09/11/2018
RANS S-21 OUTBOUND
TEXT MANUAL
11-23
ROTAX 912 ULS - 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 11K-02/912.
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.
Set both upper and lower cowls on their aft edges on the floor. Match the cowling
together to determine where to trim the lower cowl’s forward edges to match to
the upper cowl. Trim prop opening flange of upper and lower Cowls to 1". Trim
joggle areas of lower Cowl to 3/4". Refer to
FIGURE 11K-03/912
. A Dremel tool
with a reinforced cut-off wheel works well for cutting. A drum sander works well
for smoothing.
4.
Remove AFT flat section of Radiator inlet area of lower Cowl. Refer back to
FIGURE 11K-03/912
.
HINT:
Use a black sharpie to mark the cut-out perimeter.
5.
Apply two rows of 2” wide masking tape to the Boot Cowl aft of the cowling
joggle. You want approx 4 inches of tape aft of the cowling joggle all the way
around the Boot Cowl.
6.
Mark a line 3” aft of the joggle all the way around the fuselage.
7.
Tape the lower cowling in position against the backing plate with 3/8” spacers.
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.
8.
Trim the lower edge of the lower cowling to the marked line and tape back in
place on the fuselage.
NOTE:
The sides of the cowl will be marked and trimmed after the top
cowl is fit. Leave the aft edge of the scoop exit long for now.
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.
