While attempting to attached power and ground wires to the “Piper” Heated Pitot I’ve had for some time, one of the leads broke off one of the cartridge heaters. Both of my heaters were inserted a bit too much to get a grip on either of them.
At that time I did not realize that the heaters could possibly slide out of the head. A little research with the Van’s Air Force Group led me to the following:
It is possible to slide the heaters out with no or some minimal force.
Heating the head with a propane torch, allowing the heat to transfer thru the head does loosen up the cartridge, allowing it to be pulled out of the head. Some twisting of the head might help. It might be a good idea to remove the Pitot and Static fittings from the head to allow a needle nose pliers to get a grip on the cartridges. Be careful not to damage the leads coming out of the cartridges.
If it becomes necessary to drill out the cartridges, I suggest the following:
Use a 5/32” IRWIN Hammer Drill Bit to cut thru the ceramic center of the cartridge. This bit is about 6” long. A normal air drill works fine.
Follow up with a #13 Cobalt Aircraft Extension 6” long. This will clean out the hole and will leave a hole large enough for the cartridge. It may be necessary to follow up with a 3/32 Chucking Reamer. In my case the #13 drill made the hole just right. Needless to say, be careful that you do not make the hole deeper than it was.
As I got into this project, I realized that I needed 28V elements because my aircraft will have a 28V system. I was able to get these cartridges thru McFarlane. These cartridges are available at very reasonable prices and I did not have to order three of everything (some mixing and matching allowed) from the manufacturer.
McFarlane Aviation, Inc.
696 E. 1700 Road
Baldwin City KS 66006
CA464-440 PITOT HEATER ELEMENT 28V 70W
CA464-441 PITOT HEATER ELEMENT 28V 100W
The question remains as to how to hook up the cartridges. Piper runs them in parallel connected to a single source wire. With this arrangement it is not easy to notice a failure in one element until they both fail. A short in either element will cause both to fail Seems to me that two wires running to a split [double pole, single throw] switch, with separate fuses/breakers for each element, would make a more logical arrangement.