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Anyone want to offer guidance on best practice for replacing the P Leads from the firewall forward. The original hardware was#16 or 18 wire surrounded by a copper braid. The braid had a "shoe" on one end and appears to have been soldered to the back of the metal box that collects the leads where they penetrate the firewall.
Todd, this requires a mechanic's sign off, so rather than suggesting that you piece wires together (assuming that you are not an A&P) I suggest that you measure the length and then go to the website for Bogert Aviation.com
They make up P leads, and ask about the sheath (which is generic anyway and is there only for protection). Call them and discuss your needs. They also sell copper cable kits so if you have not yet replaced the aluminum cables on your aircraft you should do so and Bogert sells the kits.
Pat Barry
@patricbarry Thanks. I understand the requirements. I'm just interested to know what other A&P's have done. I've worked under an A&P for the last 16 years and have just passed my written exams.
Dear Todd, thanks for the information.
What have I seen? The metal cover is potted with phenolic. Shielding is merely for physical protection so use what is practical - I've seen copper, iron braid, lead braid, even plastic tube. The metal braid is soldered onto the metal cover, the idea being to protect the P lead. The wire gauge is not critical since it is a ground but you can beef it up if you want. I would prefer a heavier gauge wire simply because you don't want a wire than can vibrate its way to breaking in flight.
The reason why I suggest Bogert Aviation is simple - their kits are affordable and if you tell them the magneto, the aircraft, and the length, thy will make the lead for you, otherwise make it yourself. That still leaves the braid shielding and soldering it onto the metal cover - it's there for protection.
There's not a lot to add. Always follow AC43. Understand the principle of a P lead and why it is there, and build something that is practical, functional, and won't break. The original design accommodates all of those items.
Pat
@patricbarry Thanks Pat! This is exactly what I wanted an opinion on! I just couldn't make sense of the shielding for grounding's sake. It just didn't seem necessary for the purpose of a P Lead. But I also like to put things back in an original condition unless there's a compelling reason not to. I think a heavier gauge wire and something to resist abrasion exiting the box on the firewall will do nicely!
Happy New Year!
Todd
