S
ECTION
7: A
IRPLANE
AND
S
YSTEMS
C
IRRUS
D
ESIGN
S
TALL
W
ARNING
S
YSTEM
SR20
7-66
P/N 11934-005
Stall Warning System
The airplane is equipped with an electro-pneumatic stall warning system to
provide audible warning of an approach to aerodynamic stall. The system
consists of an inlet in the leading edge of the right wing, a pressure switch
and associated plumbing.
As the airplane approaches a stall, the low pressure on the upper surface of
the wings moves forward around the leading edge of the wings. As the low
pressure area passes over the stall warning inlet, a slight negative pressure
is sensed by the pressure switch. The pressure switch then provides a signal
to cause the warning horn to sound, the red STALL warning CAS annunci-
ation to illuminate, and, if engaged, the autopilot system to disconnect.
The warning sounds at approximately 5 knots above stall with full flaps and
power off in wings level flight and at slightly greater margins in turning and
accelerated flight.
In the event of a stall warning system malfunction (e.g. ice accretion or
other contamination at the pressure port), the STALL WARN FAIL alert
will be annunciated and the aural stall warning is muted until the fault
clears.
The system operates on 28 VDC supplied though the 2-amp STALL
WARNING circuit breaker on ESS BUS 2.
Pitot-Static System
The Pitot-Static system consists of a single heated Pitot tube mounted on
the left wing and dual static ports mounted in the fuselage. The Pitot heat
is pilot controlled through a panel-mounted switch. An internally mounted
alternate static pressure source provides backup static pressure should that
the primary static source becomes blocked. Water traps with drains, under
the floor in the cabin, are installed at each Pitot and static line low point to
collect any moisture that enters the system. The traps should be drained at
the annual inspection and when water in the system is known or suspected.
Pitot Heat Switch
The heated Pitot system consists of a heating element in the Pitot tube, a
rocker switch labeled PITOT HEAT, and associated wiring. The switch and
circuit breaker are located on the left side of the switch and control panel.
When the Pitot heat switch is turned on, the element in the Pitot tube is
heated electrically to maintain proper operation in possible icing condi-
tions. The Pitot heat system operates on 28 VDC supplied through the
7.5-amp PITOT HEAT circuit breaker on NON-ESSENTIAL BUS.
Reissue A
