Diamond Aircraft DV 20 E 2022, Airplane Maintenance Manual

Page: 478 / 903

AIRCRAFT
Indicating Systems
DV 20 E AMM
Page 4
15 Mar 2022
31-60-00
Doc # 4.02.25
Rev. 2
C. GDC 74A Air Data Computer (ADC)
The GDC 74A air data computer receives information from the pitot/static system and the GTP 59
outside air temperature (OAT) sensor. The GDC 74A is responsible for providing pressure altitude,
airspeed, vertical speed, and OAT information to the G500 system. The GDC 74A provides data
to the GDU 620 and GRS 77 using ARINC 429 digital interfaces. The GDC 74A also communicates
maintenance and configuration information to the GDU 620 using an RS-232 interface.
D. GMU 44 Magnetometer
The GMU 44 magnetometer senses magnetic field information. Data is sent to the GRS 77 AHRS
for processing to determine airplane magnetic heading. This unit receives power directly from the
GRS 77 and communicates with the GRS 77 using an RS-485 digital interface.
E. Databases
The GDU 620 utilizes the following databases:
)
Basemap Database.
)
Navigation Database.
)
Terrain and Airport Terrain Databases.
)
Obstacles Database.
)
IGRF (International Geomagnetic Reference Field) model.
With the exception of the Navigation database and IGRF model, which reside internal to the
GDU 620, all databases are stored on a single SD memory card that is inserted into the bottom slot
of the GDU 620. The following describe each database and how the databases are updated.
(1) Basemap Database
The basemap provides ground based references such as roads and bodies of water. The
database is stored in internal memory of the GDU 620 display. The basemap does not have a
scheduled update cycle and as such does not have an expiration date. The basemap database
is updated very infrequently.