(e)
Removeoldwiper strip from housing andclean and inspect the housingto ensure no pieces remain.

(f)
Wipepiston tube and check It for any abrasions whichcould damage thenew wiper. Polish tube to remove any abrasions.

16.InstallationofWiper Strip on Gear Strut
(a)A new wiper strip must be cut with a 30 degree bevel, a little longer than needed, to circle the piston tube.
(b)
Insertnew wiper strip up into the oleo housingwith the tapered edgedown.Slide the retainer washerand snap ring up the piston tube. Insertthem into the oleo housing.Usingsnapringpliersto compress thesnapring, install it into the annular slot in the oleo housing.

(c)
Inflate the oleo strut according to instructionsgivenin Oleo Struts (refer to 12-10-00).Remove airplanefrom jack.

17.Removalof Nose GearDoor Assembly
(a)
To remove gear door, disconnectretractionrod at the door and remove hingebolts at each side of the wheel well.

(b)
Toremovedoorretractionmechanism,besure retraction rod is disconnected.Disconnectthe down lock spring and removethe snap ring holding the retraction mechanismon its support shaft. Pull the retraction mechanismfromshaft.

18.Installationof Nose Gear Door Assembly
(a)To install the door retraction mechanism, positionand bolt unit in place. Connectthe down lock spring.
(b)Thegear door is installed by aligning thebracket bolt hole with the hinge, installing bolt assemblyandsecuringit. Attach and secure theretractionrod.
EFFECTIVITY:

040-999 Jan10/90 32-20-00
PIPERAIRCRAFT
PA-42-720(Advanced Trainer)
MAINTENANCEMANUAL

A. NoseGear and Doors(continued)
19. Adjustmentof Nose Gear Door Assembly
(a)
Checkthat nose landing gear is properly adjusted.

(b)
With gear up and locked, close one door at a time and adjust door operating rods until bolts canbe freely inserted. Shortenrods one full turn of rod end bearings. Do not install bolts.

(c)
Extend gear and install door operating rod bolts. Adjust door open stop bolts, allowing door linkageto pass 0.060to 0.120 inches throughcenter.

(d)
Retract the gear slowly. Ensureall parts are operating satisfactorily.

(e)
If gear fails to remain retracted after the cockpit handle returns to neutral, it is necessary to readjusteitheror both the following items until gear locksup:

(1.) Increaseactuator stroke by turning out the stroke controlstop.
(2.) Relieve door pinch by lengthening thedooroperatingrods.
20. Inspectionof Nose Gear Door Assembly
(a)
Inspectdoor for cracks or bent skin,loose hinge brackets, and worn or corroded bearings.

(b)
Checkretractionmechanism for a worn down lock spring and worn or damaged surfaces.

21.
Cleaning of Nose Gear Door Assembly

Cleanall parts with a suitable cleaningsolvent.

22.
Repair of Nose Gear Door Assembly

Repair to the door assemblyis limited to replacing hinge bearings, rivets, mechanism parts,minor skin repairs, and repainting.
EFFECTIVITY:
040-999 32-20-00 Jan 10/90
PIPER AIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL

A. ExtensionandRetraction
(1) Descriptionand Operation
The nose gear retracts aft into the nose section,pullingmechanicallyinterconnectedgear doors
closed. The main landing gears retract inboardinto each wing and are covered by hydraulically
actuateddoors and those mechanically connected to each gear.
The gear operatingmechanismsuse two systems. The primary systemuseshydraulicpower
during normal operationsandis covered in Chapter 29. A secondary or redundant system,
incorporatedinto each gear operatingmechanism,providesa way of extending the required gearif
any part of the hydraulic systemfails. The secondarysystem,incorporated as an emergency
backupfor the hydraulicsystem,onlymoves the affected gear to the down position.
The landing gearoperating controls are located on the pilot's side of the instrument panel. The gear selector, with the indicator lights to its right, is situated on the bottom of the panel directly underthe column of engine instruments.Theemergencyextensionbutton is also mounted on the pilot's side of the instrumentpanel, just below the oxygen pressuregauge,to the right of the alternatestaticsourceselector.
Two means of emergency extensionare available. The emergency extension(blowdown)system
(EES) (refer to 32-30-00 Figure 1) employs a logic circuit which senses gears not extended.
When the button is pushed, the remaininggears are extended and locked in place. The system
works so if one or more gears fail to extend and the emergency extension buttonis pushed, the
logic relay allows electrical powerto ignite an explosive charge on the affectedgear's system.
　
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