Piper Aircraft Corporation Cherokee 140 PA-28-140, Service Manual

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PIPER CHEROKEE SERVICE MANUAL
VI - HYDRAULIC SYSTEM 01/31/08
2E2
c. To check adjustment of electrical switch, the following procedure may be used:
1. Place the airplane on jacks. (Refer to Jacking, Section II.)
2. Move the mixture control back to idle cut-off and the throttle to full forward to prevent gear
warning horn from sounding during adjustment.
3. Ascertain that the actuator tension springs are properly adjusted according to Step a.
4. Retract the landing gear hydro electrically by turning the master switch ON, raising the
emergency gear extension lever and moving the gear selector handle to the up position. The
emergency gear extension lever must be retained in the up position to keep the gear up.
5. Check for proper switch operation by the following procedure:
(a) Turn master switch ON and move gear selector handle to the up position. Pump should not
operate.
(b) Move the emergency gear extension lever to the up override position. Pump should operate
and gear should retract.
(c) With selector lever up, slowly lower emergency gear extension lever to allow gear to drop
to down position. The pump should not operate at any time during extension.
(d) Turn master switch OFF.
6. Check gear operation in the normal manner with the use of the gear selector handle. The
emergency extension lever must be held in the up override position.
7. Ascertain that gear is down and locked and remove airplane from jacks. Then flight check the
retractable landing gear system. (Refer to Paragraph 6-16.)
6-16. OPERATIONAL CHECK OF RETRACTABLE LANDING GEAR SYSTEM.
a. Maximum Gear Extend: Place the gear selector in the down position at 150 MPH (130 Kts). In
approximately 5 to 10 seconds the three green gear lights should be on indicating that the gear is
down and locked.
b. Minimum Gear Retract: Allow approximately 8 seconds for the pressure in the hydraulic system to
normalize between gear extension and retraction. Place the selector switch in the UP position at 125
MPH (109 Kts). In approximately 5 to 10 seconds all the gear indicating lights should be out,
indicating that the gear is fully retracted.
c. Override Gear Down and Up:
1. Down: Establish a normal glide at approximately 120 MPH (104 Kts), with power at idle.
Slowly move the override lever down, while observing the ammeter to confirm that the
hydraulic pump does not start. The gear should go down and lock. Move the gear selector
switch down. Release the override lever. The gear should remain down.
2. Up: Set maximum climb power. Maintain approximately 70 MPH (61 Kts) for approximately
15 seconds. Move the gear selector switch to the up position. The gear should not retract. Pull
the override lever up. The gear should retract. Allow the airspeed to increase to at least 120
MPH (109 Kts). Release the override lever and the gear should remain up.
d. Gear "Back-Up" Down and Up:
1. Gear Down: Set power at idle. Glide the aircraft at 120 MPH (109 Kts). Decrease the airspeed
at the rate of 1 MPH (1 Kt) per second. The gear should start down between. 100 and 110
MPH (87 to 96 Kts). Place the gear selector switch down, after the gear is down and locked.