2.5.2 Display Backlight
The display backlight lamp is rated by the manufacturer as having a usable life of 20,000 hours. This life
may be more or less than the rated time depending on the operating conditions of the 500W series unit.
Over time, the backlight lamp may dim and the display may not perform as well in direct sunlight
conditions. The user must determine by observation when the display brightness is not suitable for its
intended use. Contact the Garmin factory repair station when the backlight lamp requires service.
2.5.3 Battery Replacement
The 500W series has an internal keep-alive battery that will last about 10 years. The battery is used for
GPS system information. Regular planned replacement is not necessary. The 500W series will display a
'low battery' message when replacement is required. Once the low battery message is displayed, the
battery should be replaced within 1 to 2 months.
If the battery is not replaced and becomes totally discharged, the 500W series unit will remain fully
operational, but the GPS signal acquisition time may be increased. This acquisition time can be reduced
by entering a new seed position each time the unit is powered on. There is no loss of function or
accuracy of the 500W series unit with a dead battery.
The battery must be replaced by the Garmin factory repair station or factory authorized repair station.
2.5.4 Bonding Check (IFR-certified aircraft only)
Every 2000 flight hours or ten (10) years, whichever is first, perform an electrical bonding check on the
GNS 500W Series Unit and if installed, the Flight Stream 210. If a bonding check was not done during
the initial installation, it must be done to support electromagnetic interference and lightning compliance.
2.5.4.1 GNS 500W Series Unit in Metallic or Tube/Fabric Aircraft
Perform an electrical bonding check as follows:
1. Remove the 500W unit from the mounting rack.
2. Remove the backplate assembly from the rack.
3. Measure the resistance between the mounting rack and nearby exposed portion of aircraft
metallic structure and verify it is less than 10 milliohms.
In the event of bonding test failure, remove the 500W rack and clean the attachment points with a
bonding brush at both the 500W rack and the aircraft and reattach the rack to the rails in the panel.
Verify the resistance between the mounting rack and nearby exposed portion of aircraft metallic structure
is less than 2.5 milliohms.
4. Reinstall the backplate assembly and reinstall the 500W in the mounting rack.
2.5.4.2 GNS 500W Series Unit in Composite Aircraft
Perform an electrical bonding check as follows:
1. Remove the 500W unit from the mounting rack.
2. Remove the backplate assembly from the rack.
3. Measure the resistance between the mounting rack and the instrument panel, verify it is less
than 10 milliohms.
In the event of bonding test failure, remove the 500W rack and clean the attachment points with
a bonding brush at both the 500W rack and the aircraft and reattach the rack to the rails in the
panel. Verify the resistance between the mounting rack and the instrument panel is less than 5
milliohms.
4. Reinstall the backplate assembly and reinstall the 500W in the mounting rack.
500W Series
Instructions for Continued Airworthiness
190-00357-65 Rev. D
Page 6 of 12
Imprimer la page