Rotax Install

Rotax 912 series discussion.

Rotax Install

Postby pauldblackmore » Fri Jan 06, 2017 12:04 am

Hi All,

I would like to share a few photos of my current project to replace the aerovee with a Rotax 912 ULS on my Sonex Tri Gear. Please see the link below.

https://postimg.org/gallery/vgl6zjqi/

Please let me know if you have any questions or comments.

Cheers

Paul
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Re: Rotax Install

Postby ihab » Fri Jan 06, 2017 1:38 am

Awesome! Are you aware of garyb's work?

http://www.sonexbuilders.net/viewtopic. ... tax#p25706

Ihab
Ihab Awad, San Jose, CA
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Re: Rotax Install

Postby Concorde » Fri Jan 06, 2017 9:01 am

Looks great . Is the motor mount your design ? Also that doesn't look like Sonex nose gear ,did you have to change it because of the new motor mount ?
I was planning on 3300 , but with everything going on......who knows.
I will follow your build with great interest.
Thanks
Ben
Ben
Sonex # 1684
Tri-Gear, Dual Control
Rotax 912uls
N379BS reserved.
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Re: Rotax Install

Postby pauldblackmore » Fri Jan 06, 2017 9:08 pm

Thanks for the reference to Garyb Ihab. Yes I do know Gary, he lives about 30 mins drive from me and we have shared our ideas on the Rotax install. I'm grateful for Gary's advice - its a race to the finish now :)

Ben, the motor mount is designed by my brother in law - a professional mech eng. Its all been modeled in Solidworks and stress analysed so we are pretty confident with it. The great thing about modeling the FWF install in 3D Cad is that we have been able to mess around with positioning all of the ancillary items to get a good tidy install before cutting metal.

With regards to the nose gear, It is necessary to do something to provide more ground clearance as the Rotax needs a larger prop. I'll be running a 62" 3 blade ground adjustable (Bolly). Apart from more clearance I also wanted to increase the size of the nose wheel to 5" as I will operate mostly from grass fields. I also (personal opinion) don't like the appearance of the standard fork. The nose fork is from a PA38 Tomahawk, I just cut off the old fork and the new fork and strut slides over the existing fork strut. This approach is adding weight, but with the 912 some extra weight up front is a good thing for W&B. I have some residual concern over how it will perform in flight - will the additional frag forward of the CoG affect longitudinal stability? - We will see....

I too looked at Jab 3300 or Camit for the upgrade, It would have been much easier, but my objective is to obtain the most reliable 100hp+ FWF package I can engineer. The 912 Sonex should perform quite well.

Paul
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Re: Rotax Install

Postby bishoff7 » Wed Feb 01, 2017 9:33 pm

Hi Paul
You are going to love the performance you are going to get out of the rotax in the sonex it really is impressive .
Have you got around to the cowling as yet ,I ask because even using acad I found it a bit of a challenge.
I really think where you have mounted your radiator is a good choice as it does not restrict your exhaust placement.
Congrats to you and Gary I think both of you are doing a spot on job
Regards Bish.
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Re: Rotax Install

Postby pschwenn » Sun Jul 02, 2017 1:31 pm

Dear Paul Blackmore (& Garyb),

I'm looking for best way forward for Rotax mount for series A Xenos (tailwheel of course). Could another like yours be built? What about Garyb's? Do you have any information on the Series-B SonexAircraft Rotax mount (I realize it might need adapting, but depending on how much adapting, it could be a valid way to proceed)?

Thanks, Peter Schwenn

[/quote="pauldblackmore"]Thanks for the reference to Garyb Ihab. Yes I do know Gary, he lives about 30 mins drive from me and we have shared our ideas on the Rotax install. I'm grateful for Gary's advice - its a race to the finish now :)

Ben, the motor mount is designed by my brother in law - a professional mech eng. Its all been modeled in Solidworks and stress analysed so we are pretty confident with it. The great thing about modeling the FWF install in 3D Cad is that we have been able to mess around with positioning all of the ancillary items to get a good tidy install before cutting metal.
...
I too looked at Jab 3300 or Camit for the upgrade, It would have been much easier, but my objective is to obtain the most reliable 100hp+ FWF package I can engineer. The 912 Sonex should perform quite well.

