Fastening tube & wires in engine compartment

How much slack is needed between engine and engine mount when fastening down tubing and wiring?

I was just looking at my systems routing and I think I have over constrained fuel lines and large wire cables. I've become more aware that the engine will shake independent of the engine mount and that I shouldn't use adel clamps everywhere to tie stuff down. Right?

What tips do you have for securing wires and tubing in the engine compartment?

Should the fuel ine that comes out of the fuselage be secured to the mount before it attaches to pump?

Should starter cable attach to mount right next to where it attaches to the engine?

Thanks

It depends on how you route things and where they're going. The front of the engine moves much more than the rear. Most things are routed to the rear (oil lines, electronic ignition, temp sender wiring, etc.) and only need to be mildly slack between where they meet the airframe and the engine. The exception on my aircraft is the mixture, throttle, and alt-air controls, which go to the throttle body and FAB and see more movement, so they require more slack. I don't have exact measurements for you but maybe others will chime in.

Slack

If you allow enough slack and clearence for the engine to rotate plus or minus 3/4" that should be plenty. Adels are good. Cables wires and hoses should be firmly secured to firewall, engine mount and engine, the slack needs to be where the cables/controls/ hoses bridge the gap between mount and engine. The fuel supply hose is not normally secured between the the firewall fitting and engine driven fuel pump. Photos of what you are trying to do would help.

Don Broussard
RV9 Rebuild in Progress
57 Pacer

Hi Steve,

You ask some really good questions - one that I wish others asked before charging into a FWF build without experience. Doing TC visits, I have found fuel lines secured so tight that they would have ripped the ends out at the first hit of the starter - mostly because the person setting them up had no FWF experience and didn't ask.

Unfortunately, this is probably not something that you can be educated on simply by folks answering questions on a forum - which is why the Tech Counselor program can be so valuable. Get someone with experience to drop by and have a look at what you've done, and either say "great job!" Or maybe "you could improve this a little bit..."

Don't build in a vacuum - get some other eyes on the project and enjoy some company.

And having everything tight as a drum is NOT a good idea - there are places you need loops and slack to allow things to move - and other places you shouldn't.

Paul

look at FWF on other aircraft too

Paul is of course right. If you can look at how others have done it in addition to getting some experts to look at yours it will help. Keep in mind that there are flying RVs (and other aircraft) that don't do it right.

I learned a lot as well by looking at the RV-14 plans, and the virtual walkaround of the FWF - this is a really cool thing that Van's has done.

http://www.vansaircraft.com/images/RV-14/RV-14_360/RV-14.html

Keep in mind it takes some time to load before you can move it around.

The FWF plans for the RV-14 make it even clearer, and helped me even tho I'm building an RV-8. I'm really happy with how my FWF turned out - very clean and I believe very safe.