TASK 3 - TRACK AND BALANCE MAIN ROTOR IN FLIGHT
PROCEDURE 4: VERIFY / REPEAT
a. Make the recorded AVA-recommended adjustments. For AH-64A, perform pitch link adjustments according to the
instructions in task 2 procedure 4 and perform trim tab adjustments according to procedure 5 below. For the AH-
64D, perform pitch link and trim tab adjustments as per the Longbow IETM, TM 1-1520-LONGBOW/APACHE.
b. Perform limited test flight, including autorotational RPM check per TM 1-1520-238-MTF. Repeat diagnostics/
corrections as necessary until all vibrations are within limits.
If trim tab pockets are not marked or to verify tab pocket
marking, for AH-64A refer to TM 1-1520-238-23 and AH-
64D to IETM TM 1-1520-LONGBOW/APACHE.
PROCEDURE 5: TRIM TAB ADJUSTMENT
a. The tab bend corrections called out on the diagnostics display will refer to the start point of a continuous bend.
Example: If the AVA recommends 1 degree up at pocket 4-10, the bend should start at pocket 4 and continue
through pocket 10.
Place tab adjustment tool in the center of the tab
bend pocket that is to be bent. See figure 10.
Tab tracking locations (0 through 10) are 10 inches
in length, starting six inches inboard of swept tip.
Do not bend inboard of pocket 10. See figure 11.
Do not make bends in opposite directions in
adjacent pockets. It is preferable to remove an
upward bend (reset to zero degrees) if the adjacent
pocket requires a downward bend.
Any noticeable deformity (kinks or sharp edges
caused by the tab bending tool) is cause for
rejection of the blade.
It is preferable to make two 1-degree bends in
adjacent stations rather than one 2-degree bend in
b. Perform tab adjustments on blades and pockets called out in the AVA diagnostics.
c. Remove tab adjustment tools and perform limited test flight as prescribed by procedure 4