Paul[/quote]
6514 41st Ave
University Park MD 20782

240-602-6931

N16XN under construction
N32SX @ KCGS (912iS being installed)
http://www.schwenn.com
Eaa4 - KCGS College Park MD
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Re: Rotax Install

Postby pschwenn » Sun May 06, 2018 10:47 pm

Rotaxers to be,

Installation:

I'm just starting installation of an 912iS Sport on my Xenos. I've been studying the 912 and the 915 for a couple of years, reading the installation manuals and hoping for an fwf kit for Sonex (less prop and mount). Though I'm just starting, I thought others might appreciate a list of components and procedures.

The attractions for me of the 912iS Sport are reliability and time saved from engine fiddling, low operation cost (very low gph, mogas, even ethanol ok), big boost in range, power, ubiquity, and wide high torque curve. It is also light (about 160lbs all told) and of modern design throughout.
Since there are several 912 variants, be aware that most of what's here is for the fuel injected 912iS Sport with dual ECUs and an improved airbox giving reduced fuel consumption. I'll try as I proceed to edit this to take account of carburated versions. The basic difference for components is that High Pressure versions of various components are required for the fuel system of the fuel injected version, and that two fuel filters (and two fuel pumps [supplied]) are required.) However using hose appropriate to a hp system will not degrade an installation in which that is not needed. This procedure is not for a 915iS Turbo: that engine is considerably more complex, likely unnecessarily powerful for Sonex (140hp) and costs $38K+ . As you work keep in mind that the Weight and Balance of your modified airplane must be redone and especially fore'n'aft weight distribution and overall weight, possibly corrected.
Keep in mind while the Sonexes are acrobatic, the Rotax is not except (5 secs at -.5g). Since it is dry sump and fuel injection it has the potential but it would require significant modifications/additions to oil cooler and tank (and internal oil pickup(s)), gearbox lubrication, radiator/expansion tank/overflow, fuel tanks, breathers,...

Make plans for proper inspection of your installation in advance. My plane is Experimental. Yours may require inspection and certification (ASTM for LSA) of individual components at a higher level than mine, but nothing I will list is of low quality to get a low cost. Prices listed are likely the worst you could do.

I will incorporate suggestions you all make as appropriate - make your contributions!

Photographically document your existing installation. Label all wires, hoses, & cables. Verify the good functioning of your current electrics, engine controls, and avionics.

Setup a reasonable place to work.

Remove peripheral gear of your existing installation (exhaust, ...) that you will not reuse or will move. If you have an existing engine, remove the propeller. Remove the engine. Remove the engine mount. Pickle your old engine (see installation manual re: engine storage), label anything you couldn't get at before.

Assuming for the moment you already have fuel tank, electrical power infrastructure, battery, starter solenoid, engine mount for Rotax, propeller (see other discussions), cowl, throttle control & cable, mixture ditto, and air/oil separator breather. Voltage regulators for Rotax are built in. A possible propeller (for Sonex and Waiex) is an "Helice E-Prop Durandal (about $1600+spinner, extension free) 100 (80 for 80hp) S 160cm [M 165cm" , for slower Xenos for which you'll need greater ground clearance - say by bigger/taller tires] (these props are ground adjustable 3-blade). Or you may prefer the Sonex suggested Sensenich. Part of the enjoyment is researching possible propellers.

You'll likely find in the delivered engine box: engine, oil, radiator expansion canister, oil supply canister, fuse boxes, electronic control units, fuel pump(s) assembly. Keep the shipping container, palette and shipping connectors in good shape and set it aside indoors.

