A. Flaps (continued)
MeasureStep in tooth form
Checkingfor Worn Gear Wear Figure 602
15. Removalof Flap Control Box (Selector)
(a)
Removethe knob from the control box.
(b)
Removethe electricalconnectorfrom the rear side of the control box.
(c)
Removethe two screws that secure the controlbox to the instrument panel.
(d)
Removethe controlbox from the instrumentpanel.
16. Installationof Flap Control Box
(a)
Installthe flap control box in the instrumentpanel.
(b)
Installthetwo screws that securethe control box.
(c)
Connectthe electrical leads.
(d)
Installthe knob.
17. Removalof Flap ControlAmplifier
(a)
Openaccessdoorin nose of airplaneto gainaccessto amplifier at F.S.25.60.
(b)
Disconnectthe electricalplugfromthe amplifier.
(c)
Removethe attaching screwsandremovethe amplifier from the airplane.
18. Installationof Flap Control Amplifier
(a)
Installcontrolamplifier in airplane andsecurewith attaching screws.
(b)
Connect the electricalplugto the amplifier.
(c)
Checkrigging and adjustmentof flaps.
(d)
Closeandsecureaccess door.
EFFECTIVITY:
040-999 27-50-00
Jan10/90
PIPERAIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL
A. Flaps (continued)
19. RiggingandAdjustmentof Flaps
The rigging procedurefor this wing flapsystemis both mechanical and electricaland requiresthat
the landing gearbe raisedor squat switchesin the left main gearbe madeto the in-flightposition.The controlsystem,in addition to providingproportionalpreselect,also incorporates circuitryfor systemshut-downin the eventof anyasymmetricalflapconditionof five degrees,and controlof flaptransmissionstrokelengthin both extendand retractpositions. Themaincomponentsof the
controlsystemare:a controlamplifierthat suppliesvoltagefor and receivessignalsfromthree
separatereostatsusedin the system. Two of threereostatsare linked (oneto the left and one to the right)wingflap assembliesin such a manor asto sense flap position.The thirdrheostatis locatedin the wingflappositionselectorandis the control for flap positioning.Thefollowing
abbreviationsare usedin description andserviceinformationpresentedin the following
paragraphs:
RC-ControlPotentiometerWiperat Selector.
RL- Left WingFlapPotentiometerWiper.
RR- Right Wing FlapPotentiometerWiper.
A VCL-Voltagedifferencefrom(RLto RC -.10).X2 in the up position.
A VCR-Voltagedifferencefrom (RCto RR-.10) x 2 in the up position.
RequiredEquipment
DigitalVoltmeter(10 milliamp Scale)
Rig Boardflaptools (P/N71505-16and71505-17)
WorkSheet(Figure 603)
WARNING: ALLADJUSTMENTSMUSTBE MADEWITHMOTORPOWEROFF.
All adjustmentsare madewith motorcircuitbreakerpulledOFFandflaps in DOWNposition.
Adjustmentproceduresrequirespecialequipmentsuchas a digital voltmeterand flap rigging tool (P/N71505-16and -17).
CAUTION: ELECTRICALPOWERTO SYSTEMMUSTBEOFF. PULLFLAPCONTROLAND MOTORCIRCUITBREAKERS,SETBATTERYMASTERSWITCHOFF, AND DISCONNECTEXTERNALPOWER.
Thecontrolpotentiometeroperatedby the flap selectoris referredto throughoutthe rigging
procedureas RC (potentiometercontrol). Thewingflap potentiometers aredesignatedas RL
(potentiometerleft) and RR(potentiometerright). Thevoltagesat the center taps are referred to
as VC, VL, and VR respectively.
Proper operation after riggingrequirespotentiometerRL on the leftflapmustrespondto changes
in flap position selectorpotentiometerRCin VL and VC. Amountof stroketravelandhow it is
centeredwith respect to endsis determined by how RLis adjusted relativeto RC. SinceVC is
fixed and cannotbe changed,trimmerpot RT2, providedin the controlamplifier,allowsadjustment
of VL to agree with VC.
Throughoutadjustmentprocedures,whateverchangesare made to RL and RT2mustalso be
made to RR and RT3. RRtracks RL overentirestrokerangeandshutssystemoff if VL andVR
outputs deviate by morethan 0.5 volts. Thisvoltagedifferentialcorrespondsto a five-degree
asymmetricalflap condition. RR also provides a voltageinputto the controlamplifierto give an
outputto theflap position indicator.
NOTE:Adjustmentsof RL, RR,RT2,andRT3 are always madewithflapsdown.Themagnitudeof these adjustments,basedon values ofVC,VL,and VR, are measured withflapsup.
EFFECTIVITY: PAGE14 040-999
Jan10/9027-50-00
PIPER AIRGRAW
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL
A. Flaps (continued)
19. Riggingand Adjustment of Flaps (continued)
Cut through the0.500AND 0.562
disc and socket toSockets needed permit it to slide to cover two size overthe pot shaftjamnutson dots
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