Horizontal Stabilizer 8-9-6 to 8-9-8

To get the remaining horizontal stabilizer parts ready for priming, I had to debur all holes, dimple most of them and countersink a lot of them along the stringers and spars.

I began by deburring the rib holes, and dimpling the 3/32" holes along the rib flanges (except for those that are for fairing attachment or that sit inside the stringers/spars). This was easily accomplished using the pneumatic squeezer.

Ribs and stringer web deburred, dimpled as needed and ready for priming

I then proceeded to start deburring the holes in the skins. No issues here except that it took a while with almost 1000 holes to be deburred inside and out. Next I dimpled all the skin holes (except empennage fairing holes) using the DRDT-2. I was able to dimple all the holes with just the DRDT-2 and this tool makes the process so easy.

Dimpling using the DRDT-2 

Dimpling the skin holes with the skins in this orientation took a little extra care as the dimple die pilot was now lowered in from above, but it did enable me to get a gravity assist in holding the skins apart so that I could easily dimple the holes nearest the bend.

Both stabilizer skins dimpled and ready for priming

Now it was time to start countersinking. I began by setting up the countersink cage in my drill press so that I could securely position the stringers as I countersunk the #40 holes. A piece of 2x6 with a hole drilled near the edge to accommodate the countersink pilot worked really well here.

Countersinking the #40 holes in the stringers

I did have to be careful while countersinking this way to make sure the countersink pilot went into the hole without any resistance before starting up the drill. I found that as I moved along the stringer, there were some holes that were not perfectly in line with others, and if the pilot went into the hole with some resistance, that caused the hole to elongate ever so slightly even though the countersunk part looked fine.

All stringer #40 holes countersunk, and stringers are ready for priming

I have now completed all preparation of horizontal stabilizer parts that require priming. Once these parts are primed, I'll finish prep work on the spars (deburring holes and countersinking) while the primed parts cure.

Remaining unprimed stabilizer parts labeled and ready to etch and prime

Build Hints

  • When countersinking using a drill press, ensure that the countersink pilot enters the hole with no resistance prior to drilling, otherwise you risk elongating the hole as the countersink is cut.
Time Taken:     6.4 hours
Dates:                September 18 - September 22 2022

Horizontal Stabilizer Total Time:   46.0 hours
RV-10 Build Total Time:                  122.0 hours

Priming Total Time:                     10.8 hours (not included in build time totals)