-
PTU symbols displayed in solid amber color, directed toward the Green system. The status symbol is connected to the Green and Yellow system lines. Occurs when there is a Green-engine pump low-pressure together with a PTU fault.
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PTU symbols displayed in solid green color, directed toward the Yellow system. The status symbol is connected to the Green and Yellow system lines. Occurs when there is a Yellow-engine pump low-pressure.
-
PTU symbols displayed in solid amber color, directed toward the Yellow system. The status symbol is connected to the Green and Yellow system lines. Occurs when there is a Yellow-engine pump low-pressure together with a PTU fault.
NOTE : The PTU status symbol can show when the Green (1074GK) or Yellow
____ (3074GD) engine hydraulic-pump pressure-switch sends a low pressure signal to the ECAM system. In this case, the PTU does not operate and there is no system failure.
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PTU Status Symbols on the ECAM System Display Figure 007
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Fault Indication on the PTU Pushbutton Switch Figure 008
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The FAULT light of the PTU P/BSW shows when the sensors in the hydraulic systems detect any of these conditions:
-
low fluid contents in the reservoir (Green or Yellow systems)
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low air pressure in the reservoir (Green or Yellow systems)
-fluid temperature too high (Green or Yellow systems).
The FWC also does a check of the PTU during the start of the engines. If the master switch of the engine 1 (2) is ON and the master switch of the engine 2 (1) is OFF, the PTU cannot operate. As soon as the master switches of engine 1and engine 2 are in the ON position, the PTU is can operate. If there is now a difference in the Green and Yellow hydraulic system of more than 650 psi for no less than 4 seconds, the ECAM shows a PTU FAULT indication.
**ON A/C 001-049, 051-058, 101-101,
D. Aircraft on the Ground
(Ref. Fig. 009)
To prevent unwanted operation of the PTU when the aircraft is on the ground, different switches and relays are installed in the aircraft. They operate together to supply power to the two solenoid valves (1012GL and 3012GL) under certain conditions. The PTU will not operate if:
-
the Yellow electric pump is in operation to close the cargo doors, or
-
the aircraft is on the ground, only one engine is in operation and the parking brake is ON, or
-
the aircraft is on the ground, only one engine is in operation, the parking brake is OFF and the nose wheel steering is deactivated,
-
the PTU P/BSW on panel 40VU is set to OFF.
Because the solenoid valves are energized to close them, a 28 VDC supply is necessary to automatically prevent operation of the PTU. If no supply is available, the isolation coupling prevents operation of the PTU during maintenance.
R **ON A/C 059-099, 102-149, 151-199, 201-299, 301-399, 401-499,
D. Aircraft on the Ground
(Ref. Fig. 009A)
To prevent unwanted operation of the PTU when the aircraft is on the ground, different switches and relays are installed in the aircraft. They operate together to supply power to the two PTU solenoid valves under certain conditions. The PTU will not operate if:
-the Yellow electric pump is in operation to close the cargo doors, or
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Aircraft on the Ground Inhibitions of the PTU
Figure 009
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Aircraft on the Ground Inhibitions of the PTU
Figure 009A
-
the aircraft is on the ground, only one engine is in operation and the parking brake is ON, or
-
the aircraft is on the ground, only one engine is in operation, the parking brake is OFF and the nose wheel steering is deactivated,
-
the PTU P/BSW on panel 40VU is set to OFF.
Because the solenoid valves are energized to close them, a 28 VDC supply is necessary to automatically prevent operation of the PTU. If no supply is available, the isolation coupling prevents operation of the PTU during maintenance.
POWER TRANSFER - MAINTENANCE PRACTICES
______________________________________
TASK 29-23-00-863-001
Pressurize the Green Hydraulic System from the Yellow Hydraulic System through the PTU with the Electric Pump
WARNING : MAKE SURE THAT THE TRAVEL RANGES OF THE FLIGHT CONTROL SURFACES ARE
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