(b)
Whenreinstallingsafetyandoutflowvalve,seegasketinstallationdimensions,Figure3,to insurepropergasketsealingrequirements.for proper clearancebetweennutsandgasketface,adjustclearanceasfollows: (1.) Removenutsusingdeepsocketandsufficientshimsto meet dimensionalrequirements.
A minimum of one shimis required for installation ofeach nut. (2.) Install nuts and tighten. (3.) Applydropof locking compound(MIL-S-22473-EV) nutsand
to top of nuts, between studs.
(c)
Throughtail section accessopening,installthreelocknutsholdingvalve in place;tightento metalcontactthen back off 1/4 turn.
(d)
Installaccessplateremovedfrom side of tail section.
(e)Connectlinesremovedfrom valve.
(f) Installtrim panel in frontof valves toensureacousticalmaterialisin good condition.
12. Outflowand SafetyValveCleaning
Routinemaintenancefor cabin pressurecontrolsystemcomponentsislimited to filter replacementin cabin air pressuresafetyvalve and cleaningof seats in outflow and safetyvalves.Cleanoutflow andsafety valve seatsthoroughlyusingdetergentor isopropyl alcohol.
WARNING: DRYCLEANINGSOLVENTMUSTBEUSEDINA WELL VENTILATEDAREA. AVOIDBREATHINGFUMESAND KEEP AWAYFROMFLAME.
Cleansafetyvalve filter as follows:
(a)
Removeretaining ring, onescreen,copperribbon,and remaining screenfrom filter housing.
(b)
Washbothscreens,copperribbon,andfilter housing indry cleaning solvent. Ensureorifice holein filter housingis free of foreignmaterial.
(c)
Installonescreenin filter housing.
(d)
Instalcopper ribbon infilterhousing.
NOTE: Donot over compresscopperribboninfilterhousing.
(e)
Install remianing screenand install retainingring.
NOTE: Donotcleanfilteroncontroller.Removeandreplacecomponentas required.
EFFECTIVITY:
040-999
PAGE26 21-30-00
Jan10/9021-30-00
PIPERAIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCEMANUAL
A. PressurizationControl (continued)
13. Removal of Controller
(a)
Disconnectlines from rear of cabin altitude controller assembly. Cap open parts of lines and fittingsto prevent dust from entering system.
(b)
Removescrews securing electroluminescentpanel to face of instrument panel.
(c)
Remove three screws securing selectorto instrument panels.
(d)
Remove controller by lifting assembly from rear of instrument panel.
14 Installation of Controller
(a)
From front side of panel, positioncontrollerinto instrument panel cutout.
(b)
Securecontroller to instrument panel with three screws.
(c)
Positionelectroluminescentpanelto instrument paneland secure with screws previously removed.
(d)
Removeprotectivecaps from selector linesand fittings. Connectlines to fittings on rear of controller.
15. Controller Filter Replacement
A disposable tobaccofilter, installed in the pressurization systemmust be replaced every 500 hours of normal operation. (Refer to the parts catalog for replacementfilter part number.) More frequent filter change and cleaning of the outflow and safety valve seats could be required depending on the amount of smoking in the cabin.
Replacecontrollerfilteras follows:
(a)
Removefilter,accessiblefrom underneath instrumentpanel,from behind and discard.
(b)
Installnew filter.
EFFECTIVITY:
040-999
21-30-00PAGE
21-30-OO Jan10/9027
PIPERAIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCEMANUAL
A. Heating and Cooling
The heating and cooling system uses engine bleed air to operate the environmentalcontrol system (ECS),whichin turn produces heatingor cooling to supply the cabin. Hot bleed air is used to supply heat through a bypass valve on the environmentalcontrolunit. The valve controls the amount of hot air mixed with cold air prior to entering the cabin.
1. Fault Isolation (Environmental Control System)
CHART 1 FAULT ISOLATION (ENVIRONMENTAL CONTROL SYSTEM) (Sheet 1 of 2)
Fault Cause Remedy
Bleedair leakage in primary Rupture or corrosion. Replaceheat exchanger.
or secondaryheat exchanger.
Cooling turbine will not start. Excessive air leakage. Replace seals.
Frozenbearingdue Replacecoolingturbine.
to contamination or
impropershimming.
Cooling turbine stops when Excessiveair leakage. Repairleaks.
required to run.
Water separator blockage. Coalescer cloth is iced. Checkanti-ice system.
Dirt contamination. Clean coalescer cloth.
Water separator coalescer Overtemperature. Replacecoalescercloth.
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