Cessna Citation II Flight Controls Dr Kurt Barnhart

Cessna Citation II Flight Controls Dr. Kurt Barnhart AST 473

Flight Controls • Overview – Primary Flight Controls • Ailerons • Rudder • Elevator -Manually actuated by rudder pedals and control column -Can be immobilized by control locks on ground -Mechanical Trim in all three axis + elec. Elev. trim

Flight Controls • Secondary Flight Controls– Electric flaps – Hydraulic speedbrakes -Stall Warning- stall strip on leading edge of each wing- aerodynamic buffet -Yaw damping- autopilot

Flight Controls • General- control inputs are transmitted via cables and bellcranks • Rudder pedals are 3 position adjustable via a spring latch on rudder pedals-side • Fences on inboard edge of rt. Aileron and inboard edge of left aileron trim tab- air ailerons in returning to neutral

Flight Controls • Rudder, rt. Elevator and left aileron- mechanical • • trim tabs actuated from cockpit Pilot’s and co-pilot’s (optional) cnt’l wheel have a pitch trim switch Control locks- on primary flight controls and throttles- operated from cockpit: – – Neutralize controls & idle throttles Rotate handle (CW) 45 deg. & pull until handle returns to horizontal- to release- rotate CCW & push in until horizontal- DO NOT TOW WHEN LOCKED!

Flight Controls • Trim systems- standard mechanical- cockpit • • • actuated & indicated Rudder trim- only servo tab on aircraft- deflects at half rate of rudder- aids pilot movement Elec. Trim- outboard horn of ea. cnt’l wheelpilot’s inputs overrides co-pilots AP/TRIM DISC on cont’l wheel or pulling PITCH TRIM CB- controls runaway trim

Flight Controls • Secondary control – Fowler flaps- 0 – 40 deg. , mechanically interconnected- prevents flap asymmetry and allows operation by one elec. Actuator – Speedbrakes- slotted panels on top & bottom of ea. Wing fwd. of flaps: • Used for increased descent rates • Increased drag and lift destruction on lndg.

Flight Controls • Flaps- – Detented @ 15 deg. Position (T/O & lndg. ) – Handle movement actuates switch- energizes two motors- position mechanically indicated on cockpit – Motors interconnected mechanically & actuated mechanically- normally operate in unison but one motor provides sufficient for normal operation

Flight Controls • Flap Operation– Moving flap handle- activates 1 of 2 switches in center pedestal- supplies pwr. To motors – At selected position- position indicator mechanically repositions cnt’l sw. to remove pwr. From motors – Mechanical drag- holds flaps in position – Limit sw. - prevent overrun up or down – No D. C. - N Flaps- fail in position – Travel time- 6 sec. 0 -full down, 3 sec. back

Flight Controls • Speedbrakes- 2 positions- up & down – 2 hyd. Actuators – Solenoid valve – 4 speedbrake segments – SPD BRAKE EXTENDED annunciator – Pedestal control switch

Flight Controls • Speedbrake Operation: – Placing speedbrake sw. in EXTEND • Closes hyd. Bypass valve (HYD. PRESS ON lt. ) • Energizes speedbrake solenoid valve- press. To speedbrakesforces them out of mech. Downlocks • Safety valve- also closed • 2 position switch- spring loaded to retract- (can be held ext. above 85% N(2)- early models only) • At full travel press. Builds, bypass valve opens, annunciator goes out- solenoid valve neutralizes- trapping hyd. Press in actuators- holding extension

Flight Controls • Speedbrake Retraction– – – Place switch in retract Hyd. Sys. Pressurizes Safety valve opens (de-energizes) Solenoid valve directs press. For retraction Annunciator goes out- “Boards” retract into mechanical locks- system depressurizes – Locks- 2 pins on lower board panel- hydraulically forced into retaining clips.

Flight Controls • Most models- if throttles above 85% N(2)- solenoid valve and bypass valve position for retraction • Safety valve- if elec. Failure w/ boards outspring loads open- allows boards to blow down • If elec. Failure w/ boards retraction- no actuation possible

Flight Controls • Stall Warning- stall strip on leading edge of ea. Wing for aerodynamic buffet • Buffet- VS(1) +10 (clean) and VSO + 5 (dirty)

Flight Controls • Yaw Damping- function of autopilot – Consists of automatic application of rudder against transient motion in YAW – YD automatically engaged w/ autopilot – Not required for flight – Can be engaged w/o autopilot by pushing YD ENGAGE sw. on autopilot – Disengaged by pressing AP/TRIM DISC on cnt’l wheel

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