Flight Controls Flashcards
FLIGHT CONTROL SYSTEM
The aircraft employs a hydromechanical flight control system which is mechanically activated using conventional cyclic, collective, and directional (pedals) controls, through a series of push pull tubes and bellcranks and assisted by four hydraulic servoac-tuators.
The four hydraulic servoactuators control:
• Lateral (cyclic) left
• Rotor pitch (collective) Middle
• Longitudinal (cyclic) Right
• Directional/Yaw (pedals)
Stabilator control system
The stabilator control system is used to optimize the pitch attitude of the airframe at various airspeeds. At low airspeeds, a selectable Nap-of-the-Earth/Approach (NOE/A) mode increases over-the-nose visibility for the aircrew
Linear Variable Differential Transducers (LVDTs)
are incorporated into each of the flight control axes to measure the positions of the controls and provide this data to the FMC.
Force trim system
The force trim system provides an artificial force gradient feel to reduce crewmember fatigue by utilizing a feel spring and a magnetic brake assembly.
Flight Management Computer (FMC)
a. Commands the flight control actuators
b. Provides software logic and interface for Attitude Hold, Altitude Hold, Automatic Stabilator Control, and SCAS
SAS (Stability Augmentation System)
Manipulates flight controls based on outside force deviations
Rate Damping - yaw <40 cruise all airspeeds
Turn Coordination - keep the aircraft in trim above 40 KTAS acc.
External Force Damping
SAS limits - Collective, Lateral, Directional = 10%|Longitudinal = 20%
SAS Saturation - due to SAS limitations, SAS may run out of authority or saturate requiring force trim release to reposition (about 3 seconds)
CAS
Increase of response to the flight control movement providing a uniform aircraft response for a given control input at all airspeeds
Command Augmentation System (CAS)
CAS is defined as an increase of response to the flight control movement. The CAS provides a uniform aircraft response for a given control input at all airspeeds.
Translational Rate Command (TRC).
Allows crew to reposition while still operating in position hold without the aircraft moving back to original position
Swashplate
The swashplate assembly receives control inputs from the two lateral links and the torque link and transmits the control inputs to the main rotor.
Scissors assembly
The two scissors assemblies transmit rotational power to the rotating swashplate from the main rotor head.
Torque Link
Torque link: transmits longitudinal motion to stationary swashplate and provides fixed mounting point for the stationary swashplate
Collective bellcrank
Collective bellcrank: receives input from the collective servo actuator and transmits vertical motion to the stationary swashplate.
Lateral Bellcrank
Lateral bellcrank: mounted on the collective bellcrank, receives input from the lateral servoactuator and transmits lateral motion to the stationary swashplate.
Longitudinal Bellcrank
Longitudinal bellcrank: mounted on the collective bellcrank receives input from the longitudinal servoactuator and transmits longitudinal motion the stationary swashplate.