Look through the Rotax Installation Manual for your engine, and mark the points specific to your engine. Browse the Pipistrel installation pdf: "Rotax-912iS-Mounting-the-Engine-on-the-Airframe.pdf". Watch the Rotax Install Tips and Techniques video on DVD ($35 or likely free in your engine's manual packet). If you have an appetite for repetition watch the CH750 912 installation video - tho the Header Tank/Fuel System content is largely irrelevant.

Do not use force on hose or wire or connectors to complete a connection. All connections except control cables must have slack mid-run.

Because of the position of your fuel tank there is no need for metallic tube fluid connections (no long runs). As a first approximation Teflon hose can be used for everything. (But you will save big by using oil cooler and radiator specific hose for those cooling systems.) For airplanes TEFLON (PTFE) will have a wound steel wire covering. Where possibility of fire is real near a hose, use a hose with a fire shield covering. Avoid this as much as possible by not routing any hose or wire by fire hazards. Make sure to use hose of adequate internal dimensions - see Installation Manual. Use angled hose connectors where necessary to avoid sharp bends in hoses. Gentle bends are a good thing.

For inveterate savers. If you follow the requirements for flow & cooling capacity, back pressure etc (see Installation Manual) you would be well to start with the exhaust (but get the top-most flange pipes unless you are a machinist), the radiator, the oil cooler (for example a thin experimental mounted for surface effect), & overflow bottle. Make or adapt your own mounting brackets. For carburated engine no need for High Pressure: filters, Gascolator, Complex breather, and (if any) check-valve. Battery (Rotax voltage regulator will only give you 14.2V anyway which will not fully or quickly charge a Lithium-IRON battery (Do not use a Lithium-Ion battery). I use Shorai Lithium-Iron. If you do find a way to use Lithium-Iron you'll likely save money by using the more expensive Earth-X batteries which have built-in protective controllers.. You can avoid expensive sensor kits, and EGT. Don't get sensors before checking which if any are already built-in Don't skrimp on hose or hose diameter, but you might save by using simpler connectors. The fuel consumption for the 912iS Sport is so low you might be able to save the extra cost (of the iS Sport) (comparing 3gph at $2.50/gal = $7.50/hr with Aerovee with 5gph [yes, both engines can do a little better occasionally] at $5.50/gal = $27.50/hr, this savings could be relatively quick.

You'll have to acquire separately what you might have thought would have been in the box:
    Oil cooler (if required), e.g. stock Rotax for your engine $265
    Header pipes, muffler & (exhaust pipe(s) if not integral to muffler), e.g. stock Rotax for your engine $1450
    Radiator e.g. stock Rotax for your engine $483
    Overflow bottle e.g. Rotax stock $53
    Gascolator (high pressure (hp), if fuel injection(fi)), e.g. ACS HP Gascolator, $118
    Gascolator firewall mounting flange, $22
    Fuel filter(s) (hp if fi; one fine, one coarse if fi), e.g. AN6 HP Micron 10 $88, bracket $12; Phoenix Select-Flo 100 micon $75 (but get and use the 67 micron screen accessory)
    One way hp check valve depending on engine (hp if fi), e.g.ACS Free-Flo One-Way check valve $35
    Air/Oil breather e.g. ASI $170, install kit $52
Relative Poistioning:
    ECU mounts in the Cockpit!
    Engine fuse boxes mount with engine in cowl but at a good distance from high heat. Pay attention to the separation of hoses, wires and "sensitive" components from high heat, vibration, and sharp edges.
    Radiator best mounts BELOW the engine, never attached to the engine. If mounted above engine substitute an Accumulaor for the Expansion which now mount remotely above all, with overflow bottle below.
    Expansion Tank mounts ABOVE the engine.

