AIRCRAFT SYSTEMS FLIGHT CONTROLS SA227‐ SERIES/FCOM/VTM 6.27.1 FLIGHT CONTROLS The flight controls are manually and electrically controlled from the pilot’s or copilot’s position by conventional means. The flight controls consist of ailerons with a trimmable balance tab on each aileron, the rudder with trim tab, a horizontal stabilizer which is electrically operated, elevators, and electrically controlled/hydraulically operated wing flaps. AILERONS The aileron control system is interconnected to dual control wheels for operation by either pilot. Cables are attached to a chain and sprocket segment at each control wheel. The cables are routed through the control column, then beneath the cabin center aisle floor, and connect to the aileron bow tie and bellcrank shaft which passes through the pressure vessel at a bearing seal. The shaft turns the main bellcrank which actuates push‐pull rods which are routed to the ailerons. The push‐pull rods are attached to a series of bellcranks mounted along the rear spar. Each aileron is attached to the wing at three brackets. An adjustable push‐pull rod, connected to a swing link at each outboard bellcrank, actuates the aileron. AILERON TRIM TABS The aileron trim tabs are controlled by a trim tab wheel on the control pedestal through a cable system which actuates the trim actuators mounted on the rear wing spars. The actuators move push‐pull rods through the ailerons to the tabs. The actuators also provide servo action during aileron movement.
6.27‐1 Aileron Control
Revision: Original Aug 1,2013
GO/FCOM/SA227‐SERIES/VTM
Figure
AIRCRAFT SYSTEMS FLIGHT CONTROLS SA227‐ SERIES/FCOM/VTM 6.27.2 RUDDER The rudder is controlled by the pilot’s or copilot’s rudder pedals which are interconnected by push‐pull rods. Bellcranks actuate the rudder cables from the cockpit to the rudder bow tie which is located forward of the aft pressure bulkhead. The rudder torque tube is attached to the bow tie and extends vertically through the pressure vessel. The torque tube is sealed internally by an aluminum plug. The fuselage cut out is sealed by an O‐ring assembly.
Figure 6.27‐2 Rudder Control
Figure 6.27‐3 Rudder Pedals
Revision: Original Aug 1,2013
GO/FCOM/SA227‐SERIES/VTM
AIRCRAFT SYSTEMS FLIGHT CONTROLS SA227‐ SERIES/FCOM/VTM 6.27.3 RUDDER TRIM TAB The rudder trim tab is actuated by a cable and chain operated actuator mounted in the vertical stabilizer. By turning the rudder trim control wheel located on the control pedestal, cable movement rotates a sprocket which actuates a push‐pull rod through the rudder to the tab, deflecting it in the desired direction.
Figure 6.27‐4 Rudder Trim
Revision: Original Aug 1,2013
GO/FCOM/SA227‐SERIES/VTM
AIRCRAFT SYSTEMS FLIGHT CONTROLS SA227‐ SERIES/FCOM/VTM 6.27.4 ELEVATOR The elevator is actuated by an arm mounted on the interconnecting torque tube between the two control columns. A push‐pull rod is connected between the arm and walking beam located centrally under the cockpit floor. Cables are routed around the walking beam and through a pulley arrangement to the aft fuselage section, then to a bellcrank installed in the vertical stabilizer. Two bellcrank push pull rods actuate the elevator. The elevator is aerodynamically balanced with set back hinges and statically balanced with lead weights.
Figure 6.27‐5 Elevator
Revision: Original Aug 1,2013
GO/FCOM/SA227‐SERIES/VTM
AIRCRAFT SYSTEMS FLIGHT CONTROLS SA227‐ SERIES/FCOM/VTM 6.27.5 HORIZONTAL STABILIZER The horizontal stabilizer is electrically positioned to provide pitch trim. Electric motors actuate interconnected jackscrews to provide a dual, fail‐safe trim system. Mechanical stops for the jackscrews are built into the actuator. Electrical limit switches for the motors are mounted inside the vertical stabilizer. A dual switch on each pilot wheel controls separate circuits to each motor. A trim selector/kill switch is mounted on the center pedestal. A pitch trim indicator gives the pilot visual reference of trim position. Trim‐in‐motion sonalerts are provided to indicate pitch trim actuation and alert the crew in the event of a pitch trim runaway.
