Rans S-21 OUTBOUND User manual

09/11/2018
S-21 OUTBOUND
ROTAX 915iS INSTALLATION
TEXT MANUAL
Serial Number:
Registration Number:
COPYRIGHT ©
RANS DESIGNS
4600 HWY 183 Alt
HAYS, KANSAS, USA 67601
785-625-6346
www.rans.com

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RANS S-21 OUTBOUND TEXT MANUAL 14-1
BEFORE BEGINNING ASSEMBLY
TAKE INVENTORY:
You must complete an inventory within 60 days
of receiving your kit.
We check and re-check and are 99.9% certain that if we say we shipped it, we did. The
first task in building your kit is to inventory the parts using the packing list provided. It is
your job to keep all parts organized and accounted for. We cannot provide missing parts
cost free after 60 days. Use the supplied pack list to verify that everything that we
packed is in the box. The fast way to inventory is to use the Priority Number that
appears on the Part Number labels, these will match the pack list in numeric order. Go
through the list item by item. If anything is not there that should be, please contact our
parts department immediately.

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RANS S-21 OUTBOUND TEXT MANUAL 14-2
ROTAX 915iS - ENGINE MOUNT INSTALLATION
(AFTER FIT-UP OF FIREWALL & BOOT COWL)
ASSEMBLY
1. Become familiar with the ROTAX 915iS PARTS MANUAL DRAWINGs and
collect the parts shown in the drawing.
2. Modify the firewall in accordance with FIGURES 11-01/915iS through FIGURES
11-01L/915iS
ROTAX 915iS – FIREWALL ITEMS INSTALLATION
1. Gather the applicable parts shown in the parts manual.
2. Modify the firewall to match FIGURES 11-01/915iS – 11-01L/915iS. Fit the firewall
to the fuselage before, and double check that the placement of the items will not
interfere with the welded cage structure.
3. Cut the spacer bushings from raw stock and attach the oil bottle mount to the
firewall. Then secure the oil bottle to the oil bottle mount using hose clamps.
NOTE: The orientation of the top of the oil bottle does matter, but can be
repositioned when installing the oil lines, adjust the clamp that holds the oil bottle
cap to the oil bottle, so it is easier to service at time intervals and condition
inspections.
4. Rivet the mount bracket for the coolant recovery bottle to the firewall and secure the
coolant recovery bottle to the bracket via hose clamp.
5. The firewall pass through holes can be made from the raw stock provided or
sourced through vendors such as aircraft spruce.
(AFTER INSTALLING ALL ACCESSORIES ON FIREWALL)
ENGINE MOUNT INSTALLATION
1. Become familiar with the ROTAX 915iS PARTS MANUAL DRAWINGS and collect
the parts shown in the drawing.
2. Install Engine Mount after making sure all accessories are located on firewall.
3. Ream the engine mount bushings of the engine mount and the bushings in the
cage on the firewall using a 5/16” ream.

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RANS S-21 OUTBOUND TEXT MANUAL 14-3
4. Bolt the engine mount to the firewall. Note the hardware orientation. NOTE: Before
torquing hardware, look ahead at the electrical parts page, some of the 4 AWG
ground wires attach to the upper right-hand bolt of the engine mount. NOTE: If
building a trike, place the trike nose gear mount behind the engine mount and leave
the two spacer washers out.
5. Torque the hardware to AN Standards.
6. Bolt the ROTAX Suspension Mount (supplied on your 915iS) to the RANS AFT
mount using the hardware, spacers and rubber isolators called out in the parts
manual. NOTE: The ROTAX Suspension Mount holes are 10.5mm, while the
hardware called out is 3/8”. This is as intended by ROTAX. Also note that they
have a supplied welded on nut down by the Turbo that will be used during the
installation.
7. Once the ROTAX Suspension Mount is properly torqued to the AFT Mount, safety
wire the lower right hand bolt head to the engine mount frame. This is the nut that
is welded to the turbo bracket, and the only nut that is not a self-locking nut.
ROTAX 915iS - ENGINE ELECTRICAL
(FINAL INSTALL OF ENGINE)
Due to the wide selection of switches, circuit breakers, connectors, gauges,
flight systems, etc., which may be used RANS builders, RANS does not
supply these items with the kit.
Electrical wiring can be aided with the use of Buss Bars for Master, Ground and Avionic
power.
(ECU INSTALLATION)
1. Refer to the parts catalog and select the required components for assembly.
2. Drill four holes in the firewall at the locations depicted on FIGURE 11-01/915iS &
11-01A/915iS.
3. Cut the four spacer bushings from raw stock.
4. Attach the Engine Control Unit to the firewall as shown in the parts diagram.
(SOLENOIDS INSTALLATION)
5. Refer to the parts catalog and select the required components for assembly.
6. Drill two holes in the firewall at the locations depicted on FIGURES 11-01/915iS
& 11-01B/915iS for the start solenoid. These holes will be upsized large enough
for the grommet to be inserted.

