More than 10 years ago, I decided to install a bullet camera at the top of the vertical stabilizer -- part of a multi-camera video system I was going to install. Since the VS was already closed up and riveted at that point, I had to figure out to run the camera wire (!) from the top of the tail down into the fuselage. I'd managed to insert a 1/4" ID thick plastic tube down into the leading edge, through the rib holes. Then, I'd bonded it at the top with flox, and at the bottom with E-6000 glue. It held pretty well at each end, but it had no support in the middle. At the time, I didn't give it much thought, and in the last decade, I'd completely forgotten about it. In fact, I'd long ago removed the camera wire after GoPro cameras became more popular and easier to use than hard-wired cameras.
The plastic tube's presence reemerged last week when my friend Jim and I were towing the airplane down the taxiway to the paint shop. I heard and felt a light "tapping" noise coming from inside the VS as the plane went over the cracks. Later that evening, after thinking about it, I figured out what it probably was -- the plastic wiring tube, slapping the inside of the skin. I was immediately ashamed of this halfass installation from the past, and decided to try to remedy it by removing the tube.
Today, I took a bin full of tools over to the paint shop and began work. I used a Dremel tool with various ball-end and cylindrical grinding tools to remove the flox from around (and in) the upper end of the tube, which went pretty well. Next, I tried pulling the tube upwards with a pair of needle-nose pliers, but the tube only stretched. I inserted a curved dental took under the lip of the VS and discovered that I could actually push inward on the bottom end of the tube, but not enough to get it to release. Finally Jim suggested using a heat gun to soften the glue and the tube, and this worked really well. The tube broke free and came out after a few minutes of heating.
Now I'll have to fill the hole with caulk or JB-Weld to prevent moisture from getting inside the VS.
Glad we got rid of that problem! It would have been really annoying.