Dynon Avionics RV-4/8 Pitch Kit - Manual (Page 4)

DYNON AVIONICS
Servo Mounting Instructions – RV-4/8 Pitch Kit 3
101046-002 Rev F
location of the bell crank mounting holes. Remove the original brackets and clamp the new brackets
to the match-drill plate along the same edge and with the bell crank mounting holes aligned with the
reference mark. Flip the brackets and match drilling plate upside down, and drill new rivet holes in
the brackets. You may wish to trial assemble the pitch bracket assembly, as shown on page 8. This
can be done on the bench, and the rod end bearing position can be adjusted per the figure on page
9.
Attach the new brackets to the aircraft using the original rivet holes. The bell crank mounting hole
should be in exactly the same position it was with the original brackets. It is up to the installer to
supply the bracket mounting fasteners depending on what method was used to secure the original
equipment (not available from Dynon).
When installing this kit in an RV-8 manufactured after September 2006, it is up to the installer to
align and fasten the brackets to the fuselage. Start by removing the bell crank nut and bolt to align
the largest hole in the brackets with the holes in the upward-bent bell crank pivot bearing supports,
as shown on page 12. Dynon recommends temporarily using the supplied AN4H-15A bolt as a
locator while drilling through the brackets and fuselage. Fasten the brackets to the fuselage using the
installer’s preferred method and hardware (not available from Dynon).
Drill the bell crank according to the drawing on page 10. Use a supplied AN960-10 washer as a
support between the two halves of the bell when the linkage is fastened.
For a pre-September 2006 aircraft, install the supplied AN3H-4A bolt, MS35333-39 star washer, and
AN960-10 flat washer through the inside of the installed brackets and into the servo (in the hole
closest to the bell crank pivot bearing) referring to the drawing for servo orientation. Sandwich the
bell crank and the supplied 0.750" spacer between the mounted left bracket and the right bracket.
Pass the AN3H-13A bolt, MS35333-39 star washer, and AN960-10 flat washer through the right
bracket, spacer, left bracket, and tighten into the remaining hole of the servo.
For a post-September 2006 aircraft, install the supplied AN3H-5A bolt, MS35333-39 star washer,
and AN960-10 flat washer through the inside of the installed brackets and into the servo (in the hole
closest to the bell crank pivot bearing) referring to the drawing for servo orientation. Sandwich the
bell crank, bent bell crank pivot bearing supports, and the supplied 0.875" spacer between the
mounted left bracket and the right bracket. Pass the AN3H-15A bolt, MS35333-39 star washer, and
AN960-10 flat washer through the right bracket, spacer, left bracket, and tighten into the remaining
hole of the servo. Finally, replace the original AN4 bolt for the bell crank with the longer AN4H-
15A bolt supplied with this kit.
With the brackets, servo, and drilled aircraft bell crank installed, the linkage must be assembled and
mounted. Refer to the illustration and follow proper rod end installation techniques. Screw at least
half of the threads on each rod end into the push rod. To prevent the possibility of the servo arm
going over-center, the servo arm must not travel more than a total of +/-60º from neutral
throughout the control system's range of travel. The linkage should be installed as close to the
Dynon recommendation as possible, as changes will affect geometry. Dynon suggests installing the
linkage at the outer-most hole of the servo arm. Changing this location will affect servo torque
output, servo arm travel, control surface resolution, and the amount of force required to shear the
safety screw, and should only be changed if the installer has an understanding of these implications.
See the diagram on page 6 which illustrates the linear travel and available force for each mount point
on standard-arm servos.