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RANS S-21 OUTBOUND TEXT MANUAL 14-4
7. Insert the grommet into the firewall. The isolator plate will go around the
grommets and isolate the starter solenoid from the firewall. Pin the Starter
solenoid to the firewall through the grommets.
8. Tighten the hardware to a snug fit, but do not overtighten. There should be very
little movement in the solenoid.
9. Drill two holes in the firewall at the locations depicted on FIGURES 11-01/915iS
& 11-01B/915iS for the master solenoid. Bolt the master solenoid to the firewall
and tighten the hardware.
(FUSEBOX INSTALLTION)
1. Refer to the parts catalog and select the required components for assembly.
2. Fabricate two pieces from baggage compartment angles to make two fuse box
mounting angles. Refer to FIGURE 11-02/915iS.
NOTE: These measurements are for reference only, please double
check them to your fuse box and engine mount.
3. Assemble the fuse box to the two mounting angles. Tighten all hardware.
4. Using the #30 hole called out in FIGURE 11-02/915iS, cleco the PCV Mount to
the angle, align the mount perpendicular to the fuse box mount angles. Transfer
drill the rest of the #30 holes. Debur the holes and cleco back in place.
5. Attach the mounting angles to the engine mount in the location provided in
FIGURE 11-02A/915iS. Tighten all hardware.
6. Position the PCV mount plate on the backside of the fuse box mount angles.
NOTE: Position in a way that avoids kinks in the tubing coming off the pressure
control valve. Install the PCV to the PCV mount. Rivet the mount plate to the
angles.
7. Install all supplied battery cables in accordance with the parts manual.
NOTES: Where the battery cables attach to the engine mount, it is
best practice to sand the powder coat down to bare metal for a
good ground. There should be no continuity between the
“AIRFRAME” ground and the “EMS” ground of the fuse box. Refer
to your ROTAX 915iS Installation manual for further details.
ROTAX 915iS – OPTIONAL BATTERY BOX ASSEMBLY &
INSTALLATION
(FINAL INSTALL OF ENGINE)
ASSEMBLY
1. Refer to the parts catalog and select the required components for assembly.
2. Firewall should have been drilled to match FIGURE 11-01C/915iS or 11-
01E/915iS, depending on which battery you have chosen.

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RANS S-21 OUTBOUND TEXT MANUAL 14-5
NOTE: Depending on the battery option used, these four holes through
the firewall will be different.
Power Sonic Battery Box
3. Cleco Support Angles to inside of Front Plate. Refer to the PARTS MANUAL
DRAWING. Transfer drill #30 and rivet. Base of Battery will set on Support
Angles.
4. Align one edge of Battery Box Front Plate with edge of Battery Box Mount Plate.
Clamp together and transfer drill #11 though upper and lower mount holes in
Mount Plate and cleco.
5. Slip Battery into assembly. Align free edge of Plates; pull Front Plate against
battery. Check to see if Battery can be slid in and out. If battery cannot be slid in
and out, then loosen fit slightly to allow easier removal. Clamp and transfer drill
#11 through upper and lower mount holes and cleco.
6. Transfer drill #30 the center holes in Mount Plate, and rivet from the AFT side.
7. Slide the Battery Bar through the holes in the Battery Box assembly. Modify the
Battery Bar per FIGURE 11-01D/915iS. Remove Battery from Battery Box
assembly
INSTALLATION
8. Bolt Battery Box assembly to firewall.
9. Install Battery and Battery Bar. Install Small Cotter Pins to retain Battery Bar.
10.Refer to the ENGINE ELECTRICAL section for Battery Cable and routing.
EarthX Battery Box
1. Rivet nut plates to retainer clips.
2. Cleco the Battery Box Front Plate to the Battery Box Mounting Plate and Rivet
using two rivets as depicted in the parts drawing.
3. Fabricate four spacer bushings with the appropriate raw stock.
4. Mount the battery box to the firewall with the hardware called out in the parts
manual.
5. If there is any play between the battery and the battery box, the foam supplied
with the EarthX battery is there for a shim to tighten the fit up.
ROTAX 915iS - FUEL SYSTEM
(AFTER INSTALLATION OF ENGINE)
1. Refer to the parts pages and select the required components for assembly.

