MD Helicopters CSP-900RMM-2, Техническое обслуживание и ремонт

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CSP − 900RMM − 2 MD Helicopters, Inc.
Rotorcraft Maintenance Manual
Page 1
Revision 3
62-00-00
MAIN ROTOR SYSTEM
DESCRIPTION AND OPERATION
1. Main Rotor System − General
(Ref. Figure 1)
The main rotor system is mounted on the static
support mast and driven by the main rotor drive
shaft. The main rotor system provides the lift,
and by control input, lateral, longitudinal, and
collective control. The main rotor system
consists of the main rotor blades, pitchcase
assemblies and main rotor hub assembly.
2. Main Rotor Blade Assembly
The main rotor blade assembly is attached to
the main rotor hub by the flexbeam and blade
retention bolts. Main rotor blades are
constructed of fiberglass using bonded
pre-cured spars and skins. Behind the spar
the blade is filled with a honeycomb core.
Each blade spans 154.88 inches with a chord
of 10.0 inches. The blades are twisted from
+10 degrees, at the root, to +4.5 degrees, 21.38
inches from the root. The twist is then linear
to -2.5 degrees at the tip. Twist helps to
equalize lift along the span of the main rotor
blade. A thinner airfoil section near the tip of
the blade is used to reduce the effects of air
compressibility at high speeds.
The main rotor blade installation includes:
A. Rotor Blade Retention Bolts
Rotor blade retention bolts are high torque bolts
with expandable bushings. They attach the
rotor blades to the pitchcase and flexbeam. With
the bolt inserted and torqued, the expansion
bushings create an interference fit installation
to lock the bolt in place. The rotor blade
retention bolt creates a positive alignment of the
pitchcase, flexbeam, and rotor blade.
B. Abrasion Strips
Two metal abrasion strips are bonded to the
leading edge of the rotor blade to provide
protection against erosion. Inboard abrasion
strips are titanium. Outboard abrasion strips
are nickel. Behind the lower edge of each
abrasion strip is a fiberglass pad that resists low
angle of incidence abrasion.
C. Trim Tabs
Trim tabs are located on the trailing edge of
each rotor blade. The trim tabs are bent up or
down to track the rotor blades.
D. Electrical Grounding
An embedded metallic mesh (Astrostrike ) in
the blade skin electrically connects the abrasion
strips with grounding lugs located near the root
of the blade. Bonding jumpers connect these
lugs to similar lugs in the pitchcase. This
electrical path reduces, or eliminates, damage
caused by lightning, and provides for static
discharge from the rotor blade.
3. Pitchcase Assembly
The pitchcase assembly is attached to the root
of the rotor blade by the retention bolts and
connected to the hub by the flexbeam. At­
tached to the hub end of the pitchcase is the
pitch change horn.
The pitchcase assembly includes:
A. Pitchcase
The pitchcase is torsionally rigid to transfer
control input to the rotor blade. Pitchcases are
a composite structure made of filament wound
graphite, with imbedded Astrostrike
for
electrical grounding.
B. Centering Bearing/Damper Assembly
The centering bearing and damper assembly
are installed at the hub end of the pitchcase.
The centering bearing fits onto a snubber bolt
in the lower hub half and provides a fixed
feathering axis for the rotor blade. The
centering bearing is captured between an
upper and lower elastomeric damper assembly
that help the flexbeam dampen out the
lead/lag motion of the rotor blade. Dampers
are retained to the pitchcase by upper and
lower bolted retainer caps.
C. Pitch Change Horn Assembly
The pitch change horn is a machined alumi­
num bracket attached to the hub end of the
pitchcase trailing edge. Pitch change links
transfer control input to the rotor blades
through the pitchcases.