Hey Cessna Pitot users....

[vmirv8bldr]

I acquired a used Cessna pitot and modified it to fit the Gretz mounting kit. (Modifiecations were simply removing material with a file until it fit far enough to align the screw holes.)

At any rate, this is a heated pitot off of a 150. The electrical part is simple enough to figure out. But the pitot tubing part is causing me concern.

The aluminum pitot itself has a female threaded hole and is quite large, between a -4 and -6 size. Additionally, the tube arrived at my door with a nylon or plastic male - male fitting in the hole.

Questions:
1. Is this thing going to melt when heat is on? (I could test it, but then would have to clean melted stuff out of the tube.)

2. Should I replace this nylon or plastic fitting with an aluminum fitting, and if so, any idea what size / type fitting?

I tend to think that ideally I would want a non heat-conductive junction as close to the pitot tube as possible, to help retain heat in the tube itself rather than spreading through instrument tubing.

Thanks,

Thanks

[Ironflight]

B.P.

I can't tell you for sure about the Cessna pitot, but I used a Piper blade-style heated pitot that I had been carrying around in a box of parts for years. I wasn't sure how hot it would get, and had the same question you did about nylon or metal fittings - it had a barbed aluminum fitting screwed in. I slipped a nylon tube on, hooked it up to my power supply, and watched the nylon tube melt right off.....

I installed using aluminum tubing!!

Paul

[mburch]

After I scorched my hand testing out my AN5812-clone pitot tube, I decided to run aluminum all the way to the wing root and make the transition to nylon there. Pretty easy and indestructible.

mcb

[DGlaeser]

I also have a Cessna pitot which came with a nylon fitting as well. The heating element is in the round part of course, and in my simple and fairly short test (with the fitting removed), the 'vertical' part of the unit did not warm up very much. Based on that, I'm planning to use the nylon fitting and currently have nylon tubing run to it. Whenever I've preflight tested Cessna pitot heat on A/C I've flown, I've only noticed the part near the opeining heating up much (which is what you'd expect...).
Based on Paul's report, I will do a longer test in the near future...
I believe the nylon fitting is a -5 (5/16) thread if memory serves (a chancy proposition).

[Jamie]

My Cessna pitot came off a 172, but it's exactly as you describe.

The AN fitting part # I used is: AN816-4-4D. Took me several tries to get it right.

You can go here for more info. Note that in the picture the pipe threads are not fully inserted. Also, I have no idea why they drilled the hole in the top of the hole at an angle, but I figured it may be some aerodynamic voodoo or something.

BTW: Mine also came with nylon fittings, so it's apparantly what Cessna uses and I wouldn't think there would be a problem with it.

[Kevin Horton]

Does anyone know if Cessna uses different part number heated pitot tubes on the various models? The amount of heat extracted by the air passing by will vary with airspeed, and I'm wondering if they might have pitot tubes with different wattage heaters for the various model Cessnas. If so, I would want one from a Cessna that cruises at RV speeds, to be sure to be getting enough heat.

[Jamie]

In a perfect world there should be no air passing 'through' the pitot. The line should only pressurize and maintain a static pressure. If the air is going through, you have a leak somewhere in your pitot system.

[Norman CYYJ]

Many pitot tubes allow the air to pass thru and the water.

[Jamie]

Oh yeah, you're right. Out through a little hole in the aft end usually. The line though should remain pressurized.

[Captain_John]

BTW, I just test fired the Falcon unit. It gets CRANKIN hot real quick. Not all the way up to the fitting, but almost.

I arrived at the decision to install a 6" slice of AL tube before transitioning to the plastic stuff.

I figger that is prudent.

CJ