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RANS S-21 OUTBOUND TEXT MANUAL 14-6
INSTALLATION OF FINE FUEL FILTER TO FIREWALL)
NOTE: Fuel Filter comes with the engine.
2. Install the two AN fittings into the filter. Make sure to use the supplied copper
crush washers.
3. Mount the Fuel filter to the firewall in the location depicted in FIGURE 11-
01F/915iS.
4. Install the two firewall bulkhead fittings in the lower left-hand portion of the
firewall. See FIGURE 11-01G/915iS.
5. Install the fuel lines as per the parts manual and torque to the appropriate AN
value.
INSTALLATION OF FUEL PUMP AND COARSE FILTER
6. Transfer drill the fuel pump tray to the fuel pump tray support using a #40 drill bit,
cleco as you go.
7. Upsize the holes to #30, debur and rivet the tray support to the fuel pump tray.
8. Using ¼” edge distance, transfer drill the fuel pump tray to the two welded tabs
on the fuselage. These two tabs also pickup the aft portion of the pitch servo
tray.
NOTE: If an autopilot is not being used, it will take an additional fuel
pump tray and fuel pump tray support. These two parts, if used,
will rotate 180 degrees from the original parts. See FIGURE 11-
03/915iS.
9. Transfer drill the fuel pump tray support(s) to the fuselage belly skin and cleco in
position.
10.Remove the fuel pumps from the stainless steel ROTAX box it is mounted in.
Snip the pinch clamp bands and flip the fuel pumps upside down and attach to
the ROTAX fuel pump saddle using the appropriate hose clamps.
NOTE: Write the serial number of your fuel pumps down. They will
be upside down and hard to see later for inspection and service
bulletins during condition inspections.
11.Install two fittings to the fuel valve using thread sealant. Refer to FIGURE 11-
03A/915iS and the parts manual.
12.Remove the handle from the fuel valve and install the valve to the two tabs of the
fuselage steel frame. Use the mount brackets as shown in FIGURE 11-
03A/915iS. Re-install the handle to the fuel valve.
NOTE: Valve should be "ON" when valve handle is AFT and "OFF"
when valve handle is UP.
13.Install the fuel line from the valve to the fuel pump outlet. This will help locate the
fuel pump location.

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RANS S-21 OUTBOUND TEXT MANUAL 14-7
14.Build up the coarse fuel filter using the parts called for in the parts manual. The
filter itself is marked as inlet/outlet. Write the orientation of the filter on the filter
shell for future reference. Tighten all the fittings.
15.Install the fuel filter to the fuel pump inlet. Also install the fuel line from the
header tank outlet to the fuel filter. This will also help locate the fuel pump on the
tray.
16.Find the optimum position of the fuel pump on the fuel pump tray and mark
where the studs rest. Remove the fuel pump and drill these four locations.
Remove the fuel pump tray and debur all parts. Reinstall the tray and rivet to the
belly skin and bolt to the welded tabs. Reinstall the fuel pumps using the
hardware called out in the parts manual.
17.Connect fuel lines from the fuel valve to the by-pass block to the outlet firewall
bulkhead fitting. From the return firewall bulkhead fitting to the by-pass block.
From the by-pass block to the fuel check valve (check orientation) and from the
fuel check valve to the return inlet of the header tank.
18.Connect fuel lines on the forward side of the firewall. From the outlet bulkhead
fitting to the fine fuel filter. From the fine fuel filter to the fuel inlet rail and from
the fuel outlet rail to the return bulkhead fitting at the firewall.
ROTAX 915iS – HEADER TANK ASSEMBLY
1. Locate Header Tank Mount per FIGURE 11-03B/915iS. Transfer drill #30
through each tab. Glue Rubber Edging to top edge of Mount flanges. Rivet
Header Tank Mount to top of tabs.
2. Locate and drill fitting holes in Header Tank per FIGURE 11-03C/915iS. Do NOT
drill the sump drain holes until fitting of the tank to the fuselage. For drilling
the holes, a 1/2" Unit-Bit®and 3/4" Unit-Bit® work best. Locate center of each
hole with a #30 drill bit, then drill full size. Deburr all holes. Thoroughly clean tank
several times by using a shop-vac and then rinsing with water. After confirming
that all foreign material has been removed, let dry prior to installing fittings.
NOTE: If it is anticipated that the plane will be converted between
Trike and Taildragger, then it is recommended to install sump
drains in both locations.
DOUBLE & TRIPLE CHECK HOLE LOCATIONS BEFORE DRILLING.

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RANS S-21 OUTBOUND TEXT MANUAL 14-8
3. To install the fuel fittings into the tank, obtain a piece of wire. Safety wire works
well. Insert wire through one of the fitting holes in the tank and up through the
filler neck. Refer to FIGURE 11-03D/915iS. Install an O-Ring onto the tank
withdrawal fitting and slide this assembly over the wire extending from the filler
neck. Bend a loop in the end of the wire to keep the fitting and O-Ring from
falling off. Pull the fitting through the hole. Slide a flat rubber washer, thick steel
washer, and a retaining nut over the wire and onto the fitting. Apply Loctite to
threads, install the nut on before removing the wire.
CAUTION: Do NOT get Loctite on the rubber washer.
4. Use an Allen wrench inserted into the tank fitting to hold the fitting while
tightening the retaining nut.
IMPORTANT: Do not allow the fitting or thick washer to rotate while
tightening or leaks may occur.
HINT: Prevent the thick washer from turning by holding with
needle-nose Vise-Grips.
5. Apply thread sealant to fittings and install into the tank fittings. Again, allow no
rotation of the tank fitting. Refer to the parts manual for the correct parts.
6. Perform a leak test by capping off all fittings and pressurizing the tank to 1 PSI
and let set for a period of time.
CAUTION: Damage may result from over-pressurization. While the
tank is pressurized, check for any leaks by spraying a soap/water
mixture onto the tank and around the fittings. To cap off the fittings
use a 1" segment of fuel line with a bolt inserted, and fuel line
clamps or similar. An alternate test is to fill the tank with water and
let it sit for approximately 48 hours.
7. Modify Header Tank Mount Channel per FIGURE 11-03E/915iS. Position Header
Tank flush with front of Mount. Use large hose clamps to secure tank to mount.
NOTE: Modified Mount Channel will position under hose clamps,
on top of tank, and be positioned so that Channel ends are flush
with sides of header tank.
LOCATING HEADER TANK SUMP VALVE HOLE THROUGH BELLY SKIN
8. Mark on the outside of the tank on each side next to the sump valve as per
FIGURE 11-03F/915iS. This allows location of the hole through belly skin with
the tank installed.
9. Set the header tank in place. Transfer the marks on the tank to the belly skin.
Remove the tank and project the marked lines at 90° to the sides of the tank until
they intersect.

