Subassembly 4: The Right Elevator
by Frank Justice
Items of particular interest in the right elevator assembly are:
the Wd-405 control horn bend angle and bend line, the E-609 root
rib flange bend line where it meets the E-602 spar, and the E-604
and E-405 tip rib flange bend angles and bend lines where they
meet the spar. The height of the flanges on the long sides of
the spar should be equal although they do not need to be exactly
5/8 inch. Taking care of these early reduces the twist in the
spar in the final assembly, thus making it easier to line up the
skin; it also insures that the two bearing rods are in alignment
with each other thus making the elevator align properly with the
horizontal stabilizer. Preliminary Parts Preparation
These preliminary operations are not all essential but if done
will cause many hours to be saved later and also help to improve
the appearance and aerodynamics of certain areas. It is easier
to do these all at once rather than as the parts are called for
in assembly. Since many of the elevator parts are the same for
both sides, it is convenient to do these operations on parts for
both at the same time. E-604 short tip rib:
Flute flanges to straighten. Bend all four flanges to be perpendicular
to the web. Notch part of flange to clear flange on E-602 spar;
hold it up to the spar to see how much to cut out. File down the
flanges to an even height (approximately 5/8 inches). Verify that
the flange on the trailing edge of the rib is perpendicular to
the centerline of the rib; carefully rebend if necessary. E-603 long tip rib:
Flute flanges to straighten. Bend all flanges to be perpendicular
to the web. No need to file flanges. E-609 right side root rib (same for E-605 left root rib):
If bend line of flange that mates with spar is not perpendicular
to the centerline of the rib, carefully modify the bend so that
the flange is perpendicular. This is important in that it guarantees
that the elevator will line up directly behind the horizontal
stabilizer. Then bend ths flange down to an angle of approximately
68 degrees from the web. If the flanges on the long edge are not
perpendicular to the web, bend them so they will be; then file
them to be equal in height. Drill two #40 holes 1" apart in the
flange for rivets that will later attach the rib to the spar.
If the bend line of the flange at the tip end is not perpendicular
to the centerline of the spar, carefully modify the bend so the
flange is perpendicular. This flange must also be perpendicular
to the web of the spar. Insure that the long flanges are fairly
even and of equal height. Radius the outside edge along both flanges
slightly to keep stress from building up in the skin which starts
its bend here for the leading edge. E-410 and E-411 reinforcing plates:
Drill #30 holes as shown in drawing 5a. Do not drill the holes
for the nutplates; drill a #30 hole at the center of the nutplate
location; locate this hole as accurately as possible to the long-way
centerline of the plates. Wd-405 control horn:
Verify that the bend angle is 68 degrees; if not, bend so that
it is. Drill the 12 #30 holes as shown in drawing 5a except that
the two holes next to the bend and the two holes in the center
on the side with the tube should be placed 1/4 inch farther from
the bend than shown in order to later clear the flange of the
root rib and the trim tab rib (on the left elevator only). Do
not drill the 1/4 inch hole in the horn. Locate the extended centerline
of the tube on the control horn and mark. (Put a narrow straightedge
inside the tube and align it with first one side and then the
other; draw the tube centerline halfway between these two lines.)
Tip Rib Assembly:
None of the rivet hole locations in this assembly are critical.
Clamp the two ribs together with the flanges carefully aligned.
Drill all the joining rivet holes shown in drawing 4a except the
ones for the counterweight baffles. Make the counterweight baffles
for the tip ribs as shown in 4a, including the mounting holes.
Clamp the baffles in position and drill their mounting holes into
the rib assembly. Drill the two holes 7/32" for the counterweight
hold-down bolts. Prime the surfaces of the ribs and the baffles
where they mate and rivet this assembly together. E-613 counterweight skin:
Hand-bend the counterweight skin so that it will conform to the
tip rib assembly with only moderate hand pressure, then clamp
it on with the edge of the skin aligned with the edge of the flange
of the inside tip rib E-604. Drill #40 and countersink all the
rivet holes that will not be later covered by the skin; see drawing
4a. There should be 28 holes. Remove counterweight skin from tip
rib assembly. Making Stiffeners and Laying out the Skin
Building the Spar and Skeleton of the Right Elevator
- (objective paragraph as in construction manual)
- Lay out the position of the elevator skeleton and the stiffeners
on both inside faces of the skin. Use sketch SK6-2. Also note
the 1/8" overlap and alternation of flange position between sides
for the stiffener placement shown on drawing 4a. Do not trim skin
- Fabricate the stiffeners from the 5/8"x5/8"x.025" angle provided.
See dwg 4a to determine shape and distance from ends to spar and
- Lay out the centerlines and rivet positions on the stiffeners.
Position them on the skin; holding them down with duct tape is
adequate. Drill them #40 to the E-401 skin as you did the rudder.
Debur and dimple.
(read objective paragraph in construction manual) Alignment and Error Check:
Assembling the Skeleton
- Clamp the E-609 root rib, Wd-405 control horn, and tip rib assembly
to the ends of the E-602 spar. Insure that the centerline of the
control horn tube coincides with the centerline of the spar. Lay
this assembly on one side of the skin against the marks for the
spar and the longer tip rib; verify that the root rib winds up
approximately in its proper place. (SK6-2 shows the root end of
the spar going all the way to the end of the skin but it should
actually be shown as ending even with the web on the root rib.
At the tip end the rib shown is actually the back half only of
the longer tip rib E-603; the inside short rib E-604 is not shown.)
Then, hold this assembly up to the right side of the horizontal
stabilizer (HS). Clamp the control horn to the center bearing
of the HS with one AN960-416 washer in between. On the tip end
there should be a space 1/8" to 1/4" between the elevator tip
rib and the HS tip rib. If not, reposition the control horn on
the spar (and trim that end of the spar if necessary).
