ZODIAC CH 640 Series
Rudder Assembly Manual
Double click on the photo's to enlarge.
Rev.0-Sept/01
This rudder assembly manual has been
organized to help the first-time builder assemble the rudder tail kit.
The rudder kit requires an estimated 16 hours to assemble, and provides
the builder with an excellent introduction to building the complete kit,
covering most of the skills and techniques needed to assemble the rest of
the aircraft kit (the rudder is basically a diminutive version of the
wing).
INTRODUCTION
Building your own aircraft is probably
going to be one of the most challenging and rewarding things you will do
in your lifetime: imagine, you'll be flying in an aircraft that you have
built yourself! Few people get the sensation and freedom of flying. Even
fewer also get the reward of flying a plane that they've built themselves!
The most difficult part of the project
will be getting started: Don't become overwhelmed. While it's true that an
aircraft is a piece of complex machinery, it is also very simple,
especially when building from a kit. It's normal that you may initially
become overwhelmed and confused, but your initial fears and concerns will
disappear as soon as the project starts coming together, and as you get a
better understanding of the construction. The ZODIAC CH 640 is a
well-designed light aircraft - using proven materials and simple processes and systems.
This RUDDER ASSEMBLY MANUAL has been
prepared as a supplement to the complete and detailed Drawings and Manuals
for the ZODIAC CH 640 series aircraft.
READ
THE ENTIRE RUDDER ASSEMBLY MANUAL BEFORE STARTING.
GETTING STARTED
READING THE ASSEMBLY INSTRUCTIONS: The
detailed Assembly Instructions have been prepared so that the complete
airframe may be built from the parts supplied in the kit. The drawings are
not to scale, and provided measurements are metric (millimeters). All the
required references are provided in the Assembly Instructions, but often
only once (this may require some cross-referencing). For rivet holes, do
not count the "X"s shown on the drawing: Either the pitch
(distance between holes) is specified, or the number of holes (rivets) is
specified. Updates to the Assembly Instructions are published in the
Zenair Newsletter (back-issues are available).
Read first:
- Required Tools
- Using Your Tools
- Before Starting
WORKING TOLERANCES: When assembling the
Rudder, the pre-formed parts fit together properly, but certain
tolerances must be observed. Always follow the specified dimensions as
closely as possible, but remember to be practical and use common sense
(you're building a well-designed light aircraft, not a jet fighter).
Follow these tolerances:
Double click on the photo's to enlarge.
TYPE
INCHES
METRIC
Rivet Spacing
+/- 1/8"
+/- 3 mm.
Assemblies
+/- 1/8"
+/- 3 mm.
Parts
+/- 1/16"
+/- 1.5 mm.
See the Design & Constructions
Standards Manual for detailed tolerances for the rest or the aircraft.
Edge Distance (e) = 3 X Rivet Diameter
(d)
EDGE DISTANCE:
When positioning rivets, you must provide proper "Edge Distance"
(the distance from the rivet or rivet hole to the edge of the material)
for structural strength: The edge distance should be about three times the
rivet hole diameter, usually approx. 10 mm. (with two times the diameter
the minimum acceptable edge distance):
Working with sheet metal:
Handle sheet metal parts with care. Sheet metal skins can easily be
damaged (bent or kinked) when handled. With larger skins, it is
recommended that two people handle them (one on each end).
Be careful with sharp corners and
sheet-metal edges. Be especially careful with children around sheet-metal
corners at eye level (workbench height).
Always wear proper protection when
working with power tools and around sharp sheet-metal parts.
Avoid scratching the material, but do
not worry about light surface scratches. On spars and longerons,
transverse scratches and nicks must be removed by filing and sanding
lengthwise to remove scratches.
Don't throw away cut-offs - you may
find a use for such parts at a later date, or you can use them as
"practice" pieces.
DRAWING AND MARKING:
Before drilling or positioning parts together, draw the position on the
part(s) and hole marks. Use a felt-tip marker to draw. Do not use a pencil
or pen. Use
a straight edge to mark straight lines. To draw lines along a rib flange,
it's often easier to simply use your hand (finger) as a reference, or you
can use a simple "marking" tool.