    Oil SupplyTank mounts above the Oil Cooler- the ideal position is with the oil level in the tank at the same level as the oil pump - which is 14.17 inches below the propellor shaft, within 10 degrees of engine vertical axis; never attached to the engine.
    Oil cooler mounts below the oil pump, its caps pointing up, never attached to the engine. Flexible but not loose mount, nor subject to cracking.
    The oil cooler can mount above the engine - but as with radiator, caps always highest. And high mount must still test with flow and cooling within specs.
Once you have all these pieces in position or before depending on how you plan, you'll need:

    Firewall passage sealing compound, e.g. Permatex Ultra Black $10 (tho you might be required to use an aircraft product)
    Loctite medium strength, high strength and "reqires serious tools" strength. About $20 total.
    Hoses and hose connectors (see later on) e.g. Teflon with steel wire wrap covering, e.g. Aeroquip 666 or Stratoflex for fuel, specialized oil cooler and radiator hose (much much cheaper).
    If desired for Fuel hose Aeroquip AE466 has Silicone firesleeve, or firesleeve can be incorporated separately. Use radiator hose where needed to protect any hose from edge, heat or bend.
    Use specialized hose and connectors where specified by Installation manual - these can often be simpler and cheaper than standardized connectors for AE666 or other.
    Sensor set appropriate to both your EMS and the Rotax (check first which have already been supplied and incorporated) e.g. 2 x CHT, Oil T&P, Water T, Fuel Pressure (2 x EGT - if desired; Rotax doesn't seem to think this useful/important); very roughly $400 (you can do much worse.)
    Air filter: e.g. K&N cleanable/reuseable, medium sized can shape with proper throat diam. and screw clamp. Clean and re-oil per K&N's instructions. About $20 dollars.
    For true ram air intake, you're on your own - and you might well reduce power compared to well conceived Rotax airbox. Ditto exhaust. But drawing cool air from special cowl input rather than hot engine compartment is a no-brainer.
    The hardest part of the installation might well be the following three innocuous looking items:
    Mounting brackets,
    Wires and connectors as needed. If you use crimped electrical connectors, use a crimper which does proper folding not just crushing, and use aerospace or industrial quality connectors (not such as: 480 connectors from unknown source for $25). Use heat shrink crimp connectors or do your own heat shrinking or liquid electrical tape. For hose connections, keep in mind that few of the connections will be made by pushing the tubing onto a barbed or beaded spigot already present on the component - look carefully at the example photographs and the parts lists. But you will seldom if ever have to use $100 stainless steel certified hose connectors.
    Screws, bolts, washers, grommets, as needed


Make initial cowl modifications to accommodate oil cooler, radiator, exhaust system. Plan cooling baffles for cowl - the heads are water and oil-cooled, the cylinders are airflow cooled, as are the oil cooler and the radiator.

Start taking photographs now at each significant step.

Free up access to your avionics and firewall. A likely consequence of integrating your electric/avionics with the Rotax is inadvertent damage to your panel wiring, from inconvenient access.

Mount peripheral gear, especially on the firewall that may be difficult after the engine mount is in place, such as the gascolator, battery, engine fuse box, coolant overflow bottle, oil tank (see note below on vertical height), the air/oil separator breather (if needed); starter solenoid, voltage regulator (if not integral to alternator) and any coils that are not integral to with engine, firewall penetrating gizmos, and other items applicable in the case of your particular engine variant. Mount major components: engine mount, engine, throttle and mixture (or choke) controls, propellor, expansion canister. Check propeller ground clearance. If you have less then 9 inches with the plane level regardless of type, do something about it, especially if your tie down or route to runway is not smooth pavement without gravel.

Mount air/oil separator breather return if engine requires, and when applicable, fuel filters, fuel pumps, ECU (in the cabin), and engine fuse boxes if not already on the firewall. Make sure your filters are in a progression of coarseness, e.g. for fuel injection: gascolator 100, coarse 67, (pumps) fine 10, (injectors) or or coarse, gasgolator, fine., or no gascolator.
Make hose & electrical connections between them, and create bypass circuit if required. For fuel injected return line, consider using a larger diameter tube than the feed because otherwise any added bubbles or vapor, in increasing the return volume, can act as a brake on the feed flow.

