S
ECTION
7: A
IRPLANE
AND
S
YSTEMS
C
IRRUS
D
ESIGN
F
LIGHT
I
NSTRUMENTS
SR20
7-20
P/N 11934-005
airspeed tape and denotes the current airspeed. Color coded bars are
provided to indicate flap operating range, normal operating range, caution
range, and never-exceed speed.
28 VDC for the MD302 Standby Attitude Module is supplied through the
5-amp STDBY ATTD A circuit breaker on ESS BUS 1 and the 5-amp
STDBY ATTD B circuit breaker on MAIN BUS 1.
Altimeter
Primary altitude data is provided by the Air Data Computer and is shown
as a vertical tape along the upper right side of the PFD. The altimeter scale
is graduated with major tick marks at intervals of 100 feet and minor tick
marks at intervals of 20 feet. Six hundred (600) feet of barometric altitude
is viewable at any time.
The local barometric pressure is set using the barometric adjustment knob
on the PFD. The selectable altitude reference bug is displayed on the altim-
eter tape and is set using the altitude selection knob on the Flight Manage-
ment System Keyboard. Barometric minimum descent altitude (MDA, or
Decision Height, DH), can be preset. Altimeter trend is also displayed as a
bar along side of the altimeter tape.
The PFD Altitude is corrected for static source position error (normal static
source / 0% flaps), the altitude calibration errors for the PFD are zero with
flaps up and normal source (typical cruise flight). Calibration corrections
are only necessary when flaps are extended or the alternate static source is
selected.
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.
Reissue A