P-Leads, What a funny name that is.
Posted by Richard Bogert on
P-Leads, what a funny name that is. What the heck are they? Regardless what you think of the name, they are quite important to aircraft safety. In short, they are the wire between the magneto and the magneto switch. In most cases, they are as old as the airplane. No one gives them a thought and yet they take a beating and keep your engine ticking.
Two very bad things can happen if the p-lead fails. First, if the p-lead breaks, the mad will be hot. If the prop is turned by hand, it could start. I was lucky once and kept my hand and fingers. The second bad thing that can happen is, everything gets quiet up front and the pilot begins to sweat profusely. Been there, done that and got the T-Shirt.
There are some other less critical things that can also happen. Since a 6 cylinder engine delivers more than 14,000 150volt impulses to your p-leads every minute. That is 240 pulses a second. That can create some radio noise and it isn’t all that wonderful for your other electronic devices.
My advice to you is this. If your plane was built prior to 2004 and your p-leads are more than 20 years old, you should replace them. If the wire is cracked or it’s been spliced, replace them. If the shielding is broken away from the terminal nut on Bendix mags or the shielding is broken at the mag on Slick Mags, replace or repair the p-leads.
Bogert Aviation Inc. can custom make p-leads for just about any application. If you need to repair p-leads, BAI has FAA PMA terminal kits for Bendix Magnetos. We even have those hard to find terminal kits for radial and V-12 engines