Mount minor components and connect. Make final cowl changes: shape, inlets, outlets; leave space and structure for later modifications. Complete your baffling. Rotax cylinders, (not heads) require ram air cooling, but they are not sitting out in plain reach of that air, so you need to explicitly route air to them thru the other neighboring components, or $$$ for Rotax standard cyclinder cooling baffle/hood/intake. For.

Finish connections thru firewall: Sensors, engine controls, ECU, fuel.

Look through Installation Manual again. Watch the tips and techniques video again: those sections devoted to finishing up. Don't forget to add oil as indicated there (learn the Rotax oil "burp"), and coolant - use conventional coolant, with 50% water, do not use undiluted or unconventional coolant. Oil should be high-perfomance 4-cycle motorcycle oil (i.e. for integrated transmissions), likely 10-40W or 15-50W synthetic or semi-synthetic.

Redo your weight and balance calculations. Correct esp. the fore'n'aft weight distribution if necessary, and overall weight if over.

Verify all assemblies, connections & fluids. Recheck torque on fundamental mounting bolts. Shake things, tap things, wiggle things. Heat wrap all of the exhaust system inside the cowl - otherwise your efforts to cool the engine are competing with very hot radiating bits.

Perform all tests in Installation Manual. Including pressure tests.

Test electric subsystems in isolation. Put your panel back in position.

Save your photographic record.

Do not start the engine without propeller properly mounted.

Look through the Rotax Operations Manual for your engine.

Set up the adjustable propeller if you have one.

Follow installation manual for first running tests. Measure for heat concentrations within cowl as soon as possible after first runs. Revise cowl and baffling to deal with any obvious uneven or excessive heating. Follow any Troubleshooting if required.

Dynamic propeller balance if required.

After initial use, recheck all connections, especially hoses and structural bolts. Look for leaks and loose wires, interference between components,

Readjust adjustable propeller if you have one.

Follow break-in procedures.

---------------------------------------------------------------------------- fin -------------------------------------------------------
6514 41st Ave
University Park MD 20782

240-602-6931

N16XN under construction
N32SX @ KCGS (912iS being installed)
http://www.schwenn.com
Eaa4 - KCGS College Park MD
pschwenn
 
Posts: 25
Joined: Fri Jul 03, 2015 8:22 pm
Location: 6514 41st Avenue, University Park, MD 20782

Re: Rotax Install

Postby killerfish72 » Sat Sep 08, 2018 9:08 am

Outstanding post! Any update/pics of your install? Im considering (still!) building a Sonex B with a Rotax 912iS.

pschwenn wrote:Rotaxers to be,

Installation:

I'm just starting installation of an 912iS Sport on my Xenos. I've been studying the 912 and the 915 for a couple of years, reading the installation manuals and hoping for an fwf kit for Sonex (less prop and mount). Though I'm just starting, I thought others might appreciate a list of components and procedures.

The attractions for me of the 912iS Sport are reliability and time saved from engine fiddling, low operation cost (very low gph, mogas, even ethanol ok), big boost in range, power, ubiquity, and wide high torque curve. It is also light (about 160lbs all told) and of modern design throughout.
Since there are several 912 variants, be aware that most of what's here is for the fuel injected 912iS Sport with dual ECUs and an improved airbox giving reduced fuel consumption. I'll try as I proceed to edit this to take account of carburated versions. The basic difference for components is that High Pressure versions of various components are required for the fuel system of the fuel injected version, and that two fuel filters (and two fuel pumps [supplied]) are required.) However using hose appropriate to a hp system will not degrade an installation in which that is not needed. This procedure is not for a 915iS Turbo: that engine is considerably more complex, likely unnecessarily powerful for Sonex (140hp) and costs $38K+ . As you work keep in mind that the Weight and Balance of your modified airplane must be redone and especially fore'n'aft weight distribution and overall weight, possibly corrected.
Keep in mind while the Sonexes are acrobatic, the Rotax is not except (5 secs at -.5g). Since it is dry sump and fuel injection it has the potential but it would require significant modifications/additions to oil cooler and tank (and internal oil pickup(s)), gearbox lubrication, radiator/expansion tank/overflow, fuel tanks, breathers,...