CORROSION PROTECTION:
The aircraft has been designed to minimize exposure to corrosion problems.
In the usual environment, no additional corrosion protection is required.
However, you may want to add corrosion protection, especially if you will
operate or store the aircraft near salt water and/or in a polluted
industrial area. To add corrosion protection, the internal structure must
be primed with Zinc-Chromate (Zn-Cr) primer. This must be applied before
parts are riveted together. In the kit, pre-riveted parts, such as the
wing spars, have been primed at the factory. NOTICE: If using
Zinc-Chromate primer, follow the primer manufacturer's directions.
Purchase
yourself some Zinc Chromate Primer from Aircraft spruce 877-4-SPRUCE.
Questions or problems as you're
building? Think your question or problem through. Often the answer and
solution is very obvious and logical. If you can't solve it yourself, feel
free to contact AMD with your questions.
Remember, it's best that you submit technical questions on paper: draw
us a sketch of your problem, and FAX or mail it to us for a prompt response, or call or email us.
You will need all the kit parts that
make up the rudder tail section: You will notice that the parts are
conveniently labeled for easy identification. The first three numbers
indicate the page number on which the part appears in the Drawings and the
last number is the specific part number as it appears on the Drawing:
Each assembly of the aircraft is broken
up into sections such as the Left Wing, Right Wing, Rudder etc..
Each section is detailed in the Inspection
Parts Lists (IPL). The IPL’s are used when assembling the aircraft.
The IPL lists the parts in the recommended assembly sequence, with parts
quantity, description and a sign off area. so that once you have installed
a part, you initial the one line. The IPL’s are unique to the CH 640 and
were originally designed for the FAA certified CH2000.
Double
click on the photo's to enlarge.
Drawings: Only five pages of the actual
Drawings are needed to assemble the rudder: 640-R-1 and 640-R-2 together, 640-R-3,
640-R-4, 640-R-5, 640-R-6 and 640-R-7
Note: the first drawing numbers 20- or
640- are assumed to be for the same aircraft.
Drawings List:
Inspect all the parts that make up the
rudder section. Notice that you can verify all part dimensions and
specifications against those shown in the Drawings (the drawings are
actual blueprints and not just assembly drawings). Make sure the parts are
in good shape, dry and clean (remove tape, labels, etc.).
HANDLE THE PARTS WITH CARE,
ESPECIALLY PRE-FORMED SKINS.
Please note that parts and hole
locations in the following photos may not be the exactly the same as the
parts you have or the drawings. When questioning, the drawings are
always correct. NOT the photos.
Positioning the Doubler Angles
(20-R-2-6) inside the SPAR (20-R-2-5)
The Doublers are reinforcements for the SPAR section, positioned inside the SPAR as shown on Drawing 640-R-2.
To start, mark center lines along the inside of the SPAR doublers (in the middle of the Doubler flange).
Mark hole positions as per drawing 640-R-2, STARTING AT THE BOTTOM.
Note: first hole starts 50 mm from the bottom of the spar. After that, there is one hole very 40 mm over a length of 400 mm. The next hole is 30 mm up, than 35 mm up, than 50 mm up, than three holes 40 mm apart etc.. (p. 40 means that there should be a hole every 40 mm or less).
Make sure that the nose rib location at the spar is marked and that there will be no holes in that areas.
NOTE THE LOCATION OF THE UPPER HINGE BRACKETS 20-R-4-2 ON DRAWING 640-R-5. The hinge brackets are located 510 from the bottom. There is a 10mm gap between them. Mark the area down on the spar and do not drill in that area.
Mark all the rib locations as per 640-R-5 before drilling the
spar doublers. Mark these areas clearly. Know where everything will be
before drilling the spar holes.
HINT ON DRILLING:
When drilling through an existing hole, avoid enlarging that hole. If you
find this to be a problem, consider under-sizing your first hole, and then
re-drilling it to proper size later. Also, don't press too hard
with the drill (this will minimize drill ‘travel’) and prevent the
part underneath from bending under the drill's pressure.
