitot failed on my PA28-181, the IA bought a whole new replacement, mast and innards. Might have been much cheaper to get just the heat elements replaced; did not know it was available that way.
 
When my heated pitot failed on my PA28-181, the IA bought a whole new replacement, mast and innards. Might have been much cheaper to get just the heat elements replaced; did not know it was available that way.
Airparts of Lockhaven did an overhaul of my pitot a few years ago and the overhaul included new heating elements. That would be much cheaper than new.
 
For those of you who are an A&P (or have an A&P who is willing for you to do owner assisted work), you can purchase the individual heater elements from PMA products available directly from PMA Products Inc. or Aircraft Spruce. The Piper pitot head assembly (mast) has two heater elements. A shorter 3" long heater element in the front which is 70W and a longer 4" heater element in the back which is 100W. Both heater elements slide into 3/16" dia. deep bore holes. If your aircraft power is 12V, you want parts 464-357 and 464-356. If your aircraft power is 24V, you want parts 464-440 and 464-441. Each heater element is about $100 each, or $200 for the set. There is no adhesive. It's a friction fit. You might need a pair of plies to pull the old ones out if there is dirt or corrosion. Although I've seen heater elements still easily slide in and out of pitot head assemblies by hand that haven't been touched in over 50 years. The hardest part is probably removing the three screws holding the pitot head assembly to the underside of the wing. You may need to drill the heads off if badly corroded. Just watch that you don't accidently gouge the side of the pitot head assembly with the chuck on your drill when drilling the screw heads off (by angling the drill too close to the mast). I've seen a pitot head assembly damaged this way before. The entire job of replacing heater elements shouldn't cost much more than $300 to $350. $200 for parts and $100 for labor (30 minutes swapping parts including drilling old corroded screw heads, and 30 to 60 minutes for the paperwork).
 
Mach Diamond... thank you for an outstanding and informative post. I'd been searching the web for info on these pitot tube heater elements without much luck. I waded all the way down through this thread to find your diamond of a post. Part numbers, instructions, gotchas... can't thank you enough.
 
Mach Diamond... thank you for an outstanding and informative post. I'd been searching the web for info on these pitot tube heater elements without much luck. I waded all the way down through this thread to find your diamond of a post. Part numbers, instructions, gotchas... can't thank you enough.
So, did you replace yours? I am in a similar position. A used replacement mast is almost $600. Trying to convince my A&P that he can take this on.
 
The Piper pitot head assembly (mast) has two heater elements.
I am not a mechanic so pardon what may be a stupid question.
How would I know if both heater elements are working? I had previously (and obviously erroneously) thought it was one heater so if I turned it on while on the ground and walked over and felt heat that was a good enough check.
 
Just to compliment Mach Diamonds excellent description, there is one power wire (if installed) supplying both elements. The elements ground back through the structure. Remove the service panel nearest to the mast. Using a test meter with an amp clamp, test the amp load on the power wire with the pitot switch on to determine which element is not heating. If neither are drawing current use the volt function or test lamp at the connector to see if the circuit is alive. Price was as of 10/2021.

CA-464-356 - 70 watts/14 volts = 5 amps $100.00
CA-464-357 - 100 watts/14 volts = 7.14 amps $110.00

170 watts / 14 volts = 12.41 amps

The originals were set by using a center punch. Using a long drill bit of a smaller diameter to fit inside the element case allowed the drill to wedge sufficiently inside the stainless element case and the drill flukes with enough tension to extract the remaining element. Penetrating fluid I think was helpful.

After engine start an operational test is flipping the pitot switch and watching for a needle deflection on the panel amp meter.
 

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I had previously (and obviously erroneously) thought it was one heater so if I turned it on while on the ground and walked over and felt heat that was a good enough check.
That check is still legit even on the maintenance inspection side for most aircraft. While there are some heated probes that require a specific check they are the exception vs the norm. A simple troubleshooting method is to leave the pitot heat on for more than 90-120 seconds and see if you can touch the mast or hit with an IR temp probe. It should be untouchable or 150 deg + at that point. This will confirm both heating elements are working. Anything less and one or both elements are below spec. And while the elements can be changed it will depend on the condition of the pitot tube assembly in my experience.
 
After engine start an operational test is flipping the pitot switch and watching for a needle deflection on the panel amp meter.
I am going to have ask my mechanic to check both pitot elements. I can feel it gets warm to the touch so obviously at least one element works. I also question if my ammeter works properly. When I flip the pitot heat switch on, I only see a small movement barely noticeable. The ammeter does move with the pitot heat switch - just not as much as I would have thought to be reasonable. Gonna have my mechanic check that ammeter also.
 
So, did you replace yours? I am in a similar position. A used replacement mast is almost $600. Trying to convince my A&P that he can take this on.

Yes, replaced both elements in my pitot tube with the help of a friend. Old heating elements came out without too much fuss. New ones went in and made a little "clicking" sound when they seated. Wired them in parallel so that if one element fails the other will still get power.
 
Sounds easy enough. Thanks for the info!
 
I have a 1973 Piper Cherokee 140 and the wires have been there, along with the circuit breaker, for almost 50 years. The only hardware required for adding pitot heat in my Piper Cherokee then would be the switch and two heater elements that slide into the slots pre-drilled in the pitot tube. The wires even have the crimp fittings and are labeled per the wiring diagram in the Piper Cherokee Service Manual. For any Piper Cherokee owners who might read this thread, In my service manual (published 1995) its on page 4F14. All wires H2A, H2B, and H2C are pre-installed. Wire H2A runs from the pitot circuit breaker to just under where the pitot switch would be installed. A plastic sleeve keeps the crimp fitting from shorting with the instrument panel chassis. Wire H2B runs across the bottom of the instrument panel and along then back behind the pilot side panel to the wire bundle under the back seats where it connects to wire H2C (the connection allows wing removal). Wire H2C runs out the left wing along with the Nav light and left tank fuel sender wires. If you remove the access panel by the pitot heater, you should see the end of H2C somewhere close to the pitot heat. It also has an insulator plastic sleeve secured over the crimp fitting. You may need a mirror or borescope to find it. While you have a borescope in there, double check to see if your pitot tube is pre-drilled for heater elements. The factory might not have been doing this in 1964. Also, the ends of H2A and H2B may be hiding within the wiring bundle under the switch panel. You might need to cut the zip ties/cord holding the wiring bundle together. I estimate an hour for the installation of the switch and two elements and who knows how long for the paperwork. If you want to see any pictures or see any additional details, just PM me.
Howdy Mach Diamond, I have further questions if you could answer. Please and thank you.
 
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