Rotor System Flashcards
NATOPS Chap 2
Rotor System
What type of Rotor system do we have?
A fully articulated rotor system
NATOPS Chap 2
Rotor System
What are the four subsystems?
Main rotor blades, hub, flight controls, and bifilar vibration absorber.
NATOPS Chap 2
Rotor System
How are the rotor blades attached to the hub
They are attached to hinged spindles and are retained by elastomeric bearings contained in the hub
NATOPS Chap 2
Rotor System
What do the elastomeric bearings do?
They enable the blades to flap, lead, lag, and permit the blade to move about its axis for pitch changes
NATOPS Chap 2
Rotor System
How is the rotor controlled
Control is provided via hydraulic servos which move the control rods attached to the swashplate.
NATOPS Chap 2
Rotor System
How is the main rotor head supported
Via the shaft extension. The shaft extension is secured in place to the main shaft via the main rotor nut and the low pressure plate. The low pressure plate also provides an attachment for the swashplate assembly
NATOPS Chap 2
Rotor System
How does the swashplate affect control inputs to the blades?
The swashplate slides around the main rotor shaft and tilts in the direction of the flight controls on a Teflon- coated uniball. Four pitch rods extend from the swashplate and connect to pitch change horns on the spindle. The pitch control rods transmit all movement of the flight controls from the sqashplate to the main rotor blades. Each rod is ground-adjustable for blade tracking
NATOPS Chap 2
Rotor System
What do droop stops and flap restraints prevent?
They prevent extreme high or low blade flapping at low Nr
NATOPS Chap 2
Rotor System
At what Nr do flap restraints permit coning?
At 35% Nr or greater, centrifugal force pulls out the restraints to allow coning and flapping of the blades
NATOPS Chap 2
Rotor System
When do droop stops come out and in?
70% Nr and 50% Nr
NATOPS Chap 2
Rotor System
Main Rotor Blades have….
“A pressurized hollow spar, honecomb core, outer skin, abraasion strips, electrothermal deicing mats, and a removable swept-back blade tip fairing”
NATOPS Chap 2
Rotor System
What do the swept tips provide?
The 20* swept tips provide sound attenuation and rotor blade efficiency
NATOPS Chap 2
Rotor System
Tail rotor system is…
“A bearingless, crossbeam tail rotor blade system which provides antitorque action and direction control
NATOPS Chap 2
Rotor System
Where is the Tail Rotor and what does it provide?
On the right side of the Tail pylon, and it provides 2.5% lift in a hover due to the tail canted 20* upward
NATOPS Chap 2
Rotor System
What does the tail rotor indexing system provide
It prevents the Tail Rotor from windmilling in winds up to 60kts
NATOPS Chap 2
Rotor System
The Tail rotor head consists of..
Two plates. The inboard plat forms a hub, that is attached to the gearbox output shaft and retained by a shaft nut. The hub plates absorb axial thrust loads and bending moments and transmit torque to the tail rotor blades.
NATOPS Chap 2
Rotor System
Gust Lock Caution(s)
When locking the gust lock, the switch shall be held in the LKD/UNLK position for a minimum of 5 sec to enable the actuator mechanism to complete its cycle.
Should rotor brake hyd pressure bleed off in a folded condition, the gust lock will not prevent the rotor brake disk from turning
NATOPS Chap 2
Rotor System
What does AVCS do?
“Attenuates the magnitude and reduces the duration of the peak vibratory loads produced by the main rotor blade passage vibration frequency.”
NATOPS Chap 2
Rotor System
What is used to provide a reference signal to allow AVCS to track changes?
The Nr tachometer
NATOPS Chap 2
Rotor System
How many accelerometers/force generators are there?
The AVCS system uses 10 accelerometers and 5 force generators
NATOPS Chap 2
Rotor System
When should the AVICS BIT be performed
Shall only be initiated with rotors static to avoid damage to dynamic components
NATOPS Chap 2
Rotor System
Where are the main dampers installed, and what is their job?
They are installed between each of the main rotor spindle modules and the hub to restrain lead and lag motion of the main rotor blades during roation and to absorb rotor head starting loads. Each damper is supplied with nitrogen-pressurized hydraulic fluid form a reservoir mounted inside the main rotor shaft
NATOPS Chap 2
Rotor System
Where is the Tail Rotor Quadrant, and what triggers the TAIL QUADRANT caution?
The tail rotor quadrant is mounted on the tail gearbox and transmits tail rotor cable movements into the tail rotor servo. Two spring cylinders are connected to the quadrant. In the event a cable is broken, the quadrant will operate normally by controlling the remaining cable against spring tension. The related microswitch mounted on the quadrant will illuminate the TAIL QUADRANT caution
NATOPS Chap 2
Rotor System
What is the AVCS cycle?
It continuously analyzes aircraft vibrations and resets its vibration-nulling solution on a 300 seceond (5 min) cycle.
