BRAKES.......................................................................................... 11
Automatic Brake System (ABS) ................................................. 12

Continental
Rev. 12/01/00 #29 Flight Manual
INTENTIONALLY LEFT BLANK

HYDRAULICS

General
The airplane has two independent hydraulic systems utilizing fire-resistant hydraulic fluid. Each system has a reservoir and is pressurized by a single engine-driven pump. Ground service provisions for each system are located in the main gear wheel wells. These include a ground service connection panel, a hand pump for building pressure for ground maintenance operations, and a spoiler shutoff and system depressurization valve.
Hydraulic Reservoir
The left and right hydraulic system reservoirs are located in left and right main gear wheel wells, respectively. Each reservoir supplies fluid to its own system exclusively. A manifold on the bottom of the reservoir ports fluid to supply lines for the engine-driven pump, the electrically-driven auxiliary hydraulic pump, and a ground service hydraulic hand pump. Internally, the reservoir utilizes system pressure of 3000 or 1500 psi to maintain a pressure head of approximately 30 or 15 psi. This pressure head ensures positive transfer of fluid to the pumps. The reservoir is protected against over-pressurization by a relief valve set for 47 psi. A temperature pick up in the reservoir will cause the applicable (L or R) HYD TEMP HI annunciator light to illuminate when hydraulic fluid temperature is above normal. An instruction plate provides filling instructions and direct fluid level indications for both system pressurized and unpressurized conditions. A fluid quantity transmitter, located at each reservoir, transmits fluid quantity information to the applicable hydraulic quantity indicator on the First Officer’s instrument panel.
Hydraulic Pumps
The left hydraulic system is pressurized by a system pump mounted on the left engine; a system pump mounted on the right engine powers the right system. Each pump is capable of providing pressure to 3000 psi during all flight modes; 1500 psi can be selected for cruise flight operation.
An auxiliary pump, incorporated into the right system, provides hydraulic pressure for landing gear operation, flight backup, preflight, and maintenance operations. The pump is electrically powered and is designed for continuous operation at 3000 psi.
Continental
Rev. 12/01/00 #29 Flight Manual
A power transfer unit mechanically connects left and right hydraulic system and enables hydraulic pressure to be transferred from the highest to the lowest side (the high pressure side operates as a motor and the low pressure side operates as a pump). The unit is controlled by a single motor operating two shutoff valves, one in each hydraulic system. Operation is controlled by a switch on the First Officer’s instrument panel. The shutoff valves will automatically close if either system reservoir quantity falls below a safe level.
Airplane systems that normally receive pressure from both hydraulic systems will operate at a reduced rate if one system is inoperative. Complete fluid supply to a system can be stopped by pulling the fire shutoff handle on the upper instrument panel for the engine desired. Pump operation is controlled by switches on the First Officer’s instrument panel. Annunicator panel lights, one for each system, will illuminate whenever either system pressure is low.
A hand pump, installed in each main hydraulic system and located in the main gear well, supplements the standard power sources for ground actuation of the various subsystems. The quick disconnect fittings in the inlet suction line of each hand pump and/or auxiliary pump may be connected to a ground source of hydraulic fluid to manually fill the reservoirs. These pumps make the hydraulic systems completely self-sufficient. Hydraulic ground connections are provided in the forward end of each main gear well for servicing and testing each main hydraulic system.
MD-80 Sec. 14 Page 3
Flight Manual Continental Rev. 12/01/00 #29

LEFT ENGINE
HYD PUMP
GROUND LEFT HYD CONTROL SYSTEM
LEFT
THRUST
 REVERSER

L and R INBOARD FLIGHT SPOILER
ELEVATOR BOOST
MD801401
ELECT
MOTOR

AUX
HYD PUMP

POWER
 TRANSFER UNIT

M/P M/P

RIGHT 
ENGINE 
HYD 
PUMP 
RIGHT GROUND 
 HYD SYSTEM  CONTROL 
RIGHT 
THRUST 
REVERSER 
L and R 
OUTBOARD 
FLIGHT SPOILER 

MANUAL REVERSION  RUDDER 
SLATS 
FLAPS 
GROUND SPOILERS 
NOSEWHEEL STEERING 
BRAKES ANTI-SKID 
FREE FALL  LANDING GEAR 
VENTRAL STAIRWAY 
　
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