TM 1-1520-240-102-8-1/(2-8-2 blank)SECTION VIII. ROTOR SYSTEM2-8-1. General.Lift is produced by a rotor system consisting of two fullyarticulated counter-rotating rotors. Each rotor has threefiberglass blades. The forward rotor is driven by the for-ward transmission through a rotor drive shaft. The aftrotor is driven by the aft transmission through a verticaldrive shaft.The rotor head consists of a hub connected to threepitch-varying shafts by three horizontal hinge pins.These pins permit blade flapping. Stops on the top andbottom of the hub limit the blade flapping motion. The aftrotor head is equipped with centrifugal droop stops whichprovide increased blade flapping angle for ground andflight operation.Covers may be installed on the centrifugal droop stopoperating mechanism. The covers prevent ice accu-mulation on the mechanism and ensure proper droopstop operation following flight in icing conditions. For in-formation on use of the droop stop covers, refer to Chap-ter 8, Section IV.Mounted coaxially over the pitch-varying shafts are pitch-varying housings to which the blades are attached byvertical hinge pins. These pins permit blade leading andlagging. Each pitch-varying shaft is connected to thepitch-varying housing by a laminated tie bar assembly.The high tensile strength and low torsional stiffness of thetie bar retains the blade against centrifugal force andallows blade pitch changes about the pitch axis.Blade pitch changes are accomplished by three pitch-varying links connected from the rotating ring of theswashplate to the pitch-varying housing on each rotorblade. Cyclic pitch changes are accomplished by tiltingthe swashplate. Collective pitch changes are accom-plished by vertical movement of the swashplate. Com-bined collective and cyclic pitch change result from com-bined control inputs by the pilot.A direct-action shock absorber is attached to the bladeand to the pitch-varying housing. When the inboard endof the shock absorber is disconnected, the blade can befolded in either direction about the vertical hinge pin.2-8-2. Rotor Blades.a.Each rotor blade consists of D-shaped fiberglassspar assembly and a Nomex fairing assembly bonded tothe spar. The blade chord is 32 inches.b.A titanium nose cap is bonded to the leading edgeof the spar. A nickle erosion cap is bonded to the bladealong the outer 54 inches of leading edge. This cap pro-tects the part of the blade most vulnerable to erosion.c.The fairing assembly is bonded to the trailingedge of the spar. These fairings are constructed of aNomex honeycomb core covered with fiberglass skin.Wire mesh screens are embedded in the fiberglass skinat the tip and the trim tab. the wire mesh screens providean electrical path to the rotor hub from the metal trim taband tip for lightning protection. Also, to provide lightningprotection, each blade has two lightning cables and twostraps. The cables and straps complete the path from thewire mesh to the rotor head.d.Balance and tracking weights are installed in thetip of spar and fairing assembly. The tracking weights areremovable and are used for blade track and balance.2-8-3. Rotor Tachometers.Two rotor tachometer (16, fig. 2-1-7 and fig. 2-1-9), onemounted on the pilot instrument panel, the othermounted on the copilot instrument, indicate percent ofrotor revolutions per minute (RRPM). A small needle onthe tachometer indicates percent RPM from 0 to 60. Thelarge needle indicates percent RPM from 60 to 130. TheRRPM sense signal is supplied by the AC generators.generator No. 1 supplies the copilot indicator and gener-ator No. 2 supplies the pilot indicator. Power to operatethe indicators is supplied by the DC essential bus throughthe ROTOR TACH circuit breaker on the No. 1 and No.2 PDP.
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
