Tail Cone 10-15-3 to 10-16-5, Rudder Cable Fairings

I continued on with the tail cone by deburring all parts, starting with small parts. I had already deburred all edges and a fair number of holes in previous work sessions, so the majority of deburring now was just the remaining holes. It still took a while!

Using the saw horses to support the skins while deburring the remaining holes

The square aluminum tubes add additional support to prevent skin sagging

Next I drilled the 11/16" hole on the aft bottom skin for the tie down with the drill press.

Drilling the aft tailcone skin on the drill press with a unibit

Tie down hole done!

I cut off the previously marked triangular portion at the front of the right side skin using a dremel with a cutoff wheel for the initial rough cut. I then used a vixen file to clean the cut to the marked line, and needle files and a scotchbrite pad to finish the cut.

Using clamps to hold the right skin while cutting off the triangular portion with a dremel and cutoff wheel

Triangular piece removed and cut finished with various files

Next, I decide to work on the rudder cable fairings. I had purchased rudder cable fairing attachments from Aircraft Spruce and these needed to be finished to fit the openings in the side skins for the rudder cables.

I began by straightening the web of the fairings as they were a little out of shape from the metal being bent during forming. Straightening was easily done with the hand seamer.

On each side skin I plan to use 2 fairings back-to-back, and attach them from the inside of the skins to give a more finished look. After figuring out the required positioning to allow the MS20668-4 (1/2" x 3/16" head) eye end on the rudder cables to pass through, I marked the positions of all rivet holes trying to space them as best I could to maintain required edge distances. Two of the fairings will need to have part of the web cut off to avoid interference with the F-1011 bulkhead, so I marked those cut lines as well.

Rudder cable fairings straightened and marked for rivet holes

I also realized that having the fairings back to back will require a spacer on the skin side to avoid deforming the skin when I go to rivet the fairings in place. I marked the spacer dimensions on a piece of 0.032" sheet from the empennage trim kit. These are cut out, and match drilled to the fairings later.

Spacers marked to fit between fairing and skin

Before drilling or cutting the fairings, I decided to verify my measurements by ordering an MS20668-4 eye end fitting from Amazon to make sure it fits through the planned opening. While I wait for this to arrive, I decided to begin dimpling of the parts. Continuing on page 10-15, I dimpled and countersunk the F-1006D, F-1012, and associated parts.

I did have to use a narrow female dimple die in a few places, most notable at the narrow end of the Rudder Stop Skin Stiffeners. Here the hole is very close to the bend in the stiffener, and even with the narrow dimple die, the bend was pushed apart slightly while dimpling. I was able to bend it back with minimal distortion, but it is something to be aware of for any future builders reading this. Narrow dimple dies definitely help in cases such as this, and I have both for 3/32" and 1/8" dimples.

Rudder stop brace and tie down bar countersunk, and Rudder Stop Skin Stiffeners dimpled

I then continued with dimpling the two cover plates, all flanges of the bulkhead and frames, and the J-channel skin stiffeners. All these were easily done with the pneumatic squeezer, except for

the flanges of the F-1012B bulkhead. Due to the angles of the flanges, the yoke would not fit and I resorted to using the vice grip dimpler. The dimples aren't quite as crisp, but they are adequate for holding an AN426 rivet flush
a few dimples on the bellcrank ribs where the lightning hole location interfered with the yoke. I used the DRDT-2 to dimple those

I had a slight issue dimpling the narrower J-channel stiffener that I had encountered in a previous post. The reason was that the holes on the narrower part were somewhat closer to the bend in the stiffener, and the yoke would push the bend apart as the dimple was forming. I noticed that by holding the yoke along the stiffener, rather than perpendicular to it, I was able to dimple these with minimal to no distortion.

In the F-1006 bulkhead, which the plans say not to dimple, I decided instead to dimple the few holes in the tabs that sit behind the stiffeners. These holes will be dimpled later anyway, and I figured that when I cleco the F-1006 bulkhead into the finished tail cone, it will sit better against the stiffeners.