HINT ON MARKING HOLES:
When measuring the pitch (hole distance) along a straight line, start by
marking the first and last holes (with the proper edge distance at both
ends). Then proceed to mark the additional holes (in between the two end
marks) at the required pitch. Always try to keep the pitch consistent
(unless otherwise instructed): This may require adding or subtracting a
millimeter or two to the pitch. As a rule of thumb, it's better to add an
extra rivet than to spare one when making these slight adjustments to the
pitch. Remember, the "x"s on the Drawings do not always
accurately illustrate the number of rivets: Read the requested Pitch (or
specified number of rivets), and remember the required Edge Distance.
Remember to provide proper edge
distance.
Once you have marked each hole location, put the doublers beside each other and transfer the marker line to the other doubler, saving time measuring again.
Clamp the doublers in place.
Once positioned properly, drill the
marked hole locations into the SPAR (#30 drill). Repeat with other
doubler. After drilling every other hole, place a Cleco in the hole to
clamp the assembly together.
Cleco the parts as you drill. Use the cleco's as clamps to hold the assembly down flat on the bench.
HINT: Never worry about using too many Clecos. The more Clecos you use, the better your parts are being held together. However, you'll rarely need a Cleco in every hole.
HINT: Keep drill bits SHARP. The drill bit is probably dull if you find you
have to press too hard with your drill: sharpen or replace the bit.
Installing Rear Rib (20-R-6-1) to
the Spar (SPAR)
As shown on Drawing 640-R-5.
20-R-6-1 - Draw
a straight line 10mm parallel to the bottom spar edge. Mark
five (5) evenly spaced drill holes along the line (remember Edge
Distance). Holes in the flange (#30 drill). Also See 640-R-7 drawing detail
"Lower Rear Rib"
Drill the five holes.
Mark a center line on rib 20-R-6-1 flange with marker as shown.
Take the rib and position it inside the spar as shown. Through the drilled holes, locate the rib marker flange line so that the marker line is centered in the holes. The rib is now positioned. No measuring required!
Clamp the rib to the spar and drill into the rib through the existing drilled spar holes.
The other ribs are located using the same method. ie
- Mark the rib and hole locations on the spar and drill the rivet holes
- Mark a straight line on the rib flange
- Install the rib by lining up the rib marker line through the spar holes
- Clap rib to spar and drill through the pre-drilled spar holes
- Cleco as you drill
This photo shows the final installation of 20-R-6-1 with the skin, not to be installed at this time.
Positioning 20-R-6-2 and 20-R-6-3
and 20-R-6-4 to the SPAR
. See Drawing 640-R-5
Install the other ribs by using exactly the same procedure as 20-R-6-1.
20-R-6-2 :
As shown on Drawing 640-R-5, measure up 550 from the bottom of the spar
assembly, and mark
a straight line (perpendicular to center of SPAR) across the SPAR where 20-R-6-2
will be positioned.
Mark 3 rivet holes making sure that
they will be in the rib flange, and drill the 3 holes in the spar. See
640-R-4 drawing, rib #2,3 and 4.
20-R-6-3 is located 720mm from the bottom of the spar. 20-R-6-4 is located 1080mm from the bottom of the spar. Drawing 640-R-5 will give you the exact dimensions.
NOTICE:
The Ribs may require a little trimming to clear the spar doublers inside the SPAR
assembly. If required, trim lightly with hand snips, evenly
on both sides. Don't trim too much.
Positioning the Tip Rib 20-R-3-2
Take an L Angle (90 degree shaped angle, 4 feet long) and cut off 35mm. See drawing 640-R-4 Tip Rib.
Note: When cutting with the snips, always do a rough cut first. Then do a final cut which will be much cleaner. This will save a lot of filing time.
Take the tip rib 20-R-3-2 and mark the location of the L angles as per drawing 640-R-4 Tip Rib. It is located 50mm from the tip. Mark a line as shown.
Position the L angle to the rib and drill two holes. Note that the 50mm on drawing 640-R-4 Tip Rib is from the tip of the rib to the spar. Make sure that the L angles is properly located.
Now locate the same L angle to the spar tip as shown on drawing 640-R-4 Tip Rib.
Clamp, drill and Cleco the L angle in place.
Put the assembly together.
The Nose Rib is positioned 740mm from the bottom of the spar. Note that the flange is up at the spar.
