64-11 Static Balance (continued)
B. Spanwise Static Balance
CAUTION
Verify four washers installed under each blade’s outboard
fastener prior to tail rotor assembly installation or dynamic
balance.
1. Refer to Figure 64-3. Install standard hardware for initial spanwise static balance
check. Standard torque fasteners per § 20-32.
2. Install MT179-4 balance bar into tail rotor assembly. Install teeter hinge bolt, and
special torque nut to 350 in.-lb. Using a carpenters square, adjust balance bar
until approximately perpendicular to hub.
3. Place tail rotor assembly with balance bar on Anderson 20 or equivalent balancing
stand. Hold tail rotor assembly horizontally, then allow to fall. The falling blade
is the heavy blade; the rising blade is the light blade.
4. Spanwise balancing is achieved by varying nut-side washer size on light blade
outboard fastener. Four washers are required under outboard fastener nuts; place
largest washers closest to hub assembly. Select washers for balancing, standard
torque hardware per § 20-32, and repeat step 3.
5. Blades are balanced spanwise when blade does not fall when positioned horizontally
on balancing stand. Repeat step 4, adjusting outboard fastener washers until
blades are balanced.
6. Recheck chord and spanwise balance. Tail rotor assembly must be statically
balanced within 4 inch-grams. Remove MT179-4 balance bar.
APR 2019 Chapter 64 Tail Rotor Page 64.7
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