SECTION 10
ENGINE MOUNT, WHEELS, BRAKES AND FAIRINGS
RV-8/8A
10-3
8-s10r9 7/11/11
When all the connections in the brake system are tight and checked, fill the brake system with fluid.
NOTE:
USE ONLY THE CORRECT AIRCRAFT BRAKE FLUID!! USING AUTOMOTIVE SILICONE BRAKE FLUID
WILL DAMAGE THE BRAKE SYSTEM IRRETRIEVABLY!! You
don’t
want to do that....
The system is filled and bled from the bottom up. A small, clean, pump can is connected to the bleed nipple on the
bottom of the brake assembly with a soft plastic tube. The nipple is opened a turn or so and fluid is pumped up
through the lines and master cylinders to the reservoir, pushing air out of the lines ahead of it.
INSTALLING RV-8 GEAR LEG FAIRINGS
Gear leg fairings on the RV-8 are installed in two phases. The first phase is the fitting of the fairing to the gear leg.
The second phase is the custom molding of intersection fairings between the gear leg fairing and the fuselage at the
top of the gear leg and between the gear leg fairing and the wheel fairing at the bottom of the gear leg. The first
phase may be done on a completed aircraft, but is more easily completed with the gear legs off the airplane and
resting on a workbench. The second phase must be done with the gear legs and fairings installed in their final
position on the airplane with the wheel fairings installed.
Start by trimming the ends of the fairings to the molded-in scribe lines. The trimmed fairings should be 25 15/16
inches long.
Place the fairings over the gear legs. Hold the fairings closed at the trailing edges with light spring clamps or
adhesive tape. Avoid distorting the natural shape of the fairings with excessive clamping pressure. With the trailing
edges taped or clamped closed, wiggle the fairings around on the legs to find the point of best fit. The inside contour
should snugly fit the gear leg, and there should be no localized distortion due to a “too tight” fit on the gear leg. If the
fit of the fairing to the gear leg is too loose, move the spring clamps forward on the fairing. If the fit of the fairing to
the gear leg is so tight that the fairing is distorted, move the spring clamps aft. The optimum position for the spring
clamps is slightly tighter than when the fairing inside contours just “capture” the gear leg. This slightly tight fit
provides for a small pre-load holding the trailing edge of the fairing tightly closed
Trim “HINGE PIANO 063” hinge material to 26 inches long, one piece for each fairing. Trim the hinge pins to 28
inches long. Use a “Sharpie” pen to mark (but do not drill) fastener locations on each of the hinge segments.
Fastener spacing is shown on DWG 50. When drilling the hinge to the fairing, the fastener location marks will be
visible through the translucent fairing.
Position the marked hinge inside the trailing edge of the fairing as shown on DWG 50, Sections B-B and C-C.
Clamp the hinge ends in place and drill #40 through the fairing and hinge using the marked fastener locations on
the hinge to position the holes. Work from one end of the fairing to the other, clecoing each hole before drilling the
next.
Remove the clecos from the hinge and fairing. Clean out any metal chips, de-burr holes, and countersink the fairing
for AN426AD-3 rivets. Attach the hinge to the fairing using the rivets called-out on DWG 50, View A-A. Use a hand
squeezer when installing the rivets. Do not fully set the rivets to the same size as you would if you were riveting a
metal structure. Rivets squeezed to that size will cause cracking in the material around the holes in the thin, non-
structural composite fairing
Insert the hinge pin to close the fairing. Trim the trailing edge of the fairing to remove any excess “tail” on the fairing.
Use a long sanding block (or several pieces of sandpaper glued/carpet taped to a flat surface) to square and true
the trailing edge.
Bend a ½ to 1 inch long 90º bend on the lower end of the hinge pin. File the upper (straight) end of the hinge pin to
a rounded or “bullet” shape to help guide the pin through the eyes of the hinge during fairing installation. Drill a #40
hole in the upper surface of the lower end of the fairing through which a piece of safety wire can be looped to hold
the hinge pin in place. See DWG 50, View A-A.
For final installation, the fairings are slipped over the gear legs, positioned, and the hinge pin is inserted from the
bottom of the fairing. The pin may be bent as it is inserted without the pin taking excessive permanent bend. There
should be some means of preventing chafing between the gear leg and the inside of the fairing. Wrapping the gear
leg with wear resistant plastic adhesive tape prevents chafing as well as holding the brake line in place.
