Stall Warning System - Cirrus DESIGN SR20 Information Manual

Cirrus Design Section 7
SR20 Airplane Description

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, and a piezo-
ceramic horn behind the instrument panel. 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 sense inlet, a slight negative
pressure is sensed by the pressure switch. The pressure switch
completes a ground circuit causing the warning horn to sound. The
warning horn provides a 94dB continuous 2800 Hz tone. 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. The system operates on 28 VDC supplied though
the 2-amp STALL WARNING circuit breaker on the Essential Bus.
With battery power on, the stall warning system preflight check is
accomplished as follows:
Stall warning system preflight check:
1. Use small suction cup and apply suction. A sound from the
warning horn will confirm that the system is operative.
P/N 13999-002 Info Manual 7-65
September 2011