Rotor Flashcards
Rotor Type/Subsystems
Fully articulated
Main rotor blades, hub, flight controls, and bifilar vibration absorbers
Assembly
Four main rotors attached to hinged spindles, retained by elastomeric bearings (enable flap, lead/lag, and permit blade to move about its axis for pitch change). Connected to spindle assembly outboard of blade-fold hinge by means of bolted flange
Bifilar vibration absorber mounted on top of hub
Main rotor dampers installed between each of main rotor spindle modules and hub to restrain lead and lag motions during rotation and absorb rotor head starting loads (supplied with nitrogen pressurized hydraulic fluid from reservoir in hub)
Spindles rest on droop stops when not turning
Upper anti-flap restraints limit flapping motion at low rpm
Main Rotor Head
Transmits flight control to main rotor blades
Supported by main rotor shaft extension
Main rotor shaft extension secured by low pressure plate and main shaft nut (low pressure plate also provides attachment for swashplate assembly)
Swashplate Assembly
Stationary and rotating discs separated by ball bearing
Transmits flight control inputs via pitch control rods then to pitch change horn
Slides around main rotor shaft and tilts in direction of flight controls on teflon coated uniball
Droop Stops/Flap Restraints
Prevent extremely high/low blade flapping at low Nr
Anti-flap out about 35% Nr allowing flapping/coning
Droops out about 70% Nr allowing full flapping action
Droops seat about 50% Nr
Main Rotor Blade
Nitrogen pressurized hollow spar (BIM black if leaking), honeycomb core, abrasion strips, electrothermal deicing mats and removable 20* swept back blade tip fairing (efficiency and sound attenuation)
Tail Rotor
Tractor type, 20* canted upward
Provides 2.5% total lift in hover
Bearingless crossbeam provides antitorque and directional control
Flap and pitch change motions result from deflection of the flexible spar
Tail Rotor Quadrant
Mounted on tail gearbox, transmits tail rotor cable movements into tail rotor servo
2 spring cylinders connected to quadrant:
With loss of both, spring-tension feature provides positive pitch equivalent to antitorque requirements for midposition collective setting (left pedal)
One fail, maintain full control of remaining cable against tension of other spring
Tail Rotor Index
Positions tail rotor blades during pylon fold operations and prevents windmilling in up to 60 knot winds
Tail Rotor Head
Two plates; inboard forms hub attached to gearbox output shaft and retained by shaft nut
Hub plates absorb axial thrust loads and bending moments and transmit torque to blades
Blade spars clamped between the two plates
Pitch change crossbeam attached to pitch-change shaft from center of gearbox
Tail Rotor Blades
Built around two composite, interchangeable spars
Twisting spar enables blade pitch changes
Have abrasion strips with electrothermal blankets
Rotor Brake System
Pressure builds in lines holding blades in place when brake applied
Activates ROTOR BRAKE caution and sets ground idle quadrant lock
Spring provides backpressure in case of leak (maintains brake until released)
Gust Lock
Teeth on rotor brake disc used for gust lock to position rotor head during blade fold
Primary function to lock rotor brake in indexed position and to prevent rotor brake disc from turning if pressure bleeds off
Gust Lock Caution
Whenever locking or unlocking gust lock, switch shall be held in LKD or UNLK position for min 5 seconds. Failure to do so may result in partially engaged gust lock with no indications causing damage when engaged