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RANS S-21 OUTBOUND TEXT MANUAL 14-9
10.Drill a #40 in the skin at the intersection. Set the header tank securely in place.
Drill #30 through the hole in the skin and the header tank. Use a step drill or
several sizes of drill bits to work up to the required size hole for the sump drain
fitting.
(AFTER WINGS MOUNTED TO FUSELAGE)
11.After wings are mounted to fuselage in final assembly, route fuel withdrawal line
from each wing and the fuel vent line from the left hand wing, down behind
Station 3 and to the header tank. Secure as desired using plastic ties. Add a
clear plastic tape or split fuel hose as anti-chafe wherever the lines contact the
fuselage frame or other parts.
OPTIONAL LOW FUEL WARNING KIT
1. Become familiar with the Optional Low Fuel Warning Kit on the Header Tank
PARTS MANUAL DRAWINGS and collect the parts shown in the drawings.
2. A 5/8" hole will need drilled in the side of the Header Tank. If not, refer to
FIGURE 11-03C/915iS. Replace Silicon Washer provided with Low Fuel Warning
Switch with 5/8" Rubber Washer. Install Low Fuel Warning Switch into Header
Tank. Be sure to orientate the switch to allow electrical continuity (closed circuit)
when installed. Use a continuity tester (Ohmmeter) to be sure. Refer to FIGURE
11-03G/915iS. As the header tank fills with fuel, the switch will open, turning off
the LED Indicator Light.
3. Install 5/8" Rubber Washer, 5/8" Steel Washer and plastic nut on outside of tank
and tighten. Double check to be sure the switch is orientated correctly.
4. Locate LED Indicator Light in instrument panel. Connect to Low Fuel Warning
Switch per FIGURE 11-03G/915iS. Do not forget to include a proper sized
breaker or fuse.
NOTE: Alternatively, the low fuel switch can be wired directly to an
EFIS as a discrete. This will allow you to not need the LED and
can be user inputted as a LOW FUEL WARNING!
ROTAX 915iS - COOLING SYSTEM INSTALLATION
(AFTER INSTALLATION OF ENGINE)
ASSEMBLY
1. Refer to the parts catalog and select the required components for assembly.
2. Attach the two oil cooler mounts to the gear box. Note the two spacer washers,
they are not used for Airmaster Propeller Installations.

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RANS S-21 OUTBOUND TEXT MANUAL 14-10
3. Install the top and bottom oil cooler mount plates and oil cooler bushings to the
oil cooler.
4. The AFT oil cooler bushing will attach to the FWD Radiator Mount Tubes.
5. Attach the FWD Radiator Mount Tubes to the Oil Cooler Bushings, through the
Radiator mount angles forward hole.
6. Install the AFT radiator mount tubes to the radiator mount angles, radiator and
the lower mount strap.
NOTE: If there is a bit of play in between the radiator and mount
straps, it can be shimmed using a RTV Silicone sheet or similar
material.
7. Install the Radiator Mount – Weldment to the case of the engine, using the
appropriate spacers and hardware.
8. Bolt the Oil Cooler/Radiator assembly to the oil cooler mounts previously
installed to the gear box.
9. Swing the oil cooler/radiator assembly back and bolt the radiator mount to the
radiator mount angles.
10.Safety wire all appropriate hardware.
(AFTER INSTALLATION OF OIL COOLER AND RADIATOR)
INSTALLATION OF COOLANT LINES
11.Remove the water pump inlet and install the water pump spacer kit. Orientate
the water pump inlet in the middle position, clocked pointing to the right of the
engine. Torque to 90 in/lbs.
12.Route the 1” radiator hose from the right of the radiator to the water pump inlet.
13.Cut the hose shortly after the radiator hose clears the engine mounts and install
the coolant springs and the radiator hose T.
14.Drill holes for the two bulkhead firewall fittings. See FIGURE 11-01I/915iS for
location. Install two coolant bulkhead fittings in the firewall. Loctite and tighten.
15.Route the 5/8” radiator hose to one of the two coolant bulkhead fittings.
16.Install the preformed radiator hose to the left-hand side of the radiator.
NOTE: This hose may require some trimming. Avoid any kinks in
any hoses.
17.Install the formed aluminum coolant tube and mount it to the exhaust pipe using
the hardware in the parts manual.
18.Trim a section off the preinstalled hose of the expansion bottle and insert the
second heater T. Use the trimmed of section to join the aluminum coolant tube
and the heater T.
19.Route a 5/8” radiator hose to the second bulkhead fitting.

