Beechcraft C-12C Operator And Technical Reference Manual

Contents

Beechcraft C-12C Operator And Technical Reference Manual Manual pdf 85 page image

TM 1-1510-218-102-69d. Rudder Trim Tab Control. The rudder trimtab control knob, placarded RUDDER TAB / LEFT /RIGHT, is on the control pedestal, and controlsadjustment of the rudder trim tab, Figures 2-7 and 2-9.The amount of rudder tab deflection, in degrees from aneutral setting, is indicated by a position arrow.2-49. WING FLAPS.The all-metal slot-type wing flaps are electricallyoperated and consist of two sections for each wing.These sections extend from the inboard end of eachaileron to the junction of the wing and fuselage.During extension, or retraction, the flaps are operatedas a single unit, each section being actuated by aseparate jackscrew actuator. The actuators are driventhrough flexible shafts by a single, reversible electricmotor. Wing flap movement, either up or down, isindicated in percent of travel by a flap positionindicator on the subpanel. Full flap extension andretraction time is approximately 11 seconds. The flapcontrol switch is located on the control pedestal. Noemergency wing flap actuation system is provided.With flaps extended beyond APPROACH positionregardless of power setting, the landing gear warninghorn will sound, and the landing gear switch handlelights will illuminate unless the landing gear is downand locked. The circuit is protected by a 20-amperecircuit breaker, placarded FLAP MOTOR, located onthe overhead circuit breaker panel, Figure 2-16.a. Wing Flap Control Switch. Flap operation iscontrolled by a three-position switch with a flap-shapedhandle on the control pedestal, Figure 2-7 and 2-9.The handle of this switch is placarded FLAP andswitch positions are placarded FLAP UP /APPROACH / DOWN. The amount of downwardextension of the flaps is established by position of theflap switch, and is as follows: UP – 0%, APPROACH –40%, and DOWN – 100%. Limit switches, mounted onthe right inboard flap, control flap travel. The flapcontrol switch, limit switch, and relay circuits areprotected by a 5-ampere circuit breaker, placardedFLAP CONTR, located on the overhead circuit breakerpanel, Figure 2-16. Flap positions between UP andAPPROACH cannot be selected. For intermediateflap positions between APPROACH and DOWN, theAPPROACH position acts as an off position. To returnthe flaps to any position between full DOWN andAPPROACH place the flap switch to UP and whendesired flap position is obtained, return the switch toAPPROACH detent. In the event that any twoadjacent flap sections extend 3° to 5° out of phasewith the other, a safety mechanism is provided todiscontinue power to the flap motor.b. Wing Flap Position Indicator. Flap positionin percent of travel from "0" (UP) to 100% (DOWN), isshown on an indicator, placarded FLAPS, below theinstrument panel, Figure 2-17. The APPROACH andfull DOWN or extended flap position is 14° and 34°,respectively. The flap position indicator is protected bya 5-ampere circuit breaker, placarded FLAP CONTR,located on the overhead circuit breaker panel.Section VI. PROPELLERS2-50. DESCRIPTION.A three-bladed aluminum propeller is installed oneach engine. The propeller is of the full feathering,constant speed, counter-weighted, reversing type,controlled by engine oil pressure through single action,engine driven propeller governors. The propeller isflange mounted to the engine shaft. Centrifugalcounterweights, assisted by a feathering spring, movethe blades toward the low RPM (high pitch) positionand into the feathered position. Governor boostedengine oil pressure moves the propeller to the highRPM (low pitch) hydraulic stop and reverse position.The propellers have no low RPM (high pitch) stops;this allows the blades to feather after engineshutdown. Low pitch propeller position is determinedby the low pitch stop which is a mechanically actuated,hydraulic stop. Beta and reverse blade angles arecontrolled by the power levers in the beta and reverserange.2-51. FEATHERING PROVISIONS.The aircraft are equipped with both manual andautomatic propeller feathering. Manual feathering isaccomplished by pulling the corresponding propellerlever aft past a friction detent. To unfeather, thepropeller lever is pushed forward into the governingrange. An automatic feathering system will sense lossof torque oil pressure and will feather an unpoweredpropeller. Feathering springs will feather the propellerwhen it is not turning.a. Automatic Feathering. The automaticfeathering system provides a means of immediatelydumping oil from the propeller servo to enable thefeathering spring and counterweights to startfeathering action of the blades in the event of anengine failure. Although the system is armed by aswitch on the overhead control panel, placardedAUTOFEATHER ARM / OFF / TEST, the completionof the arming phase occurs when both power leversare advanced above 90% N 1 – at which time bothindicator lights on the caution/advisory annunciator