TASK 4 BALANCE TAIL ROTOR
AVA moves are changes to the adjustable tip weights
and, as such, are to be added to or subtracted from
whatever weights are currently in the blade tips.
The diagnostic solution given for each set of
measurements that have been previously performed.
The AVA does not maintain any history of adjustments.
It therefore makes no assumptions regarding what
adjustments were made during previous runs.
a. Examine the Limits screen. If measurements are within limits, press the UP cursor to display the measured
magnitude. If tail rotor balance is above 0.10 ips and it is desired to reduce it further, press QUIT to return to the
first limits screen, then continue with this procedure (do step b). If it is not desired to reduce balance to below
0.10 ips, press QUIT to terminate tail rotor balance procedures.
b. Press DO to calculate the adjustment.
The total weight move called for by the AVA for a given
blade should be equally split between the forward and
aft weight pockets, with 1/2 the weight adjustment made
to the forward pocket and 1/2 the weight adjustment
made to the aft pocket.
The addition of weight to a blade has the equivalent
effect on vibration as removal of the same amount of
weight from its opposite blade.
A weight change to an outboard blade is 50% more
effective than an equal weight change to an inboard
c. Recall the measured balance:
1. If the measurement is less than 0.7 ips, record and make the AVA-recommended adjustments. Do procedure
2. If the measurement is 0.7 ips or greater, Do procedure 5.1.
PROCEDURE 5.1 Tail Balance 0.70 ips
a. For balance greater than or equal to 0.7 ips, reduce the AVA-recommended adjustments by 1/2 for both inboard
and outboard blades. This will prevent adjustment overshooting for high imbalance.
b. Perform procedure 6.
PROCEDURE 6: VERIFY/REPEAT
Repeat tail measurement to determine whether or not the corrections had the desired affect. Repeat diagnostics/
corrections as necessary until vibration is within limits.