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RANS S-21 OUTBOUND TEXT MANUAL 14-11
20.Install hose clamps on all lines.
21.Route the overflow hose from the expansion tank to the overflow bottle. Avoid
tight bends and kinks. Safety wire the hose to the expansion hose and to the
overflow bottle.
NOTE: There is usually a small mold line on the nipple of the
coolant overflow bottle that may need sanded smooth, if not this
can be a source of a small leak.
RADIANT HEATER INSTALLATION
22.On one of the dual fan heater mounts, install the fan speed controller.
NOTE: the RTV silicone called out on the parts manual. Tape a
dam around the backside of the controller and fill it with RTV
Silicone. This is to create a barrier between the electrical
components and the metal of the mounting plates.
23.Install the bolts from the fan side of the mounting plate, through the fan speed
controller. Snug the hardware, but DO NOT overtighten as this could break the
controller.
24.Assemble the fans to the Dual Fan Heater Mounts. The fans will have arrows
showing the direction of airflow and the rotation. Make sure the airflow arrow is
pointing away from the Heater Core. Attach the dual fan heater mounts using
Truss Head Screws. The screws will self-tap into the plastic housing of the fan.
Orientate the fans so the wires come out on the opposite side of the Heater Core
inlet/outlets. Attach the heater core to the dual fan heater mounts on top of the
fans. Tighten all hardware.
CAUTION: Do not overtighten screws into the plastic! Do not use
Loctite in plastic!
25.Install the two 90-degree Swivel fittings into the heater core.
CAUTION: When working with the Heater Core, be careful not to
over-tighten, or cracking may result. When tightening the fittings, it
is necessary to use a wrench to support the fitting on the cooler
itself.
26.Mount the radiant heater assembly to the welded cage using the cushion clamps
and hardware depicted in the parts manual. Position with clearance between the
firewall and the swivel fittings.

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RANS S-21 OUTBOUND TEXT MANUAL 14-12
27.Route the 5/8 heater hoses to the lower firewall bulkhead fittings. Make sure to
route the hoses in a way to ensure adequate clearance between the hoses and
rudder pedals. Trim the preformed hose from a “S” to a 90 degree. Use this
section on the left fitting of the heater core to the Control valve. From there it will
be a straight shot to the bulkhead fitting. Orientate the control valve so you can
access the control arm. Route the hose on the right-hand side in a straight shot
from swivel fitting to bulkhead fitting. Operate the pedals to assure clearance
between the pedals and the hoses. If needed, tie the hoses together with Plastic
Ties.
IMPORTANT: Double check to be sure there is no interference
with Rudder Pedals.
28.Locate the Control Valve in the Heater Hose attached to the Tee in the line
coming from the Expansion Bottle. Locate the Valve in a location that allows
connecting of the Control Cable.
IMPORTANT: Make sure you are installing the Control Valve in the
"HOT" side connected to the Expansion Bottle on top of the engine.
29.Locate the Control Cable, fan switch and rheostat in the instrument panel. Keep
this in mind when planning your instrument panel layout.
30.Route the control cable to the control valve. Mark it where the clamp of the
control valve is. Pull the control cable out several inches and trim the control
cable housing. Reinsert the control cable.
31.Drill #40 the center of the Valve control arm post. After retaining the Control
Cable housing in the clamp on the Valve, bend the wire to retain it to the valve
post. It must be bent in a tight loop around the post. The easiest way is to start to
wrap it around, bend it into a hook shape. Slip it off the post and use a pair of
pliers to hold it while completing the loop with needle-nose pliers. Twist it tight so
it fits snug over the post. Secure with #6 Pan Head Screw, stainless steel washer
and small brass washer. Trim the control wire after connecting. Check the
control wire and housing for a secure installation. Any movement of the housing
will reduce the travel stroke. If the valve cannot fully open and close,
performance of the heater will be diminished.
32.Connect wires to fan. Route them to the switch and power source.
33.After final engine install, check for coolant leaks and proper operation during
engine test run.
34.The heater should produce noticeable heat within a few minutes of starting the
engine. Depending on how well your cabin is sealed, and the outside air
temperature, the heater should be able to keep the cabin warm enough for
extended flying on winter days, or at altitude. Do not expect the heater to keep up
if you have many air leaks in your cabin, or if it is extremely cold (below 20
degrees F.).

