Instruction Manual

Instructions for Continued Airworthiness 190-01190-11 Rev. 1
for G500H in Robinson R44 Series Rotorcraft Page 9 of 20
Item Interval Description/Procedure
GDU 620, GRS 77H,
GDC 74H, GMU 44, GTP
59
Every 2200
flight hours or
twelve (12)
years,
whichever is
first
Perform an electrical bonding test for each listed LRU:
1. Gain access to the LRU (see General Arrangement
Drawing for LRU location)
2. Disconnect all harness connectors from the LRU
3. Measure the resistance between the LRU and a nearby
exposed portion of aircraft metallic structure. If any
resistances are greater than the values below refer to
section 3.5 of the Installation Manual, 190-01190-06 for
the bonding preparation and the maximum resistance
values that must be met.
a. For the GDU 620, verify the resistance is less than
or equal to 40 milliohms
b. For the GTP 59, verify the resistance is less than
or equal to 5 milliohms
c. For the remaining LRUs, verify the resistance is
less than or equal to 20 milliohms
4. Reconnect all disconnected harness connectors and
ensure they are secure
Repeat for each listed LRU.
2.6 Troubleshooting Information
If error indications are displayed on the GDU 620 display unit, consult the Troubleshooting section
contained below:
2.6.1 G500H Troubleshooting
Table 2-1. GDU 620 Troubleshooting Guide
Problem Cause Solution
Unit does not power up –
blank screen.
Improper wiring; circuit breaker
open.
Ensure power is properly wired to the
GDU 620 and the circuit breaker is closed.
Unit intensity turned down. Ensure that unit is not in manual intensity
control mode with the intensity turned
down.
All expected configuration
pages are not displayed.
An Installer Unlock Card is not
inserted into the GDU 620.
Insert the Installer Unlock Card
P/N 010-00769-60 into the bottom slot of
the GDU 620 and cycle power.
The GDC OAT probe type
shows up as UNKNOWN
The RS-232 connection to the
GDC 74H is not working.
Ensure that the GDC 74H RS-232
connection to the GDU is properly wired,
and ensure that the GDC 74H circuit
breaker is closed.
When loading software, the
LRU software is not being
displayed on the
SOFTWARE UPLOAD page.
The software loader card is
installed in the bottom slot of the
GDU 620.
Insert the loader card in the top slot and
cycle power to the GDU.
The software loader card contains
no information.
Repeat the process for making the
software loader card.
Configuration errors are
displayed on power-up,
before the GDU enters
normal mode.
The configuration module has not
been updated.
Update the configuration module.