P-mag ignition lead routing.

[Desert Rat]

When I started looking into this, it seemed like there were a couple of instances where these leads were exactly the wrong length; Too long for the shortest routing without leaving a big loop flopping around, but too short to take a longer but more out of the way path.

It took me a long time to figure out something that made sense here. One of my big goals was to try and keep wires out from under the oil filter but even so, I ended up having to run two under there, given the lead lengths provided by Emag.

On the top of the engine I also wanted to avoid piggybacking adel clamps off the ones that support the fuel injector lines. Cessna does that exact thing in 3 different locations on the 172 but it just seems like something to be avoided if possible.

When I replace this harness in 500 hours or so, I think I'll likely hand fabricate specific lengths to see if I can get this a bit higher and tighter, but until then this seems like a nice neat installation that won't give any trouble.

When I was scratching my head trying to figure this out. I did a lot of googling and looking at pictures on VAF and build logs and what not. I really didn't find much that was helpful to my specific situation.

So, I'm posting these pictures here for critique and comment, but also so that people can find them in future searches. Hopefully they might help out some future builder who's wondering how the heck to route this stuff. There are also more on my build log entry from todays date.

I'm not saying this is the only way to do this, or even the best way, but it seems like it will work well in my very specific situation; RV7 with an IO390, dual P-mags, modified RV14 baffles, and an inverted firewall mounted oil cooler.

As always, questions or comments are always welcome.

 

[rmarshall234]

Beautiful work. IMO, routing and stand-offs is one of the most challenging and critical parts of a build. Nice attention to detail.

Questions? Just one and it only came up on the final pic…does the oil filter share the same safety wire as that oil sending unit (?) or just a common connecting point? We blew up an engine at Reno once due to the former.

 

[Desert Rat]

…does the oil filter share the same safety wire as that oil sending unit (?) or just a common connecting point? We blew up an engine at Reno once due to the former.

Ha!, sharp eye for detail there

Instead of safety wire, Lycoming now ships engines with fancy safety cable with swaged ends. It came from them with the filter already safetied via that method and that crimped cable end blocks the hole in the cast tab on the engine block so you can't get a second piece of wire through it.

I just looped the wire around the tab and cinched it down so that the resulting loop is small enough it cant slip off because of the swaged end fitting of the cable tha'ts coming from the oil filter.

At the first filter change I'll be cutting that cable off and going back with regular safety wire. Once I get rid of the crimped on fitting butting up against that hole I'll have room to loop two separate pieced of wire at through that same hole, one to the filter nut and one to the sender.

 

[Dad's RV-10]

...Lycoming now ships engines with fancy safety cable with swaged ends...

Safe-T-Cable

 

[Desert Rat]

yeah, thats it. All the manufacturers use it now because it's fast and pretty much bulletproof. But you'll note that the manual gun for .032 equivalent is $450 and if you want a pneumatic one, it can be yours for the low, low price of only $1,500.

That makes a ton of sense for a manufacturer, where it doesn't take long to recoup that in saved labor time, but kinda hard for me to justify here in my garage

 

[dmattmul]

DMC Tools

Ha!, sharp eye for detail there

Instead of safety wire, Lycoming now ships engines with fancy safety cable with swaged ends. It came from them with the filter already safetied via that method and that crimped cable end blocks the hole in the cast tab on the engine block so you can't get a second piece of wire through it.

I just looped the wire around the tab and cinched it down so that the resulting loop is small enough it cant slip off because of the swaged end fitting of the cable tha'ts coming from the oil filter.

At the first filter change I'll be cutting that cable off and going back with regular safety wire. Once I get rid of the crimped on fitting butting up against that hole I'll have room to loop two separate pieced of wire at through that same hole, one to the filter nut and one to the sender.

Go to the dark side and purchase the "fancy safety tie" system that DMC produces (swaged ends) and never have (Almost never) a safety wire tie sticking you. Alot less blood events. Greatly simplifies safety wiring a prop.

Less blood, priceless.

 

[Taltruda]

Just skip saftey wiring oil filters all together.. Robinson approved deleting saftey wire on their R44s.. if a rattling, shaking helicopter doesn’t need it.. I think I’ll be ok. To the guy who blew a motor at reno due to saftey wire.. what happened?

 

[rmarshall234]

To the guy who blew a motor at reno due to saftey wire.. what happened?

Long story short….
Continental O-200, no convenient place to safety the oil pressure relief valve (acorn nut) and oil filter which is an add-on. First crew member safeties them to another, second crew member does an oil change sometime later and safeties the new filter elsewhere. During a race the OP relief valves works its way loose and dumps all the oil overboard throwing a connecting rod thru the top of the case.
Lesson learned…..
Don’t safety two components together, it’s a bad practice.