Specifications

7-64 P/N 13999-002 Info Manual
Section 7 Cirrus Design
Airplane Description SR20
Suction Gauge
The suction gauge, located on the far right side of the instrument
panel, is calibrated in inches of Mercury (Hg). The gauge indicates
suction available for operation of the attitude and directional gyros.
The desired suction range is 4.5 to 5.4 inches of Hg. A suction reading
out of this range may indicate a system malfunction or improper
adjustment. The attitude and directional indicators should not be
considered reliable when the suction gauge indicates out of range.
• Note •
The attitude GYRO flag will drop if the attitude indicator is not
receiving adequate vacuum for operation.
Vacuum Warning Light
Illumination of the red VACUUM warning light in the annunciator panel
indicates failure of the engine driven vacuum pump or that the
airplane's engine is not operating. A vacuum switch in the vacuum line
between the engine-driven vacuum pump and the vacuum manifold
illuminates the VACUUM warning light on low vacuum in the line. In
addition to illuminating the VACUUM warning light, the switch also trips
a relay energizing the back-up electric vacuum pump. This condition
exists whenever the BAT Master switch is on and the engine is not
operating (such as before start) or in the event the engine-driven
vacuum pump fails. The VACUUM warning light operates on 28 VDC
supplied through the 2-amp ANNUNC PWR circuit breaker on the
Essential Bus.
Aux Vac Caution Light
Illumination of the amber AUX VAC caution light in the annunciator
panel indicates that the electric (back-up) vacuum pump is supplying
vacuum. A vacuum switch in the vacuum line between the electric
vacuum pump and the vacuum manifold illuminates the light on rising
vacuum in the line. Normally, the light will be illuminated whenever
electrical power is on the airplane and the engine-driven vacuum
pump is not operating. The AUX VAC caution light operates on 28
VDC supplied through the 2-amp ANNUNC PWR circuit breaker on
the Essential Bus.
September 2011