62-20 Main Rotor Hub (continued)
B. Installation (continued)
6. Using wrenches with at least 600 ft-lb torque capacity, tighten nut until drilled hole in
nut and bolt align. Reinstall MT122-6 tool and measure bolt stretch; the stretch must be
between 0.020-0.022 inch (0.021-0.022 inch for new, undrilled bolt). Remove tool.
NOTE
If drilled holes in nut and bolt do not align, both nut and bolt
must be replaced. Stretch new bolts per Section 20-33; drill
new nuts and bolts per Section 62-33.
WARNING
The main rotor blade and hub attach bolts must be stretched
from 0.020 - 0.022 inch (0.021 - 0.022 inch for new, undrilled
bolt) to obtain proper clamping force. Under-stretching or over-
stretching can cause catastrophic failure of the bolts.
7. Verify correct teeter hinge friction per Section 62-32; adjust as required and perform
step 6.
8. If required, drill cotter pin hole per Section 62-33. Coat a new cotter pin with epoxy
primer and install wet.
62-21 Bearing Replacement
Refer to R66 Illustrated Parts Catalog (IPC) Figure 62-3.
1. Remove main rotor hub per Section 62-20.
2. If main rotor hub is to be reinstalled with same blades, measure and record shim
thicknesses and locations in hub.
3. Refer to Figures 62-2 and 62-3. Measure and record hub width across widest point of
teeter and coning hinge bearing faces (total of three measurements).
CAUTION
To prevent hub damage ensure all tool and bearing surfaces are
smooth.
4. Refer to Figure 62-5. Press old bearing(s) out of hub using a socket having an outer
diameter of 1.535-1.555 inches and an 8 inch extension.
CAUTION
Ensure hub is flat on press table and socket is centered on
bearing to prevent hub damage.
5. Inspect hub bearing bore. Verify no scoring or scratches. Polish out fretting and
corrosion to a maximum depth of 0.001 inch (0.005 inch on radius at edge of bore) using
320-grit or finer wet-or-dry sandpaper and 0.25 inch minimum blend radius. Replace
hub if fretting or corrosion cannot be polished out within limits.
25 OCT 2010 R66 Maintenance Manual Chapter 62 Main Rotor Page 62.9
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