Use the clay male-mold process described in “Intersection Fairings” to create intersection fairings between the gear
leg fairing and the fuselage and between the gear leg fairing and the wheel fairing. The intersection fairing between
the gear leg fairing and the fuselage should be attached to the fuselage with approximately four #6 countersunk
screws spaced around the perimeter of the intersection fairing. Screws may be installed through non-structural
RV-8/8A
SECTION 10
ENGINE MOUNT, WHEELS, BRAKES AND FAIRINGS
10-4
8-s10r9 7/11/11
skins (F-850 and F-851 forward belly skins, or F-872 wing root fairing) with “U” type (NAS395) speed nuts.
RV-8 MAIN WHEEL FAIRINGS
RV-8 main wheel fairing installation is shown on DWG 45.
The VA-157 wheel fairing consists of two pieces, the VA-157A forward half and the VA-157B aft half. They should
mate as accurately as possible. Because of the variations possible in fiberglass moldings, the first step is to make
the halves fit. Use coarse sandpaper glued to a straight stick as a disposable file to remove any material that
prevents the halves from matching smoothly. Typical areas that might need some extra work are shown on Details
B and C; the inside radius of the flange on the rear half, the inside of the front half where glass cloth layers overlap,
etc. Take the time to custom fit the halves of your fairings as exactly as possible.
Drill and cleco the VA-157 fairing halves together. Begin at the tops of the fairings and work down the sides to help
minimize bulging and mismatch between the fairing halves. Space fasteners per Section C-C’. The fairings as
supplied are symmetrical (no right or left hand fairing) but the asymmetrical installation of the fasteners will establish
which fairing will be installed on the right side of the aircraft and which will be installed on the left.
Attach front and rear halves of wheel fairings to each other as shown in Sect. C-C’, DWG 45.
Mark a lengthwise centerline across the top of the assembled fairing.
Attach the U-808 Outboard Brackets to the VA-106 Axle Nuts using AN4-5A Bolts and AN960-416 Washers. There
is no right hand or left hand U-808, but there is a top and bottom. The longer leg of U-808 goes to the top. Using a
carpenter’s square or drafting triangle on the floor, rotate U-808 so the forward and aft edges are perpendicular to
the floor. Tighten the bolts.
Locate a small piece of 1 inch thick wood/metal/plastic to use as a spacer between the top of the tire and the inside
of the wheel fairing. This spacer will be placed on the top of the tire to establish the correct vertical position of the
fairing relative to the wheel/tire. (The 1” dimension assumes a 14” diameter tire is being used. Spacer thickness
may be varied to account for tire wear or inflation pressure.
Duct tape the spacer to the top of the tire.
Assuming the airplane is still jacked up off the floor and the longerons are level, the next step is installing the
fairings on the wheels.
The inboard forward edge of the aft fairing must be locally trimmed to clear the axle. The wheel fairing is positioned
correctly in the fore/aft direction when the forward edge of U-808 lines-up with the molded in “step” located
approximately 1” aft of the forward edge of the aft fairing (see Detail A).
Center the rear half of the fairing over the tire while using the spacer to hold it in the correct vertical position. Locate
and use some blocks of wood/metal/plastic to place under the aft end of the fairing to position the center of the aft
edge of the fairing 1 5/8” farther from the floor than the center of the axle (see Wheel Fairing Side View). Mark the
area of interference with the gear leg, remove the fairing, trim a small amount of the fairing away, and test fit the
fairing over the wheel until the fairing fits. Trim the minimum required to clear the gear leg as this will make the
construction of the intersection fairing easier.
When the weight of the airplane is off the gear, the wheels naturally relax in camber. The vertical axis of the fairing
is intended to be aligned with vertical axis
of the wheel and tire.
... not perpendicular to the ground. The tire tread
provides a good alignment guide. The centerline on the top of the fairing and center of the opening on the bottom
should align with the center of the tire.
When the aft fairing is located vertically (by the spacer on top of the tire), fore/aft (by alignment of the “step” with the
forward edge of U-808), approximately leveled (by the blocks under the aft end), and aligned with the tire, drill and
cleco it to the U-808 bracket using the pre-punched 0.125” diameter holes in U-808.
U-808 mates to the wheel fairing in a region where the fiberglass thickness is changing. This will cause
misalignment of the bracket, so a few plies of fiberglass cloth must be bonded to the inner surface of the aft fairing
to make the thickness constant in the two areas where U-808 touches the fairing. Use coarse sandpaper to
roughen the surface of the fairing --really roughen it, don’t be shy --before bonding patches of fiberglass cloth in
place with polyester resin.
Attach the forward half of the fairing to the aft half. Now carefully adjust the fairing position until it is aligned with the
aircraft centerline both in a horizontal plane (see View D-D’) AND in a vertical plane (see wheel fairing side view).
With the fairing held in its final position, drill and cleco the fairing to U-807 in four places (two front and two rear). It
is easier and safer to initially drill the holes #40 and then work up to the final #20 size.
