Dissection of the old engine to examine the cause of in-flight engine failure. Probable cause: failed con-rod bushing.
Purchased and picked up a zero hour Rotax 912 A3 engine from 2001 (conserved) including oil tank, radiator, muffler, and some of the hoses. Price: 10.500 EUR.
Bought and watched two instructional videos from homebuilthelp.com: -"Rotax 912 Installation Tips & Techniques" - "Building your Zenith CH701 912S Engine Installation"
Engine mount, oil cooler assy. fuel pump assy., choke assy., oil tank mount, cooling system, and throttle assy. Price: 3.000 USD + shipping and Danish import VAT (25%)
Oil cooler fittings, fuel line splitter hub (between fuel pump and carbs, for output to carbs and fuel pres. gauge) and fire sleeves ordered from pilot-shop-24.de. Price: around 400 EUR incl. VAT and shipping. On newer Rotax 912 UL engines the fuel splitter is already installed.
Signed up for the paid rotax-owner membership for 29 USD/year. Started checking for outstanding SB's.
3 hours: Made an inventory of the parts recieved from Rans, and sorted them by assembly. Added assembly drawings, parts list, and relevant manual pages to the floor layout. No parts were missing thanks to the professionalism of Rans. Amazing to have this upgrade possibility still on such an old airframe.
3 hours: Made sure the Rans was sitting level on the floor, then added stings with weights from tail and nose, to indicate the longitudinal centerline. Test mounted the engine mount using the old nuts to verify mount centerline right offset (at the prop location) of 1/8-1/4 inches relative to the aircraft centerline. (No washers needed to adjust angle). Then attached the mount using the new lockluts.
4 hours: Mounted the oil reservoir to the engine mount. Attached the oil cooler to the right of the prop gear box (When looking from the front).
2 hours: Found out that the old radiator from the 582 setup could be used, so it was an easy task to re-route coolant hoses to the new engine. Fitted two preshaped hoses between the cylinders to clear the engine mount. These hoses were supplied by Rans. Mounted coolant overflow reservoir to the firewall.
6 hours: Found the best location for the muffler between the rear of the engine and the wirewall - clear of both the starter and generator. Designed a placeholder exhaust pipe from plastic plumbing fittings. Made sure there is sufficient clearence to engine parts and cowling. Next step in the exhaust installation will be to cut the real 1 1/4 inch exhaust tubes and weld them.
4 hours: Drilled holes in the cockpit center panel for throttle and choke. Mounted a firewall reinforcement for the cables. Trimmed bowden cables and wires, and connected to the carbs.
Ordered a 68" two-blade Warp Drive propeller with HPL hub, spinner and a 1 1/2 inch prop spacer. This prop is approved as per the Rans S6 kennblatt (II,7). It should arrive within about a month or so.
Ordered and received engine fluids (AeroShell 4-plus oil, BASF 48G coolant) and monitoring gauges from suppliers across Europe. Rotax 912 RPM indicator, fuel pressure, oil pressure, oil temperature, and 2 x water temperature.
8 hours: Mounted a new RPM indicator, oil temp. and pressure gauges, volt meter, and fuel pressure. Routed a 6mm fuel line through the firewall to be connected after the fuel pump. Connected sender pins to measuring points on the engine. (Oil temp and oil pressure sender cables with heat protection)
8 hours: Cut two donut-shaped exhaust pipe and streight tube into many pieces to allow routing from the cylinders to the muffler.
2 hours: Mounted two plastic finishing panels behind the seat. The lower being the baggage compartment.
6 hours: Unmounted the old, scratched and cracked windshield. Traced it digitally, and laser cut a new one from a 2500 x 1250 x 2 mm piece of Lexan. The original windshield was 1,5 mm but the supplier did not have that thickness. Time will tell if the added thickness will result in more stress and hence cracking in the corners. The 2mm is 700 grams heavier than the 1,5 mm. Cutting file here
3 hours: Did an estimate of the weight and balance of the Rans when the conversion is complete. First, all remaining parts not yet attached were put in their place (exhaust, windshield, oil, coolant etc.) Cheched the Rans was sitting level, and put a scale under each wheel (raising the other two wheel accordingly so it remained level). See the C.G curve above. Nose wheel: 90 kg Left main gear: 90,5 kg Right main gear: 96,5 kg. (heavier because the battery sits in the right side) Total: 277 kg. Based on this preliminary WB, the Rans will be close to nose heavy in the worst-case-scenarios. (Correct fuel tank and passenger arm now added). NOTE: this estimate may change with the final weigh-in. If it is still close to nose heavy, the battery needs to go further back in the fuselage.
6 hours: Mounted the new windshield, coaming panel, and two aluminium side plates to shield of view to the mess of wires and tubes on the back of the instrument panel.