- Mark the rib and hole locations on the spar and drill the rivet holes. five in total. One in each spar doubler and three in the middle.
- Mark a straight line on the rib flange
- Install the rib by lining up the rib marker line through the spar holes
- Clap rib to spar and drill through the pre-drilled spar holes
- Cleco as you drill
There is a Balance Mass (20-R-5-5) located on the front of
20-R-3-1. Locate, clamp and drill.
Draw center lines across all the rib
flanges and spar. These lines will be used l when positioning the skins over the
ribs.
The Upper Hinge Brackets (20-R-4-2) can now be installed as
shown on drawing 640-R-5. Note that the top of the bottom bracket is located at
510 mm from the bottom of the spar. The upper bracket is located 10 mm
above the bottom bracket as shown on drawing 640--R-5 and 640-R-4. Clamp and drill the
two brackets.
Photo's show a thick strap riveted to the spar by the Hinge Brackets. This is for lightning protection and should be installed later.
You have now completed the rudder
‘skeleton’ (internal structure). You
must now take the assembly apart (remove Clecos) and de-burr all the parts
(drilled holes, and material edges). If applying corrosion protection,
apply after de-burring.
Cleco the parts back together again, and rivet together. The rivet head always goes on the thinner material. You may find that the holes don't match up together exactly (the rivet may not want to fit in the hole) -- if this happens, simply re-drill the holes lightly.
Hint: Before taking an assembly apart (after having Clecod it together),
it's a good idea to mark where the parts are located, so that you can
easily put the parts together again. To do this, run a line or two (with a
marker) across two joined parts. When you want to put the parts together
again, simply realign the drawn lines.
HINT: To de-burr hard-to-reach place (where it's difficult to access both
sides with a large drill bit, use a flat file to file away any burrs.
POSITIONING THE RUDDER SKINS:
See drawing 640-R-5Since the rudder tail section tapers in
width (the rudder is wider at the bottom and narrows at the top), it is
important that when it lies flat on your workbench, the bottom trailing
edge section of the rudder be raised to compensate.
Take two straight 2x2 or 2x4 pieces of wood. Place one under the spar and the other under the trailing edge. Raise the bottom of the trailing edge up by about 3/4" as shown on the photo's. Failure to do so may force a "twist" in the rudder.
Remember to use the 3/4" wedge
each time you place the rudder flat on your workbench, especially when
drilling the rudder skins to the skeleton assembly, as this determines how
symmetrical your rudder will be.
HANDLE THE PRE-FORMED SKINS WITH
CARE. When working along the
trailing edge of the pre-formed rear rudder skin, do not squeeze trailing
edge, as this may force a permanent ‘kink’ in the material. If
applying pressure, apply over large area so not to damage skin.
Installing the two rear rudder skins (20-R-5-2 and 20-R-5-1) to the Rudder skeleton assembly.
Cut the two rear skins as per the
drawings. For the Lower Rear Skin, cut out the triangle at the bottom and
two small ones at the top, as shown.
Place the rudder skeleton assembly
inside the pre-formed rear rudder skins (lay flat on workbench), as shown
on Drawing 640-R-5, working on one side only. The Upper and Lower Rear
Skins are joined together at rib 20-R-6-4
NOTICE:
Handle skins with care - they are fragile and may dent with improper
handling. Handle formed skins by the radius (placing hands inside radius
at both ends, and lifting).
Locate 20-R-5-3 as shown in drawing 20-R-5. This channel goes between the two bottom ribs. The actual location of this channel locates the distance between the two ribs so that there is 125 mm between them. Drill the channel after the rear skin is clecoed to the ribs.
NOTICE:
The pre-formed skins are purposely supplied over-sized (when applicable),
and may require trimming of edges with hand snips.
The rear skins are pre-drilled for the ribs. The holes will give you the exact location of the ribs. You may have to move the ribs with your hands so that the ribs line up with the pre-drilled skins.
Line up the bottom of the rear skin to the bottom of the spar and 20-R-6-1
Draw a marker line on top of the rear skins so that it is in the center of the spar angle. Mark a hole pitch of 40mm starting at the bottom.
Remove the rear skins and drill the spar holes in the skins.
