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P-lead material
Posted: Wed Jun 04, 2008 10:32 pm
by Jr.CubBuilder
Ok I have a newbie to plane maintenance question here. Where do you get new wire for P-leads and what should it be?
My old P-leads have a mesh around them for RF insulation I assume, but they are looking really ratty and they also look like something somebody put together after a few to many beers. They work fine, but I'd like to reroute them and the insulation is so old I think it's about to crumble. Any suggestions?
Re: P-lead material
Posted: Wed Jun 04, 2008 10:59 pm
by GAHorn
Use 18 ga shielded wire (MIL-C-27500 ) with ring-terminals at the ends. About $1/ft from Aircraft Spruce 877-477-7823, Ground the shield at the magneto end only.
http://aircraftspruce.com/catalog/elpag ... ldwire.php
and
http://aircraftspruce.com/catalog/elpag ... lterms.php
Re: P-lead material
Posted: Thu Jun 05, 2008 9:06 pm
by Jr.CubBuilder
Thanks George.
Do you have any suggestions for reading on some of this stuff? I'm not a complete novice, but I would like to find some books that might be good reference and learning tools.
Like for example, why ground only at the magneto end? I'm pretty sure mine are grounded at both.
Re: P-lead material
Posted: Thu Jun 05, 2008 9:42 pm
by davevramp
If you have one end grounded it acts like an antenna and grounds all spikes If you ground both it is a transformer and there will be a current flow and there will be reflected resistance in the p lead ckt and could change the coil out put in theory.
Only ground one side
Re: P-lead material
Posted: Thu Jun 05, 2008 10:07 pm
by GAHorn
Jr.CubBuilder wrote:Thanks George.
Do you have any suggestions for reading on some of this stuff? I'm not a complete novice, but I would like to find some books that might be good reference and learning tools.
Like for example, why ground only at the magneto end? I'm pretty sure mine are grounded at both.
Do you have the Cessna 170 Electrical Systems Service Manual? Available from TIC170A
headquarters@cessna170.org