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HYDRAULIC INDICATING SYSTEM -TEMPERATURE INDICATING
BEJ ALL POST SB 777-29-0024 (Continued)
For the EDP and ADP temperature transducers, an electrical signal of less than 1 milliampere or more than 23 millamperes indicates a transducer fault.
For the ACMP temperature transducers, an electrical signal of less than 1 milliampere or more than 40 millamperes indicates a transducer fault.
The ACMP temperature switch closes at approximately 105C and reopens at approximately 75C. When the temperature switch closes, it connects a fixed resistor between structure ground and the ACMP temperature transducer input on the HYDIM card. The fixed resistor provides an electrical signal of approximately 17 milliamperes to the HYDIM card. This electrical signal will cause the HYDIM card to detect an ACMP overheat condition independent of the signal provided by the case drain temperature transducer. If the transducer and the switch detect an overheat at the same time, then the total signal provided to the HYDIM card will be between 33 and 40 milliamperes.
BEJ ALL
These advisory messages show if a transducer fault is detected continuously for 30 seconds:
*
HYD TEMP IND PRI L
*
HYD TEMP IND PRI C1
*
HYD TEMP IND PRI C2
*
HYD TEMP IND PRI R
*
HYD TEMP IND DEM L
*
HYD TEMP IND DEM C1
*
HYD TEMP IND DEM C2
*
HYD TEMP IND DEM R
The messages go away if the fault is not detected for 3 seconds.
Hydraulic Pump Temperature Indication
Hydraulic pump temperatures are shown on the hydraulic maintenance page in degrees C.
The applicable hydraulic pump temperature display will be blank if a temperature transducer fault is detected.
These advisory messages show if a pump temperature is more than 105C for 2 seconds:
*
HYD OVERHEAT PRI L
*
HYD OVERHEAT PRI C1
*
HYD OVERHEAT PRI C2
*
HYD OVERHEAT PRI R
*
HYD OVERHEAT DEM L
*
HYD OVERHEAT DEM C1
*
HYD OVERHEAT DEM C2
*
HYD OVERHEAT DEM R
The messages go away when the pump temperature is less than 75C for 1 second.
EFFECTIVITY BEJ ALL 29-30-00
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D633W101-BEJ Sep 05/2003
HYDRAULIC INDICATING SYSTEM -TEMPERATURE INDICATING
These status messages also show for a pump overheat condition:
*
HYD PUMP PRI L
*
HYD PUMP PRI C1
*
HYD PUMP PRI C2
*
HYD PUMP PRI R
*
HYD PUMP DEM L
*
HYD PUMP DEM C1
*
HYD PUMP DEM C2
*
HYD PUMP DEM R
The status message faults are latched in the HYDIM card and are reset when the pump operating conditions return to normal. The messages go away when the pump temperature is less than 100C with normal pump pressure for 10 seconds (for the EDPs) or 60 seconds (for the ACMPs and ADPs).
These indications also show for a pump overheat:
*
Fault light on P5 hydraulic/RAT panel
*
OVHT next to the pump symbol on the hydraulic synoptic display.
For more information about the hydraulic system displays, see .
BEJ ALL POST SB 777-29-0024
Training Information Point
For some operating conditions, an ACMP temperature transducer fault can be reported as an ACMP overheat message.
The HYDIM cards allow a larger range of valid ACMP temperature signals because of the ACMP temperature switch circuit. A closed temperature switch must be reported as an overheat condition because an overheated hydraulic pump can prevent dispatch. The electrical signal from the switch circuit, added to the electrical signal from an operational temperature transducer, is still considered a valid signal.
If the ACMP temperature transducer has a fault that results in an electrical signal larger than the actual temperature but not large enough to be considered invalid, then an ACMP overheat message can show instead of an ACMP transducer message.
BEJ ALL
Hydraulic Reservoir Temperature Indication
Reservoir temperature in degrees C shows on the hydraulic maintenance page. There are no reservoir overheat indications.
EFFECTIVITY BEJ ALL 29-30-00
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HYDRAULIC INDICATING SYSTEM -TEMPERATURE INDICATING
CAUTION: DO NOT OPERATE THE HYDRAULIC PUMPS AFTER THE TEMPERATURE INDICATION ON EICAS IS MORE THAN 100C (212F) OR AFTER THE PUMP FAULT LIGHT COMES ON. IF YOU CONTINUE TO OPERATE THE PUMPS, THE HYDRAULIC FLUID CAN BECOME TOO HOT.
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