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

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PIPER CHEROKEE SERVICE MANUAL
VI - HYDRAULIC SYSTEM 01/31/08
2D8
6-3. TROUBLESHOOTING. Malfunctions of the hydraulic system will result in failure of the landing gear to
operate properly. When trouble arises, jack up the airplane (Refer to Jacking, Section II.) and then
proceed to determine the extent of the trouble. Generally, hydraulic system troubles fall into two types,
troubles involving the hydraulic supplying system and troubles in the landing gear hydraulic system.
Table VI-III at the back of this section, lists the troubles which may be encountered and their probable
cause, and suggests a remedy for the trouble involved. A hydraulic system. operational check may be
conducted using Figures 6-1 or 6-2. When the trouble has been recognized, the first step in trouble-
shooting is isolating the cause. Hydraulic system troubles are not always traceable to one cause. It is
possible that a malfunction may be the result of more than one difficulty within the system. Starting first
with the most obvious and most probable reasons for the trouble, check each possibility in turn and, by
process of elimination, isolate the troubles.
NOTE: If it is found that the hydraulic pump is at fault and requires disassembly, it is recommended that
it be overhauled by a recommended overhaul shop. However, if this cannot be achieved, minor
repairs of the pump such as replacement of gaskets and motor components, and pressure checks
with adjustments maybe accomplished in accordance with instructions given in paragraphs 6-6
thru 6-9.
6-4. HYDRAULIC PUMP
6-4a. ORIGINAL EQUIPMENT PRESTOLITE PUMP, P/N 96671-002 ONLY.
6-5. REMOVAL OF HYDRAULIC PUMP. The hydraulic pump with reservoir incorporated is located in the
aft section of the fuselage. Access to the pump is through the access panel in the aft wall of the baggage
compartment.
a. Disconnect the pump electrical leads from the pump solenoid relays and the ground wire from the
battery shelf.
b. Disconnect the hydraulic lines from the pump. Cap the line ends to prevent contamination.
c. Remove the pump by removing the pump attaching bolts.
TABLE VI-I. LEADING PARTICULARS, HYDRAULIC SYSTEM
Hydraulic Pump 96671-002 (Prestolite) 38998-004 (Oildyne)
High Pressure 1600 to 2000 psi 2400 ± 200 psi
Low Pressure 650 ± 150 psi 600 ± 200 psi
Flow Rate @ 1000 psi 45 cu. in. per min. 60 cu. in. per min.
High Pressure Control 1600 to 2000 psi 2400 ± 200 psi
Thermal Relief 4000 psi 3000 +300, -200 psi
Hydraulic Fluid MIL-H-5606 MIL-H-5606
Pressure Switch
Open (OFF) Pressure 1100 ± 100 psi 1800 ± 100 psi
Close (ON) Pressure 400 ± 200 psi below 300 ± psi below
opening pressure opening pressure