Avidyne IFD540 Pilot's Manual page 200

The table below summarizes the databases update periods:
Database
Chart Data
Nav Data
Obstacle
Data
Terrain
Data
In the event the terrain data ever needs updating, this is also
performed through the front panel USB port.
Use one of the formatted fobs supplied by Avidyne (marked by
the Avidyne logo printed on one side). In the event you no longer
have those available, either call Avidyne for a replacement fob (a
nominal fee will be charged) or purchase a replacement through
other means. Acceptable alternative USB drives are FAT32
format, between 1-16 GB, and manufactured by WINTEC filemate
(http://www.wintecind.com/features/FileMate/USBFlashDrives.ht
ml).
To perform a data update, ensure the data to be updated is
placed onto one of the acceptable USB fobs. Carefully insert the
USB fob into the IFD USB slot while power is turned off. When
the IFD is powered up, select the "Setup" tab of the SYS page
and then pick the "Update Databases" LSK.
6-24 General
Update Cycle
14 days
28 days
56 days
As required
Comments & Source
Expiration watermark displayed
after 14 days indefinitely until
data updated (Jeppesen)
Airport, airway, navaid, airspace,
and FMS data (Jeppesen)
Displayed on map and used for
TA and FLTA functions
(Jeppesen)
Displayed on map and used for
TA and FLTA functions
(Jeppesen). The IFD is shipped
from the factory with this
database already loaded and
updates are anticipated to be a
rare occurrence.