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TM 1-6625-724-13&P
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Main Rotor Track and Balance Guidelines:
a. NEVER ignore an AVA adjustment. Instead, turn the adjustment off and re-calculate the corrections.
b. For a “new” rotor that has not been previously tracked and balanced, perform blade static phasing, remove all hub
weights, and zero all tabs.
c. Perform GROUND flight plan. Weights default to OFF, pitch links default to ON. Examine default corrections.
1. If the maximum pitch link move is 1 flat or more, make the indicated pitch link move(s).
2. If the maximum pitch link move is 1/2 flat and track spread is greater than 0.25 inch, View Predictions and
look at the predicted lateral. If predicted lateral is less than 0.1 ips, make the pitch link moves only. If
predicted lateral is 0.1 ips or more, turn blades 1 and 2 weights ON, and make the computed weight/pitch link
adjustments.
3. If track spread is 0.25 inch or less but lateral vibration is 0.1 ips or more, Edit Adjustables to turn OFF all pitch
links and turn ON blades 1 and 2 weights. Perform the weight-only correction.
4. Repeat GROUND flight plan until track spread is within 0.25 inch and lateral vibration is below 0.1 ips.
d. Perform FLIGHT flight plan. Obtain measurements up to the highest forward speed that can be safely achieved
(pilot’s discretion). Minimizing vibration is the primary goal of the moves given. Track is secondary.
1. Default adjustables are pitch links and tabs (weights default to OFF) and the default solution will normally be
comprised of both adjustment types.
2. If any 6-10 or 8-10 tab adjustment is 2 or more, turn off the excessive 6-10 or 8-10 tab and turn on the next
larger tab region on that blade (4-10 or 6-10). Recompute the tab adjustments. Make the smaller bend to the
larger region.
3. If max measured forward flight vertical vibration is 0.6 ips or more, View Corrections & Predictions.
(a.) If measured hover and ground lateral are both within limits, turn off all 4 pitch links and examine the tab
only solution and predictions. If the tab only solution is as good or nearly as good as the pitch link/tab
solution, make the tab only solution.
(b.) If measured hover or ground lateral is above limits, but predicted hover and ground lateral are both within
limits, perform the default pitch link/tab corrections.
(c.) If predicted hover or ground lateral is above limits, turn blades 1 and 2 weights on, recompute corrections,
and make the recommended moves.
4. If max measured forward flight vertical vibration is below 0.6 ips, View Corrections and Predictions.
(a.) If measured hover and ground lateral are within limits, turn off all pitch links, recompute the tab only
corrections, and View Predictions. Compare the predicted vibration levels with those of the pitch link/tab
solution. If the tab only solution is as good as or nearly as good as the pitch link/tab solution, use the tab
only solution. If the solution with pitch links is significantly more effective than the tab only solution, and
the pitch link moves are 1 flat or less, use the pitch link/tab solution. If the pitch link moves are more than
1 flat, make the tab-only moves.
(b.) If no tabs have been turned on by default, turn ON tabs 8-10 for all 4 blades and turn all pitch links OFF.
Examine the predictions. Then turn all 4 pitch links back on with all 4 8-10 tabs and examine the
predictions. Compare the 3 sets of predictions (pitch links only, pitch links and tabs, and tabs only).
Throw out any pitch link solution with moves larger than 1 flat. If the tab only solution is as good or nearly
as good as the solutions with pitch links, make the tab only adjustments. If either of the pitch link
solutions looks significantly better than the tab only solution, make the more reasonable of the pitch link
only or pitch link/tab adjustments.
(c.) If measured hover or ground lateral is above limits, examine the corrections and predictions for the
default solution. Turn blades 1 and 2 weights on and examine the corrections and predictions. Next, turn
all 4 pitch links off and examine the predictions. If the weight/tab solution predicts to bring the laterals in
limits and is nearly as good as or is as good as the other two solutions with pitch links, make the
weight/tab solution. The weight/pitch link/tab solution should only be made if it is significantly better than
the other two solutions.
END OF WORK PACKAGE
