Cirrus SR20 Pilot Operating Handbook page 206

Section 7 Cirrus Design
Airplane and Systems Description SR20
Standby Altimeter
Serials w/o MD302 Standby Attitude Module:
Airplane altitude is depicted on a conventional, three-pointer, internally
lit barometric altimeter installed on the LH bolster panel. The
instrument senses the local barometric pressure adjusted for altimeter
setting and displays the result on the instrument in feet. The altimeter
is calibrated for operation between -1000 and 20,000 feet altitude. The
scale is marked from 0 to 10 in increments of 2. The long pointer
indicates hundreds of feet and sweeps the scale every 1000 feet (each
increment equals 20 feet). The short, wide pointer indicates thousands
of feet and sweeps the scale every 10,000 feet (each increment
equals 200 feet). The short narrow pointer indicates tens of thousands
feet and sweeps from 0 (zero) to 2 (20,000 feet with each increment
equal to 2000 feet). Barometric windows on the instrument's face
allow barometric calibrations in either inches of mercury (in.Hg) or
millibars (mb). The barometric altimeter settings are input through the
barometric adjustment knob at the lower left of the instrument.
Serials 2273 & subs w/ MD302 Standby Attitude Module:
The MD302 Standby Attitude Module is mounted on the LH bolster
panel and displays the current barometric corrected altitude. The
instrument senses the local barometric pressure adjusted for altimeter
setting and displays the result in the Altitude Window. The altitude
units are user-configurable in feet or meters. The Altitude Window/
Pointer sweeps the altitude tape and denotes the current BARO-
corrected altitude. The BARO Window shows the currently selected
barometric altitude. The BARO units are user-configurable in IN HG or
MBAR. The barometric setting on the MD302 will automatically
synchronize to the setting on the Garmin avionics, and can be
manually adjusted by turning the Control Knob while in Flight Mode.
28 VDC for the MD302 Standby Attitude Module 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.
All Serials:
The standby altimeter does not have automatic position error
corrections, calibration corrections are necessary. Because the PFD
has automatic corrections and the standby does not, differences
between the two indications are typical (difference is the greatest at
high altitudes and high airspeeds, where the position error corrections
are the highest).
7-22 P/N 21399-004
Revision A1