Specifications

Information Manual 7-31
Cirrus Design Section 7
SR20 Airplane Description
Horizontal Situation Indicator
• Note •
Serials 1337 and subsequent: The Horizontal Situation
Indicator is integrated into the PFD.
Avionics Configuration 2.1:
The Century NSD-1000 is a conventional HSI that provides gyro
stabilized, magnetically slaved, heading information, a pictorial VOR/
LOC display with a conventional course arrow, and glideslope
presentation. The instrument displays airplane heading by rotating a
compass dial in relation to a fixed simulated airplane image and lubber
line. The HSI directional gyro, which drives the compass dial, is slaved
to a flux detector in the right wing through an amplifier under the
copilot’s floor. A FREE GYRO–SLAVE switch, below the display,
allows the pilot to select either Free Gyro mode or Slave mode. In
Slave mode, the gyro is slaved to the flux detector. In Free Gyro mode,
the gyro must be manually set to the airplane’s magnetic compass
using the PUSH-SET-CARD knob in the lower right corner of the
instrument. The course is set using the Course (Arrow) knob in the
lower left corner of the instrument. The HSI course and heading
outputs provided to the autopilot to allow NAV/LOC/GPS course
tracking or to track a preset heading.
The HSI incorporates conventional warning flags. The HDG (Heading)
flag will be out of view whenever the instrument is receiving sufficient
electrical power for operation. The NAV (Navigation) flag will be out of
view when a VOR or LOC frequency is tuned in the NAV1 receiver and
a reliable signal is present. The GS (Glideslope) flag will be out of view
when an ILS frequency is tuned on the Nav 1 receiver and a reliable
GS signal is present.
The NSD-1000 HSI is electrically driven and a red GYRO flag
indicates loss of electrical power. Redundant circuits paralleled
through diodes at the indicator supply DC electrical power for gyro
operation. 28 VDC for the redundant power circuits is supplied through
the 5-amp HSI/PFD 1 circuit breaker on the Essential Bus and 5-amp
HSI/PFD 2 circuit breaker on Main Bus 2.
March 2010