KDE Direct Align Trex 550 Series User manual

Introducing the ultimate solution to prevent the front‐torque tube stripping and vibration‐related issues for the
full range of ALIGN TREX 550 and 600 series helicopters. The upgrade provides all the components needed to
produce a fully‐adjustable gear mesh between the autorotation gear and front‐torque tube gears, giving the
pilot the ability to adjust for full‐gear tooth strength and accommodate both the MOD 0.6 (4.5 ratio) and MOD
0.8 (3.85 ratio) gearing to suit their flying style. Dual Aluminum 6061‐T6 Case Supports are provided for
improved stiffness and a solid‐hold to the carbon frames for the Tail Boom Case, preventing any unwanted
shifting of the mechanics during flight for ultimate strength and smoothness of the tail gear train. In addition,
shims are provided for further adjustment of the bevel gears, further improving the strength and accuracy of
the tail gear train.

STEP 1: Disassemble the Tail Boom Case, Umbrella Gear Case, and Front‐Torque Tube Gear as shown in the
image below. Remove the Radial‐Ball Bearings from the Front‐Torque Tube Gear.
Optional Tool: To aid in installation, a 12 mm or 0.5” Drive Socket will be useful to install the 0.25 mm Shims
onto the Front‐Torque Tube Gear as described in the next page.
FRONT-TORQUE TUBE GEAR
UMBRELLA GEAR CASE
RADIAL-BALL BEARINGS
0.25 MM SHIMS
TAIL BOOM CASE
12 MM DRIVE SOCKET

STEP 2: Install one or two of the provided 12.0 x 15.0 x 0.25 mm Stainless Steel Shims between the Front‐
Torque Tube Gear and Radial‐Ball Bearing as shown during installation.
Use the 12 mm (or 0.5”) Drive Socket to push the 0.25 mm Shim onto the Front‐Torque Tube Gear without
bending the thin material, or be careful with installation using pliers or alternate methods.
0.25 MM SHIMS

STEP 3:InstalltheFront‐Torque Tube assembly into the Umbrella Gear Case (see original ALIGN Installation
Manual if needed). Once assembled, install the assembly into the Tail Boom Case and check gear mesh for
smooth operation.
Use one or two 0.25 mm Shims to provide a snug, but smooth gear mesh. Allow for minimal backlash to
provide significantly increased strength for hard tail maneuvers.
TEST GEAR MESH
DURING INSTALLATION

STEP 4: Finish assembling the Tail Boom Case on the bench and then using an Exacto‐knife or Dremel cut‐off
wheel, remove a small portion of the Tail Boom Case plastic tabs (towards the gears) as shown in the image
below. This will allow for forward adjustment of the Tail Boom Case as described in the following pages.
Approximately 1.0 mm – 2.0 mm of the plastic tabs should be removed, and repeat on the alternate side.

STEP 5: Using the included 5/32” (4 mm) Drill Bit, drill out the six mounting holes for the Tail Boom Case on
both the Right and Left Carbon Main Frames. The 550 series Carbon Main Frame is shown below, but same
procedure is used on all the TREX 550 and 600 (Electric and Nitro) frame sets for simple installation.
By increasing the hole sizes, adjustment of 0.5 mm (0.020”) is allowed in either direction to adjust gear mesh.

STEP 6: Install the Tail Boom Case assembly into the Carbon Main Frames, aligning the shortened plastic tabs
into the provided slots in the frames. Hole sizes can be further increased up to 3/16” (4.75 mm) to provide
additional adjustment capability for the gear mesh tolerance if required.
CRITICAL GEAR MESH
LOCATION

STEP 7: Install the provided Universal Tail Boom Case Supports (Right Frame and Left Frame sections provided)
using the included M3 x 0.5 x 10 mm Socket Head Cap Screws. Make sure to apply medium‐strength Loctite
(243 or equivalent) during the installation. Shift the Tail Boom Case location forward or aft to provide a snug,
butsmoothgearmeshattheAutorotationGearandFront‐Torque Tube Gear junction; then fully tighten all
hardware. Allow for minimal backlash to provide significantly increased strength for hard tail maneuvers.
CRITICAL GEAR
MESH LOCATION

Installation is complete and gear‐mesh has been optimized for a significant increase in gear‐tooth strength and
smooth‐running operation. With correct adjustment and minimal backlash, using the MOD 0.6 (4.5 tail ratio)
or MOD 0.8 (3.85 tail ratio) components is possible without fear of stripping the tail gear train; providing a
significant increase in tail authority and control for hard‐3D, competition‐level, and overall confident flying for
all pilots.