Figure 6.27‐6 Horizontal Stabilizer
TRIM CONTROLS A master pitch trim switch is located on the pedestal. The center position of the switch is the OFF position. In the pilot (left) position, the pilot has trim control, in the copilot (right) position the copilot has control. This switch prevents the pilot and copilot from trimming the aircraft simultaneously. Pilot and Copilot Pitch Trim Control Switches The pilot and copilot pitch trim control switches, located on the control wheels, have double toggle actuators. Both halves of the switch must be operated simultaneously to provide trim operation. PILOT’S AUXILIARY PITCH TRIM A pilot’s auxiliary pitch trim switch is located on the pedestal. It is incorporated to facilitate single pilot operation should a malfunction occur in the pilot’s trim control circuitry. This allows the pilot to trim the horizontal stabilizer without having to reach across to the copilot’s trim switches on the copilot’s control wheel. POSITION INDICATING SYSTEM A pitch trim indicator is located on the instrument panel. An out‐of‐trim sonalert system is also provided. The sonalert is inoperative until the throttles are advanced for takeoff. If during takeoff roll an
Revision: Original Aug 1,2013
GO/FCOM/SA227‐SERIES/VTM
AIRCRAFT SYSTEMS FLIGHT CONTROLS SA227‐ SERIES/FCOM/VTM 6.27.6 out‐of‐trim condition exists, the out‐of‐trim sonalert will sound a warning. When the aircraft is airborne the sonalert is disabled.
Figure 6.27‐7 Pitch Trim and Control
Revision: Original Aug 1,2013
GO/FCOM/SA227‐SERIES/VTM
AIRCRAFT SYSTEMS FLIGHT CONTROLS SA227‐ SERIES/FCOM/VTM 6.27.7 WING FLAPS The wing flaps, controlled by a flap selector located on the right side of the control pedestal, are electrically actuated and hydraulically operated. A flap position indicator is located on the instrument panel. The flapsmay be lowered or raised in increments from 0 to 36 degrees. The flaps are interconnected for positive, symmetrical operation should hydraulic actuation be lost on one side. There are no emergency provisions to extend or retract the flaps in the event of complete electrical or hydraulic system failure.
Figure 6.27‐8 Flap Control and Indicator
Revision: Original Aug 1,2013
GO/FCOM/SA227‐SERIES/VTM
AIRCRAFT SYSTEMS FLIGHT CONTROLS SA227‐ SERIES/FCOM/VTM 6.27.8 GUST LOCK SYSTEM An internal, cable operated gust lock system is provided to lock the flight controls in the neutral position. The gust lock control lever is located forward of the power levers on the control pedestal. When the gust lock is engaged, the power levers are locked in the retarded position. This prevents aplication of power for takeoff. The gust lock control lever actuates a cable which is routed to lock pins at the aileron bow tie and the rudder bow tie. Cable movement actuates these spring‐loaded pins into lock pin holes when the flight controls are in neutral and holds the controls in the neutral or streamlined position until the gust lock is released. The lock pins are mounted in spring‐loaded housings to prevent engagement of the pins in the event of gust lock cable failure.
Figure 6.27‐9 Gust Lock
Revision: Original Aug 1,2013
GO/FCOM/SA227‐SERIES/VTM
AIRCRAFT SYSTEMS FLIGHT CONTROLS SA227‐ SERIES/FCOM/VTM 6.27.9 ELEVATOR GUST LOCK A gust lock belt is used to secure the control column in its nose up position. An alternate rudder gust lock, may be manufactured locally and installed.
Figure 6.27‐10 Elevator Gust Lock
Figure 6.27‐11 SAS Indicator
Revision: Original Aug 1,2013
GO/FCOM/SA227‐SERIES/VTM
AIRCRAFT SYSTEMS FLIGHT CONTROLS SA227‐ SERIES/FCOM/VTM 6.27.10 STALL AVOIDANCE SYSTEM A stall avoidance system (SAS) is incorporated in the aircraft to warn the pilot of an impending stall aurally by use of a horn, and visually, by instrument indication. The system also provides for actual stall avoidance by means of a stick pusher which applies a forward force of approximately 65 pounds to the elevator control. The SAS system is armed at liftoff and disarmed at approximately 145 knots. The aural warning horn sounds at about seven knots above stall speed and the stick pusher is automatically engaged approximately one knot before the actual stall. The system can be manually overridden by the pilot.
Figure 6.27‐12 Stall Avoidance
Revision: Original Aug 1,2013
GO/FCOM/SA227‐SERIES/VTM