Pitot-Static System; Pitot Heat Switch; Pitot Heat Light; Alternate Static Source - Cirrus DESIGN SR20 Information Manual

Cirrus Design Section 7
SR20 Airplane Description

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 conditions. Pitot heat should be used only when
required. The Pitot heat system operates on 28 VDC supplied through
the 7.5-amp PITOT HEAT/COOLING FAN circuit breaker on the Non-
Essential Bus.

Pitot Heat Light

Illumination of the amber PITOT HEAT caution light indicates that the
Pitot Heat switch is in the 'on' position and the Pitot heater is not
receiving electrical current. A current sensor on the Pitot heater power
supply wire provides current sensing. The PITOT HEAT warning light
operates on 28 VDC supplied through the 2-amp ANNUN circuit
breaker on the Essential Bus.

Alternate Static Source

An alternate static pressure source valve is installed on the switch and
control panel to the right of the pilot's leg. This valve supplies static
pressure from inside the cabin instead of the external static port. If
erroneous instrument readings are suspected due to water or ice in
the pressure line going to the standard external static pressure source,
the alternate static source valve should be turned on. Pressures within
the cabin will vary with open heater/vents. Whenever the alternate
P/N 13999-002 Info Manual 7-61
September 2011