- Verify that the control horn tube still coincides with the centerline
of the spar, and match drill the six control horn holes to the
spar. Insure that the root rib is still in proper position against
the spar and the control horn and mark through the two rib flange
holes onto the spar. Remove the control horn and drill #40 holes
at the marks on the spar. Countersink these holes on the side
away from the rib. Put rivets into these holes held on with thin
tape to keep the rib and spar aligned. Reassemble the control
horn and root rib to the spar and match drill the six control
horn holes into the rib.
- Drill two #30 holes through the spar and the E-604 tip rib flange,
then drill two #30 holes through the E-603 into the flange of
- Position this assembly against the horizontal stabilizer as before
and verify the 1/8" to 1/4" space between the tip rib and the
HS tip rib. If not quite correct, another washer or two may be
added or the elevator tip rib flanges may be shaved as applicable.
Mark the position of each pair of HS hinge brackets accurately
onto the elevator spar. Drill #30 holes on the centerline of the
spar halfway between each pair of marks for the hinge brackets.
Position the E-410 and E-411 on the spar with a cleco through
the center hole and clamp firmly. Match drill the reinforcing
plate holes into the spar. Enlarge the center hole to 3/8". Put
a nutplate in place over the hole and secure it by inserting a
rod end bearing with a nut on it from the other side. Drill the
two nutplate mounting holes.
- Disassemble everything, debur, and prime.
Finishing the Skin
- Rivet the reinforcing plates and nutplates to the spar.
- Rivet the root rib to the spar.
- Rivet the control horn to the spar and the root rib.
- Rivet the tip rib assembly to the spar.
- Backrivet the skin stiffeners to the skin.
- Complete the trailing edge bend.
- Recheck the skeleton rib positions against the skin markings;
align the tip rib flange edge with the its mark 1/2" from the
trim line for the edge of the skin. Verify that the inside edge
of the tip rib is perpendicular to the spar and remark the tip
trim line if necessary. Remark the trim line at the root end if
necessary to keep it even with the edge of the flange. The old
spar position markings on both the left and right sides of the
skin should line up with the spar at the same time. If not it
is because the trailing edge bend finish operation tended to favor
one side. In this case remark the lines on the skin.
- Mark the approximate position of the centers of the rod end bearings
onto the outside of the skin. Using this as a reference point,
mark the 2" bearing access cutouts centered on a point 1/4" toward
the root from the rod-end bearing centers on the outside of the
skin so the opening can be made after the leading edge is formed;
cutting them out here makes it more difficult to form the leading
edge bend and does not save any work. Mark the position of the
inside edge of the short tip rib on the skin; mark the small triangular
cutoff at the root end. Trim the skin at these cutouts and along
the tip and root rib marks.
rtelevtr,doc 1/14/94 Frank Justice
- Set up the root and tip Elevator V-block jigs on a flat surface
(the center V-block is not needed for the right elevator). Insure
that the "V" of both blocks is exactly vertical to avoid twist
in the finished elevator.
- Place the skin and skeleton together in the V-blocks; clamp the
skeleton firmly to the skin, insuring that the inside edge of
the short tip rib is exactly perpendicular to the spar. Cleco
the counterweight skin in place to the tip ribs. Note that the
counterweight skin ends go under the main skin.
- Determine the skin to skeleton rivet spacing and drill #40. Also
drill two holes on both sides through only the skin and counterweight
skin as shown in drawing 4a (where it shows CS4-4 rivets; with
these directions you will use AN426AD3-3.5 rivets instead and
impress your friends).
- Mark a line on the counterweight skin that is an extension of
the tip edge of the main skin.
- Disassemble and debur. Countersink the new holes in the counterweight
skin. Trim the counterweight skin on the line drawn in the previous
step. Dimple all the skin and skeleton holes except the ones in
the tip rib assembly where the counterweight skin sits. Touch
up with primer applied thinly with a q-tip to avoid upsetting
the countersink/dimple depth.
- Rivet the counterweight skin to the main skin with only the four
AN426AD3-3.5 rivets mentioned above.
- Put the skeleton back into the skin in the V-blocks and rivet
together. Be sure to check that the rivet size is correct for
each section by actually measuring them.
- Complete the leading edge bend of the E-601 skin. Dimensions are
given in the Elevator Leading Edge Detail of drawing 5a. See procedure
R-9 for the technique. Be careful to avoid having the skin bend
sharply at the front edge of the spar flange. A heavy length of
pipe 1/2" to 3/4" seems to do the best job, and duct tape holds
the skin to it quite well. When marking for the rivets remember
the 2" wide cutouts at the bearing access locations.
- Make the initial bearing access cutouts in the leading edge; they
should be 2" wide on the bottom side and up just enough on the
top side to allow the rod end bearing to be put in; the rest of
the top side should be just wide enough to clear the horizontal
stabilizer brackets. The opening should go about halfway back
from the leading edge to the flange of the spar. The openings
shown in the plans are larger than they need to be and slightly
- Install the rod end bearings in the spar and install the completed
elevator on the horizontal stabilizer with bolts through the HS-412
and HS-413 hinge brackets. Check the spacing from elevator to
horizontal stabilizer as shown in drawing 5a. Then verify that
the elevator will go up by about 30 degrees and down by 25 degrees
before hitting the stabilizer skin. If necessary, turn the rod
end bearings in or out to obtain the proper spacing, then lock
the bearings down with the nuts. Secure the elevator with the
counterbalance arm aligned with the horizontal stabilizer end.
Drill the bearing bolt hole in the Wd405 control horn using the
HS-411 bearing as a template.
- Hold the pouring of the counterweight lead until the left elevator
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