27-30-00
Jan 10/90

PIPERAIRCRAFT
PA-42-720(Advanced Trainer)
MAINTENANCEMANUAL

A. ElevatorandTab(continued)
21.Removalof Trim Controls(continued)
(c) Removeandinstalltheaileron and ruddertrimcontrolmechanismasfollows:
(1.) Removepilotseatandtwoaccessplateson side of pedestal.
(2.) Removeclevispin connecting controlmechanismshaftto universal joint.
(3.) Withcontrolwheelremoved,unscrewthree indicator retainingscrews.Removeindicator.
(4.) Removemountingscrewsandpull assembly from pedestal.
(5.) Reinstallremovedassemblyin reverse order,ensuringindicatoris alignedin neutral.

22. Installationof Trim Controls(Figure402)
(a) Instalationof aileron andruddertrimcontrolmechanismas follows:
(1.) Installremovedassembly,ensuringindicatoris aligned in neutral.

(2.) Lay assembly intopedestalandinstallmountingscrews.
(3.) Withcontrolwheelremoved,installthethreeindicatorretainingscrews,installingindicator.
(4.) Installclevispinconnectingcontrolmechanismshaftto universal joint.
(5.) Installpilotseatandtwoaccessplateson sideofpedestal.

(b) Installelevatortrimcontrolas follows:
(1.) Installindicator,ensuringindicatoris aligned properly.
(2.) Installfourmountingscrewsandlayl control assemblyinto control pedestal.Pull forward cablesystemthroughaircraft,connect,andblock(describedin paragraph onRemovalof the Forward ElevatorTrimSystem).
(3.) Install sixretainingscrewsholding indicator plateto the controlhub assembly. Install control wheel.
(c) Carefullyplacewheel/knobonto shaft. Installflushheadset screw retainingcontrolknobor wheelto splined shaft.
23.Adjustmentof Trim Indicators
(a)
Ensure indicator mechanismmovesfreelyand is properly lubricatedaccordingto Lubrication Chartsin 12-20-00.

(b)
Maintaintrim tabs at controlsurfacesin neutral.

(c)
Ensure trim drumsare at neutralpositions.

(d)
Proceedasfollows if trim indicators are not aligned with neutralmarkeron pedestal:

(1.) Removetrimcontrolwheelfromshaft.
(2.) Loosenthreescrewsholdingindicatordiscsto indicator mechanism.
(3.) Rotate discsrightorleft to align neutral positionofdiscswith marker on pedestal.
(4.) Tightenthree screws. Replacetrimcontrol wheel.

NOTE: For ELEVATORBALANCINGPROCEDURE,referto 55-20-00.
EFFECTIVITY:

PAGE14
040-999

Jan10/9027-30-00
PIPERAIRCRAFT
PA-42-720(Advanced Trainer) MAINTENANCEMANUAL

A. Elevatorand Tab (continued)
RudderTrim Control 
NOTE: Safety wire roll pin through shaft. Snug tie off against shaft using cautionto avoid interference with mechanism. Trim Position -Indicator Gear-

TrimControlInstallation
Figure 402

EFFECTIVITY: 040-999
27 30-00PAGE
27-3O 15

-00 Jan 10/90
PIPER AIRCRAFT

PA-42-720 (Advanced Trainer) MAINTENANCE MANUAL
A. ElevatorandTab(continued)
24.StallWarning/RecognitionSystem
The stall indicating system in the PA-42-720 containstwo,identicalsafe flight SC-200 stall
recognitionsystems, independent of each other, power, or aircraft configuration. Each system, one
for the pilot the other for the copilot, uses a heated wing mounted lift transducer, a remote lift
computer,a stall warning horn, a stall recognitionhorn,a lighted placard, and a test switch.
The electro-mechanical lift transducer, mountedto the lowerleadingedge of the wing, senses the
existingpositionofthe leading edge stagnation point through the spring loadedvane.The
appropriatesignalis sent to the computer so when the vane is forced aft, the stall warning horn is
activated,and when the vane is forced forward, the stall recognition horn and lighted placardare
activated.
The lift computeris located in the avionics bay, forward of Fuselage Station 57.0 pressure
bulkhead. Signals from the transducer are conditioned bythe computer whichactivatesthe stall
warningor recognition system through a two-level output.A self monitoring circuit in the computer
activatesa warning light if any essential internal or external power is lost.
The stall warning system contains a separate horn and a lighted placard. The stall recognition
horn, also mounted in the headliner, emits a loud,pulsatingtone different than the stall or gear
warning horns. The lighted placard (STALL), mountedin the edge of the glareshield, is keyed
simultaneously horn.
with the recognition
A single test switch is mountedon the instrument panel below the fire warning light/switches. On
the ground, activationof the switch bypasses theright gear squat switch,turns on the computer,
and slews the transducer vane upward. This provides the necessary signals to activatethe horns
　
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