Leading Particulars, Hydraulic System - Piper PA-44-180 SEMINOLE Maintenance Manual

TO PREVENT THE BUILDUP OF UNNECESSARY
PRESSURE ON THE ACTUATING CYLINDERS AND
CONNECTING HYDRAULIC LINES, WHEN THE GEAR
IS RAISED OR LOWERED MANUALLY WITH THE
AIRPLANE ON JACKS, PULL THE EMERGENCY
EXTENSION KNOB OUT. FAILURE TO COMPLY WITH
THIS PROCEDURE COULD RESULT IN THE BUILDUP
OF SUFFICIENT PRESSURE TO UNLOCK THE D O W N
LOCK, ALLOWING THE GEAR TO COL L A P S E
WHEN THE WING JACKS ARE REMOVED. PRIOR TO
REMOVING THE AIRPLANE FROM THE JACKS, PUSH
THE EMERGENCY EXTENSION KNOB IN, TURN THE
MASTER SWITCH ON, AND SELECT GEAR DOWN.
O B S E RVE THAT ALL THREE GREEN LIGHTS ARE
ENERGIZED, INDICATING THAT THE LANDING
G E A R S A R E D O W N A N D L O C K E D . T U R N T H E
M A STER SWITCH OFF.
CHART 2901. LEADING PARTICULARS, HYDRAULIC SYSTEM
HYDRAULIC PUMP
Hydraulic Pump
High Pressure
Low Pressure
Flow Rate @ 1000 psi
Hydraulic Fluid
Thermal Relief Valve
Shuttle Valve Delivered
Pressure
Pressure Switch
Open (OFF) Pressure
Close (ON) Pressure
TROUBLESHOOTING.
Malfunctions in the hydraulic system will result in failure of the landing gear to operate properly. When
trouble develops, jack up the airplane (refer to Chapter 7) and then proceed to determine the extent of the trou-
ble. Generally. hydraulic system troubles fall into two types, troubles involving the hydraulic supplying system
and troubles in the landing gear hydraulic system. Chart 2902 lists the troubles which may be encountered and
their probable cause and suggests a remedy.
If it is found that the hydraulic pump is at fault and requires
d i sa s s e m b l y, it is recommended that it be overhauled by an
accredited overhaul facility. Pressure checks with adjustments
may be accomplished in accordance with instructions given.
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
— CAUTION —
HYC5005
PRESTOLITE
2000 to 2500 psi
650 ± 150 psi
45 cu. in. per min.
MIL-H-5606
2250 ± 250 psi.
400 - 800 psi
1800 ± 100 psi
200 to 400 psi
— NOTE —
2B24
Piper P/N 481 879
OILDYNE
2400 ± 200 psi
600 ± 200 psi
60 cu. in. per min.
MIL-H-5606
3000 + 300 / -200 psi
400 - 800 psi
1800 ± 100 psi
300 ± 100 psi
29-02-00
Page 29-05
Revised: June 20, 1995