All holes on the skins are #30 (A4
rivets) p. 40
Mark the center line on the spar and ribs.
Re-install the rear skins and line up holes to the marker lines.
Drill through the pre-drilled holes in the skins, into the spar.
Now that the skins are clecoed to the spar, line up the rear ribs to the skins and drill. Cleco as you drill. Do not remove the cleco's at this time.
Turn the complete rudder assembly around and mark the center line of the ribs and spar.
Through the pre-drilled holes, drill the holes in the ribs starting at the trailing edge and move towards the spar.
Always make sure that the rudder is properly positioned on the wood blocks and that the bottom trailing edge is lifted by 3/4".
Drill the spar holes.
Remember to use lots of Clecos.
Note: installing the rudder skins is
probably the hardest area of the aircraft. Once you have mastered the
rudder assembly, you will have an excellent understanding of basic sheet
metal assembly.
When drilling near the trailing edge,
be careful not to press too hard (do not drill right into the other side
of the rudder).
For the TIP RIB and bottom rib, do not
use a center line on the rib flange: Position the skin edge just inside
(below) the rib radius for a nice finish.
HINT: Keep material firmly flat on your workbench (which must be straight
and level).
Installing the Nose Skin (20-R-1-1)
to the Rudder assembly
Keeping the rear skins Clecoed in
position, remove the cleco's at the spar.
For positioning purposes, slid the Nose Skin in-between the Rear Skins and the Spar, this is a helpful construction method to hold the Skin in place.
SUGGESTION:
You may find it easier to TAPE the skin in position, using a sturdy
"shipping" or "duct" tape, taping both ends of the
Nose Skin tightly to the Rear Skin, on both sides.
NOTE: When positioning the Nose Skin
make sure that the radius (leading edge) of the skin is positioned
directly across the leading edge (most forward) part of the ribs.
Make sure that the nose skin front radius is centered with the center of the nose ribs.
Note that the bottom nose rib, 20-R-3-1, is angled 90 degrees to the spar.
Once in position, drill the spar holes, through the pre-drilled holes in the rear skins. Cleco as you drill.
Turn the assembly around and repeat the above instructions. Nose skin should be tight against the nose ribs.
Drill holes in 20-R-3-1 nose rib.
Notice that the Nose Rib and Tip Rib
have been crimped (a crimp is placed on the flange to form the round edge
of a rib - the crimp takes up the excess material in the forming process).
When positioning the rivet holes it is important to avoid an area
that has been crimped.
Mark a single hole for the Tip Rib on
the skin, just beyond the crimped area on the Tip Rib, and mark 6
holes on the skin for the Nose Rib (pitch 40, avoiding crimped areas).
Install 20-R-5-4 fairing using same procedure as above. See drawing 640-R-5 section B-B for installation.
Note that the pre-formed Nose Skin is
supplied slightly oversized, and may require some trimming to provide a
nice finish.
Now inspect your rudder and make sure that all skin holes are drilled, including 20-R-5-3.
Take the skins off the "skeleton" assembly (remove Clecos), clean them, trim them, inspect the hole tolerances in the ribs spar and skins, deburr and corrosion protect.
Make sure that the Balance Mass 20-R-5-5 is installed at this time and properly bolted to the nose rib. Install wire for tail light at this time (optional - see 640-R-5 16 ga. wire). Photo shows cut-out at rear bottom trailing edge for tail light (option). This may be cut-out and installed once the rudder is finished.
Riveting the Skins to the Rudder
Assembly
You've now completed all the hard work!
Now, all you need to do to complete the rudder is to rivet the skins in place.
Cleco the skin parts back together
again, and rivet together. If you find that the holes don't match up
together exactly (the rivet may not want to fit in the hole) -- if this
happens, simply re-drill the holes lightly.
You can now install the Rudder Horn
20-R-7-1. Before installing, make sure that the shape is as per drawings.
Drill the holes in the Rudder Horn first. Now position the Horn to the
lower Rear Rib as per drawing 20-R-7. Note that the rivet size is larger.
Use the A5 rivets and rivet from the horn into The rib.
Congratulations!
You've now completed the rudder tail section, which is a significant
section of your own aircraft!