AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)
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AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS) Presented by
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AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS). Presented by. PURPOSE: To develop the Student Instructor Pilot’s understanding of the Automatic Flight Control System NEED: You will be instructing this subject in the near future. TOPICS OF DISCUSSION. Auto Flight Control System - PowerPoint PPT Presentation
Transcript of AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)
AUTOMATIC FLIGHT CONTROL SYSTEM
(AFCS)
Presented by
• PURPOSE: To develop the Student Instructor Pilot’s understanding of the Automatic Flight Control System
• NEED: You will be instructing this subject in the near future
TOPICS OF DISCUSSION
• Auto Flight Control System • What is Stability?• Stability Augmentation System• TRIM• Flight Path Stabilization• Malfunction Analysis
WHAT IS AFCS?
• AFCS enhances the stability and handling qualities of the UH60 helicopter. It is comprised of four subsystems:¤ Stability Augmentation System (SAS)¤ Trim Systems¤ Flight Path Stabilization (FPS)¤ Stabilator (previously discussed)
WHAT IS STABILITY?
• Stability, in physics and engineering, the property of a body that causes it to return to its original position or motion as a result of the action of the so-called restoring forces, or torques, once the body has been disturbed from a condition of equilibrium or steady motion.
STABILITY AUGMENTATION SYSTEM (SAS)
• Purpose: Provide dynamic stability through short term rate dampening in the pitch, roll, and yaw axis.
• SAS systems: SAS 1 & SAS 2• Control Authority: Each SAS has 5%
control authority, for a total of 10%
SAS 1• Components:
¤ SAS1 amplifier (analog) is located in the avionics compartment
¤ Three SAS actuators • Input Signals:
¤ Pitch - rate gyro in the #1 stabilator amplifier¤ Roll - pilot’s (number 2) vertical gyro¤ Yaw - yaw rate gyro in the SAS1 amplifier¤ additional signals - #1 filtered lateral
accelerometer, airspeed transducer
#1 pitch rate gyro#2 vertical gyro
#1 lateral accla/s transducer
Yaw gyro
SAS 2• Components:
¤ SAS2 is the SAS/FPS computer (digital)¤ Three SAS actuators
• Input Signals:¤ Pitch - rate gyro in the #2 stabilator amplifier¤ Roll - roll rate gyro in the avionics compartment¤ Yaw - yaw rate gyro in the avionics
compartment
SAS 2
• Additional Signals ¤ #1 & #2 filtered lateral accelerometer ¤ rate gyro in the #1 Stabilator amplifier¤ air data transducer
Roll rate gyro
#2 pitch rate gyro
Yaw rate gyro#1 & #2 lateral acclAir data transducer
TRIM SYSTEM
• Purpose: Provide a gradient force, maintains position of the cyclic and tail rotor controls
• Components:¤ two electromechanical actuators, and one
electrohydromechanical actuator¤ TRIM REL switch on the cyclic, and pedal micro
switches on the directional control pedals¤ monitored by the SAS/FPS computer
TRIM SYSTEM
• Slip Clutches¤ both the roll and yaw trim actuators
incorporate slip clutches to allow the pilots to make control inputs should either actuator jam
¤ 13 pounds maximum in the roll¤ 80 pounds maximum in the yaw
Airspeed transducer
#1 collective position sensors
FLIGHT PATH STABILIZATION
• Purpose: Enhances static stability through long term rate dampening in the pitch, roll, and yaw axis.
• Components: SAS/FPS computer, and three trim actuators
• Control Authority: When coupled with trim, 100% control authority
FLIGHT PATH STABILIZATION
• The following systems must be on and operational for FPS to function 100%¤ SAS 1 and/or SAS 2¤ Boost¤ Trim¤ Stabilator in AUTO mode enhances FPS
operation, but is not required
FLIGHT PATH STABILIZATION
FPS provides the following functions:
60 KIASBELOW ABOVE
Attitude Hold
Attitude Hold
Attitude Hold/Airspeed Hold
Attitude Hold
Heading Hold
Pitch Axis
Roll Axis
Yaw Axis Heading Hold orTurn Coordination
Airspeed transducer
#1 collective position sensor
#1 pitch rate gyro#1 vertical gyro
#1 vertical gyro
ASN 43#1 lateral acclAirspeed transducer#1 collective position sensor
MALFUNCTION ANALYSIS
AUTO FLIGHT CONTROL
SAS 1 SAS 2 TRIM FPS
ON
BOOST FAILURE ADVISORY
ONRESET
POWER ON RESET
RESET
ON ON ON ON
9.29.1 SAS Failure With No Failure/Advisory Indication.
SAS 1 switch - Off.
If condition persists:
SAS 1 switch - On.
SAS 2 switch - Off.If malfunction still persists:
SAS 1 and FPS switchs - Off.
AUTO FLIGHT CONTROL
SAS 1 SAS 2 TRIM FPS
ON
BOOST FAILURE ADVISORY
ONRESET
POWER ON RESET
RESET
ON ON ON ON
SAS2
Power On Reset switches - Simultaneously press and then release.
9.29.2 SAS2 Failure Advisory Light On.
AUTO FLIGHT CONTROL
SAS 1 SAS 2 TRIM FPS
ON
BOOST FAILURE ADVISORY
ONRESET
POWER ON RESET
RESET
ON ON ON ON
SAS OFF
9.29.3 SAS OFF Caution Light On.
FPS switch - Off.
AUTO FLIGHT CONTROL
SAS 1 SAS 2 TRIM FPS
ON
BOOST FAILURE ADVISORY
ONRESET
POWER ON RESET
RESET
ON ON ON ON
SAS OFF
AUTO FLIGHT CONTROL
SAS 1 SAS 2 TRIM FPS
ON
BOOST FAILURE ADVISORY
ONRESET
POWER ON RESET
RESET
ON ON ON ON
A /S
FLT PATH STAB
9.29.4 FLT PATH STAB Caution Light On.
POWER ON RESET switches - Simultaneously press and then release.
WARNING
If the airspeed fault advisory light is illuminated, continued flight above 70 KIAS with the stabilator in the AUTO MODE is unsafe since a loss of the airspeed signal from the remaining airspeed sensor would result in the stabilator slewing full down.
9.29.5 Pitch, Roll or Yaw/Trim Hardover.
POWER ON RESET switches - Simultaneously press and then release.
If failure returns, control affected axis manually.
9.29.6 Trim Actuator Jammed.
LAND AS SOON AS PRACTICABLE.
QUESTIONS
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