Top Skin Closeout and Engine Cowling Fitment
I received back my fuel pump assembly from Lockwood Aero, which was updated to comply with ASB 915 i-012. This fuel pump was the last thing I wanted to install before installing the top skin just aft of the firewall. The nuts that secure this pump assembly are on the inside of the firewall, and are easier to access without the top skin installed.
The top skin closes out the top of the fuselage between the firewall and the instrument panel. There are several important components beneath this top skin that are significantly more difficult to access once this skin is riveted on, so I’ve been holding off attaching this skin for a very long time. This includes the climate system air box & its associated hoses, a valve that opens/closes the flow of coolant fluid to the heater core, several cable pass-thrus on the firewall, and the Rotax ECU. The dash and windshield get installed on top of this top skin, so this is basically the last time I’ll ever be able to work in this area from above. I hope I never have to take out the ECU!
Next I began a finishing kit task: attaching the engine cowling! I have loosely put this cover on before, but now I had the task of fitting this properly to meet up with the fuselage skins.
The fiberglass cowling comes from the factory oversized, therefore it needs to be cut to the proper size. To figure out the cut line, I used the double-tape technique which is described in Evan Brunye’s Sling TSi build instruction video series (here’s the link).
To aid in keeping the cowling in place, I 3D-printed a set of clips that attach to the prop spinner plate. This clips keep the cowling centered and the required 5mm set back from the prop.
I bought a tool just for cutting the fiberglass, a Ryobi 3″ cutoff tool. I have a fairly large collection of Ryobi’s 18V One+ tools, and I’m impressed that they’ve remained on the same 18V battery platform for the last 25 years! Most of their tools are pretty good and this one is no exception: it has a brushless motor, a variable speed trigger, and it comes with 3 blades, including an abrasive cutting wheel with a nice thin kerf. It sliced through the fiberglass easily. Unfortunately it does create a bit of dust, so PPE is definitely required.
The tape method worked pretty well. I will spend a little more time with a sanding block to get the edges to line up perfectly with the skins of the fuselage, and then continue with installing the camloc fasteners.
