**ON A/C 001-049, 051-051, 056-056, 058-099, 101-105, 151-199, 201-299,
B. Vacuum Generator 37MG
(1) The vacuum generator is connected to the aircraft power circuit through the motor starting relay (36MG). The generator operates:
-At ground level and up to an altitude of 4877 m (16000 ft.) (the altitude pressure switch stays closed. It sends an electrical signal to the VSC to operate the vacuum generator).
-When the toilet flush switch is operated (the FCU sends an electrical signal to the VSC which energizes the motor starting relay). This supplies power to the vacuum generator.
NOTE : After 15 seconds the motor start relay is isolated and
____ electrical power to the generator is stopped.
(2) Vacuum generator overheat protection: The VSC monitors the thermal switch circuit (overheat protection) of the vacuum generator. When an overheat occurs the thermal switch opens. This sends an electrical signal to the VSC and stops electrical power to the vacuum generator.
C. Altitude Pressure Switch 43MG The altitude pressure switch is connected electrically to the VSC and operates:
-At ground level and altitudes up to 4877 m (16000 ft.) the altitude pressure switch stays closed
-Above 4877 m (16000 ft.) the altitude pressure switch stays open
-During altitude descent the switch closes at 3658 m (12001 ft.). The VSC monitors when the altitude pressure switch is open or closed.
D. Landing Gear Signal One of the functions of the Landing Gear (LG) signal is to give the indication to the VSC (that the aircraft is on ground and the strut is compressed). The LG signal is also used as a back up for other primary indications. In general a single LG fault will have no effect on the vacuum waste system. The VSC will not generate a fault message if the LG signal is faulty, because the VSC BITE does not control the LG signal.
R 1EFF : 001-049, 051-051, 056-099, 101-149, 1 38-31-00Page 41 1151-199, 201-299, 301-399, 401-499, 1Aug 01/05 1 1 1CES 1 **ON A/C 052-055, 057-057,