6 hours: Converted the engine from Rotax 912 A3 to A4: Opened the gearbox. Removed the governor unit with oil supply line, plugged the oil feed at the oil pump, and installed cover plates and shims inside the gearbox to prevent oil leaks from the gearbox and prop flange. Cleaned off old sealant, and added new before closing the gearbox again.
1 hour: Picked up the exhaust pipes and muffler from the welder and assembled it. A perfect fit with no adjustments needed. Secured the exhaust system with exhaust springs.
3 hours:Installed fuel lines: 8mm line from fuel filter to fuel pump. 6mm from fuel pump to distributor. 6mm lines from distributor to carbs, fuel pressure gauge, and fuel return line. The fuel return prevents vapor lock.
1 hour: Installed the two-blade 68" Warp Drive prop with propspacer and faceplate. Adjusted pitch to 16 degrees initially. This will have to be less, but I do not want to risk over-revving the engine.
2 hours: Filled the oil tank with two liters of oil. Added 1 psi of air pressure to the oil tank, and rotated the prop to draw oil through the system, until oil came out of the oil tank return line. Added oil throughout to prevent air from being drawn into the system. Then crancked the engine to verify an oil pressure of 2 bar.
2 hours: Filled appx. 15 liters of fresh fuel in the tanks. Cranked the engine for 15 seconds with fuel and mags off to build oil pressure up to 2 bar. Then mags on, fuel valve open, and the engine started! Oil pressure was good, and the generator charging. Success!
3 hours: Suddently while doing carb balancing, the starter died after 2 sec of cranking. When turning the key again, there was no voltage reading. The voltage as measured on the battery poles was 13v. Strange. When turning battery on again after 10 mins, voltage reading was 13, but when attemting a start went back to zero. It turned out the battery had suddently collapsed, so it was a great luch that the new 1,4kg LiFePo starter battery with integrated balancer had just arrived. It was installed, works, and it cranks the engine easy. Specs: LiFeEnergy 10000, 12V 10Ah, max. charging current 40A, max discharge current 280A (continous), 480 (puls)
4 hours: Using a set of two pneumatic gauges, the throttle cable ferrules were adjusted to deliver the same amount of air/fuel in idle, and to check the mixture in the two manifolds is the same at high RPM's. The Rans was safely tethered throughout the calibration.
1 hour: Opened the valve covers, and pressed down on the rocker arms, to see if they could be moved. If so, it is a sign of a bad oil purge. They were all firm so all ok. replaced the valve cover o-rings.
1 hour: Installed safety wire on exhaust springs and throttle cables.
Hopefully this tasks overview may serve as a guide if you are considering installing a Rotax 912 in an airframe. The entries above document the tasks highlighted in manuals and instruction videos. Many tasks are omitted in the list as they would probably be irrelevant in another context. I.e. they pertain to this specific airframe with the condition it is in, and the stock of old / new parts I had for this conversion. estimated 30 hours: In order to illustrate what these tasks were, here is an incomplete list: - cleaned and oiled air filters - made calculations to ensure the electrical load does not exceed 15A (recommended max.) - bought and installed a thick wire to ground the engine block - vacuum cleaned the cockpit from all the metal chips created when mounting instruments etc. - spend at least an hour total looking for lost nuts and screw on the cockpit and hangar floor. Even in the grass outside the hangar! - spend a long time troubleshooting a non-functioning oil temp gauge, before realising the cable was faulty and "contaminated" with aircraft ground. - Spend at least an hour looking for lost tools due to bad workshop rutines (not putting things back after use). - added heat shrink to al exposed connectors with positive current - got wet feet dragging the Rans around to register new values for the whiskey compass deviation table - drove odd hundred kilometers to pick up welding equipment, certified scales, loctite from the car supply store etc. - spend many hours online reading about installation processes and searching for bolts, o-rings, hose nipples etc. - plus all the other minor tasks and nags, happily forgotten now that the work is all done and the Rans sits with a brand new 80HP engine, and the
Took the propeller to the comunity's "Grand ol' man" of propellers, Finn Snitter, for checking the propellers balance and pitch. Finn rounded the tips to reduce noise and vibrations caused by tip vortices.
Finally! Flew the Rans to its new home at EKRN Roenne, Bornholm. The trip includes a 22 NM water crossing with height restrictions, so wore a Survival suit as a safety measure. The engine ran smoothly all the way though, and what a great trip it was. The first part was a formation flight with Olav in a Fly Synthesis Storch and Ole in the Rans S6.
Takeoff in light wind with one person on board and full fuel tanks.
This video shows the typical cruise speed at 4600 RPM of about 95 MPH. At 4800 RPM the cruise speed is appx. 100 MPH indicated.