Sling TSi Build Day 9: Engine Cowl Install (916iS) (AU)

#SlingTSi #EngineCowlInstall #Rotax916iS

In Part 11 of our Sling TSi builders assist series, we focus on the engine cowling installation, showing exactly how our molded fiberglass upper and lower cowls fit over the Rotax 916iS engine. I knew that the cowls would be precise and take time; this video was edited to show the reality of fitting, checking, and refitting—to give you a genuine insight into the build process. Ultimately, it takes a lot of patience to get everything aligned and sealed correctly. With the help of the Global Aviation Products build-assist team at Heck Field (Gold Coast, Australia), you’ll see step-by-step how to prepare and fit each cowling piece for a perfect, airtight enclosure—setting the stage for our first engine run and cooling tests in the future.

Episode Overview & Why You Should Watch

In Part 10, we unveiled our DUC Propeller and completed the Rotax 916iS integration. Now, Part 10 is all about enclosing the engine inside the Sling’s fiberglass cowling, which is crucial for cooling, protection, and aerodynamics. According to the Sling manual, the cowling consists of:
• Upper Fiberglass Cowling – houses the engine top, air-filter plenum, and radiator inlets
• Lower Fiberglass Cowling – supports the oil radiator, oil reservoir, and provides underside outflow by the firewall
• Inspection Panels – On the upper cowl, each secured by fasteners

The cowling design channels air from the right-side intake into the air filter, through to the engine, and then over the cylinders via the front nose intakes. Coolant and oil radiators draw additional cooling air, and hot air exits underneath near the firewall. In this episode, we demonstrate how to:
• Unbox & Inspect Cowls: Identify molded cowling pieces, locate inspection panels, and verify air-intake openings.
• Fit Upper Cowling: Align the upper panel around the firewall and engine mounts; trim around the right-side air inlet so the air filter gets unobstructed airflow.
• Install Lower Cowling & Baffles: Mate lower cowling sections, position baffles to direct airflow through the oil and coolant radiators, and confirm that the firewall outflow area is clear of obstructions.
• Build-Assist Tips from Global Aviation: Quick pointers on avoiding common misalignments when fitting cowls on a Sling TSi with Rotax 916iS.

Whether you’re building a Sling TSi yourself or are just curious how the cowling houses all critical components (engine, filter, coolant radiator, oil radiator, and oil reservoir), this video is packed with practical tips and detailed visuals to help you get your cowling fitted correctly, even if it means showing the trial-and-error process.

In This Episode, You’ll See:
0:00 Introduction & Part 9 Recap
1:13 Cowling Unboxing & Inspection
• Identifying upper (1) and lower (2) molded fiberglass cowling panels.
12:20 Engine Muffler and Exhaust Fitting prior to lower cowl install
13:05 Upper/lower Cowl Alignment & Trim
• Preparation tips & helpful knowledge advice by Errol
15:08 Upper Cowl Alignment & Trim
• Aligning around the right-side alternator
• Forming and aligning profile of cowl
• Alignment / Distance to DUC Propellor
24:40 Lower Cowl & Baffle Installation
• Mating lower cowling halves to the upper pieces.
• Insights on avoiding misalignments and ensuring airtight fitment.
31:55 End of Week 2 de-brief

Resources & Links
Sling TSi Kits & Info (Official Sling Aircraft):
https://www.slingaircraft.com/aircraf...

Build Assist in Australia (Global Aviation Products):
https://gapaero.com/

Rotax 916iS Engine Details & Specs:
https://flyrotax.com/engines/rotax-91...

DUC Propellers (Our Prop Manufacturer):
https://www.duc-helices.com/

If you’re planning a Sling TSi build or have questions about cowling fitment, drop a comment below—happy to help with any details, from inspection-panel positioning to airflow setup.

Thank You & Call to Action

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Thank you for watching and supporting our Sling TSi build—see you in Part 11 as we bring this Aussie-built bird one step closer to flight! ✈️