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RANS S-21 OUTBOUND TEXT MANUAL 14-13
INSTALLATION OF OIL LINES
35.Oil Tank should be installed to center of firewall. See FIGURE 11-01J/915iS for
location.
36.Oil Breather Tube is installed on Firewall. See FIGURE 11-01K/915iS for
location.
37.Locate the applicable parts from the parts manual.
38.Install the two oil cooler adapters with gasket rings. CAUTION: Make certain the
gasket rings are in place or they will not seal. Torque to the appropriate AN
value.
39.Route all the oil lines in accordance with the parts manual. Be certain to avoid
sharp bends or kinking the lines. On the oil line from the pump to the tank, you
will need to use the banjo bolt that comes with the oil line, not the one that is
supplied by ROTAX, it does not have enough thread to be used with the fitting on
the supplied oil line. Torque all fittings to AN value.
40.Route the oil breather tubing from the oil bottle to the breather tube located on
the firewall. Trim the line to fit your installation. Safety wire to the oil bottle and
to the breather tube.
PRE-ENGINE START UP
Refer to the ROTAX 915iS Installation Manual for their specific
instructions on filling with oil and purging the oil system before
engine startup.
ROTAX 915iS – INTERCOOLER INSTALLATION
AIRBOX ASSEMBLY
1. Gather the parts needed to assemble the airbox for the intercooler.
2. Starting with the top or bottom air scoop cover and the inboard air scoop, line the
aft edges up. The inboard air scoop will go inside of the bent flange of the top
and bottom cover.
3. Once lined up and with the bent edge of the inboard air scoop facing forward and
the bend going towards the engine, begin transfer drilling #30 the tab holes of the
top/bottom cover, to the inboard air scoop. Cleco as you go. It will take a solid
push to press the inboard air scoop into the curvature of the top/bottom cover.
HINT: A vertical positioned 2 x 4 clamped into a vice makes
for a good tool to push on the air scoop while transfer drilling
the holes.
4. After either the top or bottom cover is transfer drilled and clecoed, proceed to the
other cover. Transfer drill and cleco.
5. Install the Air Scoop Attach Brackets to the intercooler. Ideally, they will fit with
the bolts being centered on the slots. Lightly tighten the hardware.

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RANS S-21 OUTBOUND TEXT MANUAL 14-14
6. Remove the 1st two clecos from the top and bottom cover on the aft edge and
slide the attach brackets between the top/bottom cover and the inboard air
scoop. Transfer drill the attach bracket holes to the airbox assembly. Cleco as
you go.
7. Cleco the Outboard air scoop to the air scoop attach bracket and rivet.
8. Remove the inboard air scoop, attach bracket and top/bottom covers from the
intercooler. Debur these holes and rivet.
INTERCOOLER MOUNTING
9. The intercooler mounts to the engine mount via cushion clamps and 3 different
brackets, two of which will require fabrication/modification. Starting with the
support angle, fabricate this attach bracket as shown in FIGURE 11-05/915iS.
10.Locate the support angle on the engine mount as shown in FIGURE 11-
05A/915iS. Mark and drill the holes into the support angle where the cushion
clamps line up on center line. Bolt the support angle in place and then hand
tighten one 6mm bolt through the support angle and into the intercooler.
11.Next, install a cushion clamp on the engine mount that will attach to the
intercooler upper mount strap. The upper mount strap will need twisted to help
align to the cushion clamp and the intercooler. This can be achieved by
clamping in a vise and using a pair of smooth jaw pliers.
NOTE: Use a set of soft jaws in your vise as well to keep from
damaging the strap. Once clamped in the vise, twist the part with
the smooth jaw pliers until the fit is right.
12.Check the positioning of the intercooler, use FIGURE 11-05A/915iS to determine
if any repositioning is needed. The cushion clamp that is attached to the upper
mount strap can be repositioned and the strap can be bent a bit more or unbent
slightly if needed. Hand tighten the 6mm bolt into the intercooler.
13.Once satisfied, move onto the third and final attach point. Install the cushion
clamp to the engine mount, attach the lower mount strap to the cushion clamp
and then hand tighten the 6mm bolt to the intercooler.
14.After checking the position of the intercooler after all the attach points are in
position, tighten all the hardware, except the 6mm bolts. Remove the inboard
6mm hardware, insert the inboard air scoop into position, reinstall the hardware
and hand tighten.
15. Remove the top outboard 6mm bolt and slide the outboard air scoop into
position, reinstall the hardware and hand tighten.
16.Lightly tighten the 6mm hardware with a wrench.
CAUTION: Do not over torque, the intercooler is made of aluminum
and the lugs can break off with over tightening.

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RANS S-21 OUTBOUND TEXT MANUAL 14-15
TRIMMING THE AIR SCOOP
17.After the cowling is fit up to the boot cowl, the two halves will be joined on the
intercooler itself. This will allow you to position the outboard air scoop up tighter
to the cowling. The top and bottom cover of the inboard half will pull up tight to
the intercooler. The top and bottom cover will require trimming to fit to the
cowling, leaving a small gap for the trim lock to make the seal to the cowling.
The bottom cover will require more trimming than the top.
18.With the lower cowling on, pull the covers over to the cowling and mark for
trimming, use a pair of hand shears and trim the cover.
NOTE: This may need to be done a few times to get it right. The
top and bottom cover’s aft edge will pull all the way to the
intercooler.
CAUTION: Measure twice and cut once.
19.Once the top and bottom covers are trimmed to fit the side of the cowling, the
outboard air scoop can be pulled over to the cowling along with the top and
bottoms covers for a nice, tight fit, leaving about 1/8” gap for the seal. Transfer
drill the holes of the outboard air scoop to the top and bottom cover. Debur and
rivet.
20.The intercooler airbox can be painted if you desire. After assembly or paint, cut
lengths of the trim-lock cushion lip to fit the top and bottom cover, as well as the
outboard air scoop’s vertical edge. There is no need for the seal on the forward
edge of the inboard air scoop.
INDUCTION SYSTEM
(AFTER INSTALLATION OF INTERCOOLER)
21.After the intercooler is mounted, you will need to trim silicone hoses and metal
tubing to fit the induction system. Be diligent in not wasting any of the silicone
hose. Cut all the silicone hoses as per FIGURE 11-05B/915iS. The larger drop
off pieces from the 90-degree elbows will be used as well, do not discard.
22.To cut the reinforced silicone hoses, use a sharp razor blade and one of the
supplied hose clamps. Slide the hose clamp onto the silicone hose and measure
from the end of the hose to the edge of the clamp. The edge of the clamp will
serve as a guide to help keep your cut edge straight. Tighten the clamp. Lightly
cut around the hose, do not cut all the way through in one pass, this will be more
difficult to cut straight. You can also clamp a small piece of the metal intercooler
connecting tube inside of the silicone hose, this will help the silicone hose from
collapsing from pressure while cutting.
CAUTION: Do not cut all the way through with the metal tube inside
the silicone hose, you will damage the metal tube and your razor
blades edge. Remove the metal tube before making your through
cut.

