TM 1-6625-724-13&P
0071 00
0071 00-17
TASK 2 – TRACK AND BALANCE MAIN ROTOR ON GROUND
HELPFUL HINTS
1. Blade weights are turned off as a default and must be manually turned on (Edit Adjustables) when needed.
2. Pitch link adjustments will target reduction of track spread exclusively. They will effect lateral vibration, but that
effect will not drive the solution.
3. As long as ground lateral is at or below 0.6 ips, do not attempt to make weight adjustments together with pitch link
adjustments until track spread has been reduced to levels which require no more than ½ flat pitch link moves.
This will minimize the chances for compounding errors. If ground lateral is above 0.6 ips, make a weight
adjustment for the first move along with the pitch link adjustments to minimize the chance of damaging vibrations
on the second run-up, but don’t be surprised if some of that weight move needs to be removed on the next run.
4. Ground track and balance works efficiently when the AVA adjustments are used. For an aircraft in good
mechanical condition, two sets of ground adjustments, (pitch links only), (pitch links and weights only or weights
only), should be sufficient to drive track below 0.25 inch and lateral below 0.1 ips.
5. If weight adjustments are to be made, don’t ignore any of the pitch link adjustments. If pitch link adjustments are
ignored weight adjustment will no longer be correct. If certain pitch link adjustment is not desired, turn it off (Edit
Adjustables) and have the AVA recompute the weight and pitch link solution.
6. If the AVA calls for > 1017 grams on a given blade, go ahead and install nine –3 weights on that blade and take a
new measurement, before removing and/or swapping blades. If the aircraft is more sensitive than the script file
sensitivities, nine –3 weights may be enough or even too much.
7. If you have one or more pitch link adjustments or 3 flats or more combined with one or more 1/2 flat adjustments,
turn off the blades which are calling for the 1/2 flat adjustment and turn off the blade which had no adjustment and
recompute the AVA solution. In this way, the number of pitch link adjustments are minimized until track has
settled to the fine-tuning 1/2 flat level.
TROUBLESHOOTING
1. Track spread not reducing:
Check for droop stop sticking. Droop stop sticking can affect blade track.
2. If lateral vibration is not getting better or is increasing:
a. Check to ensure that the lateral accelerometer is mounted in the correct orientation (connector coming off to
pilot’s right). If mounted with the connector incorrectly coming off to the pilot’s left, the AVA hub weight
adjustments will drive the vibration in the wrong direction (i.e., away from polar chart center).
b. Check to ensure that the lateral accelerometer is wired to DAU port ACC1. If the vertical accelerometer is wired
to the lateral accelerometer channel (i.e., vertical accelerometer cable connected to ACC1), the lateral
measurement will be in error and the adjustment will correspondingly be in error.
