Empennage – Sling TSI Build Log G-PTSI

Empennage Fairing

The empennage fairing did not fit too well. A large 4mm gap at the leading edge of the HS. It’s a nice snug fit on the VS, but not able to pull the fairing down to be flush with the HS. After discussing with the factory, I elected to add some flock filler along the fairing edges around the HS. (West System resin plus 403 filler). Drilling the 6mm holes in the fuselage for the rivnuts was a breathtaking moment. In the end, it all lined up very nicely. For easier inspection, I have decided to use flanged M4 hex button head bolts to fit.

17 June 2022 Ailerons / Controls / Elevator / Empennage / Flaps / Service Bulletins

Eyebolts – Sevice Bulletin

The factory has issued an SB 0020 on eyebolt types. Seems I have 25 out of 26 of the defective type 3 . All will need to be replaced! Spent 4 hours removing all eyebolts. The ones on the rudder pedals and inside the ailerons were harder than the others. Lucky for me I was able to do this at an early stage.

15 January 2022 Empennage / Horizontal Stabiliser

Horizontal Stabiliser

Extra countersinking in the forward spar is needed in my case, to accommodate the 8 extra dimples I made in the skin (top surface only). Many do not rivet locations. I needed to take great care to rivet. Awaiting for my main spar so paused for the moment. 5 Feb 2022 missing empennage parts arrived so I could finish the skeleton with Andrew’s assistance. Wed 9th Feb 2022 Spent a lot of time with laser level getting the HS absolutely straight (no twist). Level the table to start with. Various advice from other builders. partially cleco one side, level, then cleco the other side. Add more clecoes, check, turn, check, check again. Rivet from the centre outwards along the main spars, check, check, check all the way. Seems to be very hard to do accurately without a laser level. (9 hrs to do the HS alignment and skinning, but I am very happy with the result.

11 January 2022 Elevator / Empennage

Elevator

Started elevator, the instructions and Evans video are very clear. Note the 2 stainless steel rivets. Different rivet size on end ribs. 10 Feb 2022 Having got the HS absolutely straight proceeded with the elevator skins. Important notes. There are two floating ribs that need to be inserted the right way around. There are small pieces to strengthen the trim tab hinge. Smaller 6mm rivets are needed just on the right side at the thinnest point. The elevator composite tip on the right needed to be worked up with extra fibreglass. Add the trim servo inspection hatch mounting ring inside the elevator before skinning! Test fit to HS to check hinge alignment and elevator deflection. One hinge is is a bit stiff. Hard to attach on the bench. This will be hard with unsupported HS and Elevator. Deflection seems to be good and within specification in the POH (+30 Degrees). Earlier builders report having to remove some of the HS skin to achieve the required deflection.

10 January 2022 Empennage / Vertical Stabiliser

Vertical Stabiliser

The vertical stabiliser has some points to watch. Important to open up the M4 holes in the lower part of the vertical spar. Use some bolts to be sure they freely fit later on. I opened them up to 5 mm. The rivnuts are by design I think held behind the vertical channels. Looks a bit strange, but all holes do align and it seems that Evans Sling official build video advocates this assembly. (Rather than drilling clearance holes for the rivnut flange heads. (This may weaken the effectiveness of the rivnut). I set aside for the moment as I am missing rib 1. 26 Jan 2022 Avionics package arrived from the USA, did a fit of the RAMI 525 VOR antenna, carefully filing out the holes per KAI. With the grommets in place, it’s a tight fit. A bit of a bulge, let’s see how it goes with the skins. Note that the pins on the top of the antenna are connected to the antenna elements and could easily short over time with the doubler plate. I filed them flush and added some Teflon tape. 8 Feb 2022 LAA inspector signed off the empennage skeletons, so started skin riveting with the vertical stabiliser.

7 January 2022 Empennage / Priming

Priming

Did my first real priming today. My earlier test on the internal panels didn’t turn out too well. Streaky and poor coverage. Too cold and me never used an air spray gun before! Anyway, after a bit of learning on YouTube and an understanding of gun adjustments. I did some tests on the packing crate wood, I started on the real parts. Rudder and vertical stabiliser. It’s December and the outside temperature is 4 C, Aerowave 2001 the two-part primer I am using requires at least 15C and less than 80% humidity. I heated up the booth to 15C and carefully started. Took about an hour and 300 ml of Aerowave to do the first parts. Used a small HVLP gun at 29 PSI with a 1 mm nozzle and works quite well once I got the hang of the adjustments. For the second run of priming, I used 400 mL of Aerowave for the larger parts of the HS and elevator including skins internal surfaces only.

4 January 2022 Empennage

Let the dimpling begin

The empennage kit finally arrived (rudder, vertical stabiliser, horizontal stabiliser and elevator). Although some major parts missing, like the main spar! Anyway started by unpacking and removing plastic coverings. A good tip is to use a heat gun on the larger skin areas. It’s quite hard to remove the plastics in a cold workshop in December. Sort parts to main subunits – rudder, vertical stabiliser, horizontal stabiliser and elevator. Then to deburring mostly with a large drill bit or a small cordless drill with a countersink bit, a steel rule and a deburring tool for the larger holes. Purple Scotchbrite to finish off deburring. 2 days prep and deburring all parts of the empennage. Then my first dimpling. Having never done dimpling before, I read up around the topic. Philip Rueker’s blog has some good info. Important to note that Sling uses 120-degree dimple dies (not more standard 100 degrees). Two sizes of dimple dies are included in the kit. (Although since the materials are quite thin, the same size die is used for both skin and rib). The introduction KAI instructs that the holes to be dimpled are smaller (2.8 mm) and match drilled to 3.1 mm before a countersunk rivet is used. (I placed the Sling dies in my hand dimple tool). Andy kindly lent me his DRDT2. As my project is a quick build, I think I only have the empennage skins and possibly the aileron skins to dimple with the DRDT2. The rest of the ribs can be done with a hand dimple tool. The next step is to purple Scotchbright all internal surfaces, degrease and spray with Aerowave.