09/11/2018
RANS S-21 OUTBOUND TEXT MANUAL 14-16
23.A bandsaw also works to cut through the silicone hose, but you will not have as
straight of edges, and it is also messy. If you use this method, BE CERTAIN to
clean out the inside of the hose before installation.
24.Cut the metal intercooler connecting tubes from the raw stock. Use the lengths
called for in the parts manual. Work your way from either the intercooler or the
engine and connect the tubing and hoses as you go. Install clamps and tighten
them down once happy with the fit.
AIR FILTER INSTALLATION
25.The air filter is remotely mounted off the turbo. This is done to isolate the air filter
from the heat and potential vibration. The air filter will orientate aft. Trim the 60-
degree silicone hose as depicted in FIGURE 11-05B/915iS.
26.Slide the air filter connecting tube into the air filter, just enough that the tube is
flush on the inside with the mounting flange of the filter. Install a hose clamp.
27.Slide the connecting tube into the 60-degree elbow and install a hose clamp.
28.Last push the assembly onto the turbo and install a hose clamp. Orientate the
filter assembly from rubbing on any components. Check that the filter does not
rub on the edge of the cowling.
ROTAX 915iS - THROTTLE CONTROL ASSEMBLY
(FINAL INSTALL OF ENGINE)
ASSEMBLY
The engine needs to be installed to the airframe.
Instrument Sub-panel must be installed.
1. Refer to the parts catalog and select the required components for assembly.
2. Drill a 1 1/8” hole in the firewall for the throttle eyeball fitting in the location
depicted in FIGURE 11-01L/915iS.
3. Drill the hole of the throttle eyeball fitting to the diameter of the throttle cable
housing. This is easily done by leveling the internal portion of the eyeball fitting
to the housing of the fitting, tightening the nut, and then clamping the whole unit
in a drill press.
4. Install the eyeball fitting in the firewall and Loctite in place.
5. Remove lock washer and retaining nut from Throttle Cable Assembly.
6. Route Cables through center hole in Instrument Sub-panel. Secure with lock
washer and retaining nut.
7. Route cable through the eyeball fitting to the throttle body. Route to avoid tight
radii.

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RANS S-21 OUTBOUND TEXT MANUAL 14-17
8. Install the adjustable cable ferrule into the throttle cable mount on the engine,
next to the throttle body control arm. Route the cable to the ferrule and mark for
trimming if needed.
NOTE: The Throttle Control can be pulled out slightly to allow for
trimming of the Control Cable housings. Pay particular attention to
the literature that comes with the throttle control on removal of the
throttle pushrod.
NOTE: The throttle cable housing may require trimming the sheath
away to fit in the ferrule, this is ok. Just use caution while cutting
the sheath, the liner is strong, but avoid unnecessary cuts into it.
9. Insert the throttle cable housing into the ferrule and safety wire to the ferrule.
Also, safety wire the ferrule to the throttle cable mount. Route the cable through
the throttle body control arm cable clamp. Adjust the throttle for wide open
throttle, leave approximately a ¼’ gap between the throttle knob and the throttle
control housing. This helps to ensure that you can reach full throttle when
pushed in all the way.
10.Tighten the nut on the throttle body control arm cable clamp to hold onto the
cable. Trim excess cable and crimp on the end cap.
NOTE: http://www.rotax-owner.com/ has many E-Learning videos
available.
ROTAX 915iS - COWLING ASSEMBLY & INSTALLATION
(FINAL INSTALL OF ENGINE)
The Engine, Prop Extension, Spinner Backing Plate and Boot Cowl must
be installed before installing the Cowling. If Firewall Forward was
purchased less prop, contact RANS Parts Department for the proper 1”
Prop Extension. Refer to Propeller Installation for part number.
1. Refer to the parts pages and select the required components for assembly.
2. Attach two 3/8” spacers to the flange of the Spinner Backing Plate. See FIGURE
11-07/915iS. A couple of 3/8” thick wood boards work well for this. Bolt the
Extension and Spinner Backing Plate to the engine prop hub.
3. Trim prop opening flange of upper and lower Cowls to 1". Trim joggle areas of
lower Cowl to 3/4". Trim open all the air inlets and the area of the lower trip lip.
We typically leave the radius, and trim just on or just past it, this is done for
cosmetic reasons. On the intercooler opening, trim just the forward face and
leave the “ramp” to the opening. Refer to FIGURE 11-07A/915iS. A Dremel tool
with a reinforced cut-off wheel works well for cutting. A drum sander and a block
sander work well for smoothing rough cuts.