Make plans for proper inspection of your installation in advance. My plane is Experimental. Yours may require inspection and certification (ASTM for LSA) of individual components at a higher level than mine, but nothing I will list is of low quality to get a low cost. Prices listed are likely the worst you could do.

I will incorporate suggestions you all make as appropriate - make your contributions!

Photographically document your existing installation. Label all wires, hoses, & cables. Verify the good functioning of your current electrics, engine controls, and avionics.

Setup a reasonable place to work.

Remove peripheral gear of your existing installation (exhaust, ...) that you will not reuse or will move. If you have an existing engine, remove the propeller. Remove the engine. Remove the engine mount. Pickle your old engine (see installation manual re: engine storage), label anything you couldn't get at before.

Assuming for the moment you already have fuel tank, electrical power infrastructure, battery, starter solenoid, engine mount for Rotax, propeller (see other discussions), cowl, throttle control & cable, mixture ditto, and air/oil separator breather. Voltage regulators for Rotax are built in. A possible propeller (for Sonex and Waiex) is an "Helice E-Prop Durandal (about $1600+spinner, extension free) 100 (80 for 80hp) S 160cm [M 165cm" , for slower Xenos for which you'll need greater ground clearance - say by bigger/taller tires] (these props are ground adjustable 3-blade). Or you may prefer the Sonex suggested Sensenich. Part of the enjoyment is researching possible propellers.

You'll likely find in the delivered engine box: engine, oil, radiator expansion canister, oil supply canister, fuse boxes, electronic control units, fuel pump(s) assembly. Keep the shipping container, palette and shipping connectors in good shape and set it aside indoors.

Look through the Rotax Installation Manual for your engine, and mark the points specific to your engine. Browse the Pipistrel installation pdf: "Rotax-912iS-Mounting-the-Engine-on-the-Airframe.pdf". Watch the Rotax Install Tips and Techniques video on DVD ($35 or likely free in your engine's manual packet). If you have an appetite for repetition watch the CH750 912 installation video - tho the Header Tank/Fuel System content is largely irrelevant.

Do not use force on hose or wire or connectors to complete a connection. All connections except control cables must have slack mid-run.

Because of the position of your fuel tank there is no need for metallic tube fluid connections (no long runs). As a first approximation Teflon hose can be used for everything. (But you will save big by using oil cooler and radiator specific hose for those cooling systems.) For airplanes TEFLON (PTFE) will have a wound steel wire covering. Where possibility of fire is real near a hose, use a hose with a fire shield covering. Avoid this as much as possible by not routing any hose or wire by fire hazards. Make sure to use hose of adequate internal dimensions - see Installation Manual. Use angled hose connectors where necessary to avoid sharp bends in hoses. Gentle bends are a good thing.

For inveterate savers. If you follow the requirements for flow & cooling capacity, back pressure etc (see Installation Manual) you would be well to start with the exhaust (but get the top-most flange pipes unless you are a machinist), the radiator, the oil cooler (for example a thin experimental mounted for surface effect), & overflow bottle. Make or adapt your own mounting brackets. For carburated engine no need for High Pressure: filters, Gascolator, Complex breather, and (if any) check-valve. Battery (Rotax voltage regulator will only give you 14.2V anyway which will not fully or quickly charge a Lithium-IRON battery (Do not use a Lithium-Ion battery). I use Shorai Lithium-Iron. If you do find a way to use Lithium-Iron you'll likely save money by using the more expensive Earth-X batteries which have built-in protective controllers.. You can avoid expensive sensor kits, and EGT. Don't get sensors before checking which if any are already built-in Don't skrimp on hose or hose diameter, but you might save by using simpler connectors. The fuel consumption for the 912iS Sport is so low you might be able to save the extra cost (of the iS Sport) (comparing 3gph at $2.50/gal = $7.50/hr with Aerovee with 5gph [yes, both engines can do a little better occasionally] at $5.50/gal = $27.50/hr, this savings could be relatively quick.

