TB 1-1520-237-20-171
g.
Coat the shank, threads, and area under head of one replacement S6110-21085-004 main rotor shaft nut bolt
with primer, item 314, appendix D.
h.
Install replacement bolt in main rotor shaft nut while primer is still wet. Tighten bolt until a slight resistance is
felt as bolt contacts thrust washer. Torque bolt to 713-787 inch pounds.
i.
Repeat steps f, g, and h until all suspect bolts are removed.
j.
Wipe off any primer that has seeped from under bolt heads using machinery towel, item 253, appendix D.
k.
Touch up paint on bolts as necessary (paragraph 2-5 of TM 55-1500-345-23).
NOTE
Lockring must be installed over bolts on main rotor shaft nut before corrosion preventative compound
dries.
l.
Apply corrosion preventative compound, item 136, appendix D, to main rotor shaft nut and to area inside
shaft extension.
m.
Coat the shank, threads and area under head of lockring bolts with primer, item 314, appendix D.
CAUTION
Damage to lockring will result if it is not seated properly prior to torquing bolts. Lockring must sit flat
on main rotor shaft nut. Turn bushings in lockring to allow locking to seat over bolts.
n.
Install lockring over bolts on main rotor shaft nut (TM 1-1520-237-23, figure 5-5, sheet 2, detail B). Make
sure two shorter spacers of lockring are resting on lock. Install bolts and washers while primer is still wet. Torque bolts to
176-194 inch pounds. Wipe off any primer that has seeped out from under bolt heads using machinery towel, item 253,
appendix D.
o.
If de-ice kit was installed, install main rotor blade de-ice tube and distributor and slipring assembly (TM 1-
1520-237-23, paragraph 12.7) and go to step t.
p.
Coat the shaft, threads and area under head of the bifilar bolts with primer, item 314, appendix D.
q.
Place bifilar cover over bifilar and install bolts and washers while primer is still wet. Torque bolts to 38-42
inch pounds.
r.
Wipe off any primer that has seeped from under bolt heads using machinery towel, item 253, appendix D.
s.
Seal edge of bifilar cover and area around bifilar bolt heads with sealing compound, item 371, appendix D.
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