Engine Wiring Harness & Misc Mx Questions

[d0tnet]

I would like to 'clean up' the appearance under the cowl while also being proactive at replacing life limited items.  I have an A&P/IA buddy that is going to do owner assist on these items.

A few requests for input from fellow Mooniancs -

1. Does anyone have photos of what good looks like as it relates to engine wire management?  I was looking at the Air Boss ignition harness for reference and would like to have a more modern and colored coordinated look inside the engine compartment.  Any recommended sources for a wiring harness available in different colors?

2. My scat tubing for cabin heat keeps getting damaged by the cowl flap actuator bar.  Any photos of the proper routing would be great; it is currently zip tied to the number 3 induction tube and then routes up to the cabin heat entrance.  The cowl flap actuator digs into the scat hose every time it is opened/closed; not a good situation.

3. Should a fuel hose be strapped to the cowl actuator bar?  I just noticed something of concern while looking at the scat hose, there is a dual zip tie setup securing the main fuel line coming from the firewall to the actuator bar.  As such, the line moves every time the cowl flaps as actuated.   I would have imagined the tubular engine mount braces would have been a lot more suitable place to secure a fuel line, since it won't move. EDIT: Picture attached.

 

Edited March 2, 2016 by d0tnet

[Yetti]

2.  If you have a open stand off on the firewall, there should be a 2" or so Adel clamp that holds the hose.   Should work if cut to the right length.

3.  Do you have a fuel flow transducer.  Looks like they stuffed the extra hose up there.   Hose can be shortened and routed better.   Adel clamps help

[kortopates]

I can't follow the photo from my phone but I'll add to the above that nothing should be tied to something moving unless it's moving with it. Nor should anything be allowed to rub up again something; that leads to chaffing as you well know and should be corrected.

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[Guest]

I'd add that Ty raps should also not be used, other than to secure wire bundles, but never to steel tubes.  Also looks like the intake drain line is automotive fuel line not Mil H 6000 hose.

Clarence

[Yooper Rocketman]

I was watching a judge at Air Adventure a few years ago and he said a deduct in judging aircraft (and according to him an FAA issue too) is tie wraps on steel tubing like engine mounts.  Clarence is correct.  If you attach something to a steel tube, do it with an insulated Adel clamp.

MANY years ago when I worked for an over-the-road trucking firm, I saw an instance where a light steel tube that was a "blow by vent" for the valve cover extended down near the bottom of the engine and had rubbed on the flange of the engine block long enough to actually make a huge gouge in the flange for the oil pan.  No one could believe that light wall tube could have rubbed a large gouge in the cast iron block before wearing off the end of the tube.  Tie wraps will do the same to your engine mount.

Tom

 

[kortopates]

That is an excellent point about the engine mount. Not only will a ty-wrap chafe it but chaffing is greatly accelerated in the engine environment unlike other areas of the plane because the engine is vibrating. When an Adel clamp won't work for clearance reasons another acceptable way to use a try-wrap is to place a section of hose entirely around the steel tube so that the hose is between the tube and try-wrap. Speaking of this, the factory does something very similar with the brake lines on the tubes of the gear were clearance is tight. but rather than using hose they use something more akin to tape.

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[Yetti]

Friction tape on the brake lines with steel clamps