You'll have to acquire separately what you might have thought would have been in the box:
    Oil cooler (if required), e.g. stock Rotax for your engine $265
    Header pipes, muffler & (exhaust pipe(s) if not integral to muffler), e.g. stock Rotax for your engine $1450
    Radiator e.g. stock Rotax for your engine $483
    Overflow bottle e.g. Rotax stock $53
    Gascolator (high pressure (hp), if fuel injection(fi)), e.g. ACS HP Gascolator, $118
    Gascolator firewall mounting flange, $22
    Fuel filter(s) (hp if fi; one fine, one coarse if fi), e.g. AN6 HP Micron 10 $88, bracket $12; Phoenix Select-Flo 100 micon $75 (but get and use the 67 micron screen accessory)
    One way hp check valve depending on engine (hp if fi), e.g.ACS Free-Flo One-Way check valve $35
    Air/Oil breather e.g. ASI $170, install kit $52
Relative Poistioning:
    ECU mounts in the Cockpit!
    Engine fuse boxes mount with engine in cowl but at a good distance from high heat. Pay attention to the separation of hoses, wires and "sensitive" components from high heat, vibration, and sharp edges.
    Radiator best mounts BELOW the engine, never attached to the engine. If mounted above engine substitute an Accumulaor for the Expansion which now mount remotely above all, with overflow bottle below.
    Expansion Tank mounts ABOVE the engine.

    Oil SupplyTank mounts above the Oil Cooler- the ideal position is with the oil level in the tank at the same level as the oil pump - which is 14.17 inches below the propellor shaft, within 10 degrees of engine vertical axis; never attached to the engine.
    Oil cooler mounts below the oil pump, its caps pointing up, never attached to the engine. Flexible but not loose mount, nor subject to cracking.
    The oil cooler can mount above the engine - but as with radiator, caps always highest. And high mount must still test with flow and cooling within specs.
Once you have all these pieces in position or before depending on how you plan, you'll need:

    Firewall passage sealing compound, e.g. Permatex Ultra Black $10 (tho you might be required to use an aircraft product)
    Loctite medium strength, high strength and "reqires serious tools" strength. About $20 total.
    Hoses and hose connectors (see later on) e.g. Teflon with steel wire wrap covering, e.g. Aeroquip 666 or Stratoflex for fuel, specialized oil cooler and radiator hose (much much cheaper).
    If desired for Fuel hose Aeroquip AE466 has Silicone firesleeve, or firesleeve can be incorporated separately. Use radiator hose where needed to protect any hose from edge, heat or bend.
    Use specialized hose and connectors where specified by Installation manual - these can often be simpler and cheaper than standardized connectors for AE666 or other.
    Sensor set appropriate to both your EMS and the Rotax (check first which have already been supplied and incorporated) e.g. 2 x CHT, Oil T&P, Water T, Fuel Pressure (2 x EGT - if desired; Rotax doesn't seem to think this useful/important); very roughly $400 (you can do much worse.)
    Air filter: e.g. K&N cleanable/reuseable, medium sized can shape with proper throat diam. and screw clamp. Clean and re-oil per K&N's instructions. About $20 dollars.
    For true ram air intake, you're on your own - and you might well reduce power compared to well conceived Rotax airbox. Ditto exhaust. But drawing cool air from special cowl input rather than hot engine compartment is a no-brainer.
    The hardest part of the installation might well be the following three innocuous looking items:
    Mounting brackets,
    Wires and connectors as needed. If you use crimped electrical connectors, use a crimper which does proper folding not just crushing, and use aerospace or industrial quality connectors (not such as: 480 connectors from unknown source for $25). Use heat shrink crimp connectors or do your own heat shrinking or liquid electrical tape. For hose connections, keep in mind that few of the connections will be made by pushing the tubing onto a barbed or beaded spigot already present on the component - look carefully at the example photographs and the parts lists. But you will seldom if ever have to use $100 stainless steel certified hose connectors.
    Screws, bolts, washers, grommets, as needed


Make initial cowl modifications to accommodate oil cooler, radiator, exhaust system. Plan cooling baffles for cowl - the heads are water and oil-cooled, the cylinders are airflow cooled, as are the oil cooler and the radiator.

