Electrical Load Analysis; Table 3-19 Lru Current Draw; Table 3-20 Net Electrical Load Change Calculation Example (14 Vdc Aircraft) - Garmin GI 275 Installation Manual

3.5 Electrical Load Analysis

An Electrical Load Analysis (ELA) must be completed before the GI 275 is installed to verify that the
aircraft electrical system is adequate. The purpose of the ELA is to show compliance with 14 CFR 23.1351
and 23.1353(h) by demonstrating that the maximum electrical system demand does not exceed 80% of the
alternator data plate rating and the aircraft battery is capable of providing electrical power to equipment
essential for continued safe flight and landing in the event of a complete loss of the primary electrical
system. Satisfactory completion of the ELA must be recorded on FAA Form 337.
NOTE
Certain operating requirements (e.g., 14 CFR Part 135) may impose additional requirements in
the event of electrical power loss. It is the installer's responsibility to ensure that the aircraft meets
the additional requirements if used for these operations.
Typical current draw of all GI 275 system components is summarized in Table 3-19.
LRU
GI 275 Base (without battery)
GI 275 Base (with battery)
GEA 24
GSB 15 Dual Type-A
(charging from both ports)
GSB 15 Type-A & C and Dual Type-C
(charging from both ports)
Net change to the electrical load with the GI 275 installed must be determined. Net decrease in electrical
load requires no further analysis, assuming that the electrical system is within limits. This is likely to occur
when existing equipment is removed or older systems are replaced with newer equipment that requires less
power to operate. The amended electrical load calculation documenting load reduction should be filed with
other aircraft permanent records. A sample net electrical load calculation is shown for a 14V aircraft in
Table 3-20.

Table 3-20 Net Electrical Load Change Calculation Example (14 VDC Aircraft)

Equipment Removed
Item
Mid-Continent MD 200-206 VOR/LOC/GS
Indicator
A complete Electrical Load Analysis must be performed to show adequate capacity of the alternator/
generator if the electrical load is increased with GI 275 installed. ASTM F 2490-05 Standard Guide for
Aircraft Electrical Load and Power Source Capacity Analysis offers guidance on preparing an ELA.
Alternatively, electrical loads under different operating conditions can be measured (refer to Section 3.5.1).
190-02246-14
Rev. 11

Table 3-19 LRU Current Draw

14V System
Typical
0.65 A
0.65 A
0.20 A
Varies
Varies
Load [A]
0.30 Garmin GI 275 Base
SUBTOTAL 0.30
Current Draw
Maximum Typical
0.75 A 0.32 A
1.70 A 0.32 A
0.40 A 0.10 A
2.86 A Varies
4.86 A Varies
Equipment Added
Item
NET CHANGE
GI 275 STC EIS & MFD Installation Manual
28V System
Maximum
0.40 A
0.80 A
0.20 A
1.43 A
2.43 A
Load [A]
0.75
SUBTOTAL 0.75
+0.45
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