[axlr8r]

I've installed and wired a Whelan microburst tail light on the bottom (rear) fairing of the rudder on my -8. Forgot to plan for this when I built the vertical stab, so now there is only a small opening at the bottom (between tabs) for the wire to run through into the fuse. My question is: 1. Would it be ok to elongate this opening sufficiently to allow passage of the wire and provide for a grommet, snap bushing or some other sort of protection and, 2. Or is it possible to drill a hole through both the VS803pp rear spar and VS808pp spar doubler without jepordizing the strength of the vertical stab spar assembly ??
Thanks in advance for any help.
Steve

 

[scsmith]

I did it like that

I remember thinking a long time about where to drill the hole before I finally did it. Now I have forgotten exactly, but it is just above the steel tailspring weldment attachment, so I didn't drill through that. Otherwise, its OK to drill a hole near the center of the fin spar and doubler that is big enough for a grommet, just stay away from other holes by at least a diameter (i.e. leave at least a diameter of meat between the holes). All the stresses in the fin spar and doubler are in the outer areas of the material, so you won't weaken the fin with a hole near the centerline of spar, in the midst of all the attach bolt holes, as long as you leave some meat around it for shear flow.

When you fit the rudder, you will need an elongated slot in the front of the rudder fairing to allow the rudder to swing without stretching or twisting the wires. I have a sort of service loop of excess wire resting in the bottom of the rudder fairing, but when the rudder swings, the motion has a very minimal effect on the wires.

 

[Bob Ellis]

Hi Steve

Take a look at DWG 78 top right hand corner - optional 5/16" hole for rudder light wires. I know that the view depicted is an 8A but the bolt holes for the bracket VS-410PP as shown on the rear view on DWG 73 are much further apart. As DWG 78 is for the 8/8A I take it that the wire hole position applies to both models and my inspector agrees.

I think that location ties in with Steve's suggestion/guidance and it fits neatly with the rudder fairing.

Regards

Bob
www.rv-8.co.uk
Loving the fibreglass phase ..... not

 

[axlr8r]

Aha !

Another problem solved Steve. I've already mounted the rudder and left an extra amount of wire in the bottom of the fairing for future service. I have also noticed that something would have to be done to allow the wire to have more freedom so it won't chafe as it goes through the vert stab. Your suggestion to elongate the hole in the bottom rudder fairing is perfect. Thanks so much Steve for that idea. I love this site and all the smarts available here.