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RANS S-21 OUTBOUND TEXT MANUAL 14-18
4. Apply two rows of 2” wide masking tape to the Boot Cowl aft of the cowling
joggle. You want approximately 4 inches of tape aft of the cowling joggle all the
way around the Boot Cowl.
5. Mark a line 3” aft of the joggle all the way around the fuselage.
6. Tape the lower cowling in position against the backing plate with 3/8” spacers.
Line the cowling up evenly with the spinner backing plate, the oil cooler and
radiator. Mark 3” forward from the line on the fuselage. This will place a line on
the Cowling directly over the joggle.
HINT: Reinforced packaging tape works well to hold the lower
Cowling while fitting up.
7. Trim the edges of the lower cowling to the marked line and tape back in place on
the fuselage.
NOTE: It is usually best to not cut on your line on the 1st cut. Cut
just short of it and put the cowling back in place, check your line
again, and then trim to your line.
8. Once satisfied with the placement of your lower cowling, drill #40 in four spots
where your ¼ turn fasteners will be on the lower cowling.
9. Slip the upper Cowl into place. The forward edge should touch the 3/8” spacers.
The forward end of the upper Cowl should be positioned to allow an undisturbed
flow of air off the Spinner Dome and should be centered side to side. Trim area
around Prop Flange Opening to allow Cowling to align with Spinner Dome.
IMPORTANT: Check to be sure the air openings appear level from
side to side.
10.Re-adjust as needed and re-tape in place. The sides of the upper Cowl will lap
over the lower Cowl until trimmed.
11.Mark and trim the upper aft edge of the upper Cowl to allow it to set into the
joggle.
NOTE: The sides of the Cowl will be marked and trimmed after the
upper Cowl is fit.
12.Tape forward ends of the Cowlings tightly together, check for proper alignment.
Re-adjust as needed and re-tape in place.
NOTE: You can drill #40 on the front by the inlets, from the top
cowl to the bottom cowl, to help hold the cowling against each other
tightly. Later these two holes can be filled with body putty and
never seen.
13.Apply 2” wide masking tape to the lower Cowling below the joggle. You want
approximately 2” of tape below the joggle all the way along the Cowling side.
Mark a line 1.5” below the joggle.
14.Tape the upper Cowling in position and mark 1.5” from the line on the lower
Cowl. This will be placing a line on the upper Cowling directly over the joggles.

09/11/2018
RANS S-21 OUTBOUND TEXT MANUAL 14-19
15.The upper Cowling may need to be trimmed again. Everything changes a little
when it settles in the joggle. Sand to final fit.
16.Measure and drill the positions for the fasteners #40 at the cowl to boot cowl
joggle and cleco. Then on the cowl-to-cowl joggle. See FIGURE 11-07B/915iS.
17.Transfer drill all holes to #11 and cleco.
18.Final trim all the openings.
19.Refer to FIGURE 11-07C/915iS. Mark the opening position for the Oil Check
Door on the upper side of the upper Cowl.
HINT: A Dremel tool with a reinforced cut-off wheel and small
sanding drum works well.
20.Position Reinforcement Rings with fastener holes towards aft edge of cowl.
Transfer drill the #30 perimeter holes and cleco in place. Center Maintenance
Hatch in opening. Align holes for 1/4-Turns and transfer drill #30 through hinges.
Cleco as you drill.
NOTE: Try to get the holes in the hinges all on a flat surface, if the
holes begin to drift into the radius of the hinge, it will pull very hard
on the oil door or the cowling and deform either part after riveted.
NOTE: Form the Maintenance Hatch and Reinforcement Ring to
better contour to the upper Cowling if needed/desired.
21.Rivet 1/4 Turn Receptacles to bottom of Reinforcement ring.
22.Cleco 1/4 Turn Receptacles through #11 holes to inside of Boot Cowl Strips.
Align and transfer drill #40 though Receptacles. Remove Receptacles.
23.Position 4 forward Nut Plates to inside of lower Cowling and the bottom of the
boot cowl joggle, temporarily retain with Truss Head Screws and transfer drill
#40. Remove Nut Plates
24.Step drill Receptacle holes to 5/16”. Refer to FIGURE 11-07D/915iS.
NOTE: Rivet holes in the cowling may be countersunk for flush fit.
IMPORTANT: The 4 forward most holes must remain #11 for the
#11 Screws.
25.Step drill the fastener holes to 1/4”. Refer to FIGURE 11-07D/915iS.
IMPORTANT: The 4 forward most holes must remain #11 for the
#11 Screws.
26.Trim aft edge of lower Cowling air exit per FIGURE 11K-28/912.
27.Paint Cowlings and Oil Access Door.