Page 7-2
G900X/G950 Installation and Maintenance Manual – GRS 77 and GMU 44
Revision D
190-00719-00
1)
North of 65° North latitude between longitude 75° W and 120° W. (Northern Canada)
2)
South of 55° South latitude between longitude 120° E and 165° E. (Region south of Australia and
New Zealand)
Interface Summary
The following is an interface summary for the GRS 77 and GMU 44.
•
GMU 44 to GRS 77 Interface: Power, RS-232, RS-485 (19,200 baud)
•
ARINC 429 Input From GDC 74A Air Data Computer (low-speed)
•
2 ARINC 429 Outputs to GDU 1040 PFD/MFD (high-speed)
•
2 ARINC 429 Outputs to GIA 63W Integrated Avionics Units (high-speed)
•
2 RS-232 Inputs From GIA 63W Integrated Avionics Units (19,200 baud)
•
2 Aircraft Power Inputs
7.2 Electrical
Specifications
Table 7-1. GRS77/GMU 44 Electrical Specifications
Specification Characteristic
Power Requirements
Including GMU 44
Supply Voltage: 14/28 VDC. See the Environmental
Qualification Form* for details on surge ratings and
minimum/maximum operating voltages. See Table 1-3 for
current specifications.
*NOTE: As stated in Note 3 of the GRS 77 EQF (005-00165-31) the power inputs of the GRS 77 are
rated to sustain A4 (waveform 4 level 4 and waveform 3 level 4) if both are connected to a power input.
In the case of a single power source, where typically only one of the power pins would be used, both pins
should be connected to this wire to get A4. The splice must be in the backshell of the GRS 77. Generally
every installation should do this unless it is known that A3 on the power pins will suffice. Installations
that input 2 different power sources to the two power input pins will need to be examined on a case by
case basis.
7.3 Environmental
Specifications
Table 7-2 lists general environmental specifications. For detailed specifications, see the Environmental
Qualification Forms for the GRS 77 and the GMU 44.
Table 7-2. GRS77/GMU Environmental Specifications
Specification Characteristic
Regulatory Compliance
RTCA/DO-160D Environmental Conditions and
EUROCAE/ED-14D
Unit Software
RTCA/DO-178B Level B
Operating Temperature
Range
-55
°
C to +70
°
C
Altitude 55,000
Feet