Start taking photographs now at each significant step.

Free up access to your avionics and firewall. A likely consequence of integrating your electric/avionics with the Rotax is inadvertent damage to your panel wiring, from inconvenient access.

Mount peripheral gear, especially on the firewall that may be difficult after the engine mount is in place, such as the gascolator, battery, engine fuse box, coolant overflow bottle, oil tank (see note below on vertical height), the air/oil separator breather (if needed); starter solenoid, voltage regulator (if not integral to alternator) and any coils that are not integral to with engine, firewall penetrating gizmos, and other items applicable in the case of your particular engine variant. Mount major components: engine mount, engine, throttle and mixture (or choke) controls, propellor, expansion canister. Check propeller ground clearance. If you have less then 9 inches with the plane level regardless of type, do something about it, especially if your tie down or route to runway is not smooth pavement without gravel.

Mount air/oil separator breather return if engine requires, and when applicable, fuel filters, fuel pumps, ECU (in the cabin), and engine fuse boxes if not already on the firewall. Make sure your filters are in a progression of coarseness, e.g. for fuel injection: gascolator 100, coarse 67, (pumps) fine 10, (injectors) or or coarse, gasgolator, fine., or no gascolator.
Make hose & electrical connections between them, and create bypass circuit if required. For fuel injected return line, consider using a larger diameter tube than the feed because otherwise any added bubbles or vapor, in increasing the return volume, can act as a brake on the feed flow.

Mount minor components and connect. Make final cowl changes: shape, inlets, outlets; leave space and structure for later modifications. Complete your baffling. Rotax cylinders, (not heads) require ram air cooling, but they are not sitting out in plain reach of that air, so you need to explicitly route air to them thru the other neighboring components, or $$$ for Rotax standard cyclinder cooling baffle/hood/intake. For.

Finish connections thru firewall: Sensors, engine controls, ECU, fuel.

Look through Installation Manual again. Watch the tips and techniques video again: those sections devoted to finishing up. Don't forget to add oil as indicated there (learn the Rotax oil "burp"), and coolant - use conventional coolant, with 50% water, do not use undiluted or unconventional coolant. Oil should be high-perfomance 4-cycle motorcycle oil (i.e. for integrated transmissions), likely 10-40W or 15-50W synthetic or semi-synthetic.

Redo your weight and balance calculations. Correct esp. the fore'n'aft weight distribution if necessary, and overall weight if over.

Verify all assemblies, connections & fluids. Recheck torque on fundamental mounting bolts. Shake things, tap things, wiggle things. Heat wrap all of the exhaust system inside the cowl - otherwise your efforts to cool the engine are competing with very hot radiating bits.

Perform all tests in Installation Manual. Including pressure tests.

Test electric subsystems in isolation. Put your panel back in position.

Save your photographic record.

Do not start the engine without propeller properly mounted.

Look through the Rotax Operations Manual for your engine.

Set up the adjustable propeller if you have one.

Follow installation manual for first running tests. Measure for heat concentrations within cowl as soon as possible after first runs. Revise cowl and baffling to deal with any obvious uneven or excessive heating. Follow any Troubleshooting if required.

Dynamic propeller balance if required.

After initial use, recheck all connections, especially hoses and structural bolts. Look for leaks and loose wires, interference between components,

Readjust adjustable propeller if you have one.

Follow break-in procedures.

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Re: Rotax Install

Postby garyb » Sun Sep 09, 2018 1:58 am

Sonex #1531 Rotax 912ULS. 250 hours and counting.
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Location: Auckland New Zealand

Re: Rotax Install

Postby killerfish72 » Sun Sep 09, 2018 4:55 pm

Thanks Gary, very impressive! I am most interested in a 912is install. Curious how that has gone
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