ROTOR SYSTEMS Flashcards
Main Rotor System type and subsystems
fully articulated main rotor system
main rotor blades, hub, flight controls, and the bifilar vibration absorber
The elastomeric bearings per blade enable:
- blades to flap, lead, and lag
- permit the blade to move about its axis for pitch changes
Main rotor dampers purpose:
restrain lead and lag motions of the main rotor blades during rotation and absorb rotor head starting loads
supplied with nitrogen-pressurized hydraulic fluid
from a reservoir mounted inside the main rotor shaft
The 1-gallon reservoir, located in the main rotor mast, is shared between all dampers and has indicators to monitor the fluid level and nitrogen pressure
Swashplate purpose:
It transmits flight control movement to the main rotor through four pitch control rods
The droop stops and flap restraints prevent:
extremely high or low blade flapping at low Nr
Antiflap restraints go out at:
When the main rotor is
at 35 percent Nr or greater, centrifugal force pulls the antiflapping restraints outward and holds them in position to permit flapping and coning of the blades
As rotor speed increases, the droop stops:
rotate from their static
position to a dynamic position, allowing full blade flapping action. Centrifugal force pulls the droop stops out at approximately 70 percent Nr and permits increased vertical movement of the blade.
On shutdown, droop stops:
will seat at approximately 50 percent Nr
Blade build and composition
pressurized hollow spar,
honeycomb core, outer skin, abrasion strips, electrothermal deicing mats, and a removable swept-back blade tip
fairing
Blade sweep angle and purpose
20° swept tips provide both sound attenuation and increased rotor blade efficiency
Blade de ice provided by what blade component?
electrothermal
blanket is bonded into the leading edge
Abrasion strips provide what?
extend the useful life of the blades
The spar of the main rotor blade is pressurized with?
nitrogen
If the blade is damaged and the structural integrity of the spar is impaired, nitrogen will escape and cause the Blade Inspection
Method (BIM®) pressure indicator to show a black, or unsafe, indication
Tail Rotor System:
bearingless, crossbeam tail rotor blade system
Tail rotor blade flap and pitch-change motions result from:
deflection of the flexible spar