7-20 P/N 21399-004
Section 7 Cirrus Design
Airplane and Systems Description SR20
Serials 2273 & subs w/ MD302 Standby Attitude Module:
The MD302 Standby Attitude Module is mounted on the LH bolster
panel and gives backup indication of flight attitude. Bank attitude is
indicated by a pointer at the top of the indicator relative to the bank
scale with index marks at 0° (triangle), 10°, 20°, 30°, 45° (small
triangle), and 60° either side of the center mark. A fixed, user-
configurable airplane symbol is superimposed over a movable
background containing a white horizon bar that divides the attitude
display into two sections: upper “blue sky” and lower “earth”. The pitch
scale on the attitude display is graduated in 5° increments. Chevrons
appear on the pitch scale at extreme pitch attitudes. The MD302
Standby Attitude Module is electrically driven. A red X indicates the
attitude display is absent due to exceedance of internal rate sensors,
loss of airspeed, or other reasons. Redundant circuits paralleled
through diodes supply DC electrical power to the unit.
All Serials:
28 VDC for the standby attitude indicator is supplied through the 5-
amp STDBY ATTD 1 circuit breaker on the ESS BUS 1 and the 5-amp
STDBY ATTD 2 circuit breaker on the MAIN BUS 1.
Airspeed Indicator
Primary airspeed data is provided by the Air Data Computer and is
shown as a vertical tape along the upper left side of the PFD. The
airspeed scale is graduated with major tick marks at intervals of 10
knots and minor tick marks at intervals of 5 knots. Speed indication
starts at 20 knots, with 60 knots of airspeed viewable at any time. The
actual airspeed is displayed inside the black pointer. The pointer
remains black until reaching the never-exceed speed (V
NE
), at which
point it turns red. Color coded bars are provided to indicate flap
operating range, normal operating range, caution range, and never-
exceed speed. Speeds above the never-exceed speed, appear in the
high speed warning range, represented on the airspeed tape by red/
white “barber pole” coloration. Calculated true airspeed is displayed in
window at the bottom edge of the airspeed tape. Airspeed trend is also
displayed as a bar along side of the airspeed tape.
Standby Airspeed Indicator
Serials w/o MD302 Standby Attitude Module:
The standby airspeed indicator is mounted on the LH bolster panel
and displays indicated and true airspeeds on a dual-scale, internally lit
Revision A1
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