Electrical Load Analysis; Figure 3-7 Gps/Sbas Antenna Minimum Ground Plane Radius; Aircraft Without Existing Electrical Load Analysis; Electrical Load Is Decreased After Modification - Garmin GTX 335 w GPS Installation Guidance

Figure 3-7 GPS/SBAS Antenna Minimum Ground Plane Radius

3.16 Electrical Load Analysis

NOTE
Circuits should be protected in accordance with the approved data in this document. Refer
to the guidelines in AC 43.13-1B, Chapter 11, Section 4 and to appendix B for
recommended circuit breaker ratings.
An electrical load analysis (ELA) must be completed on each aircraft prior to installation to make sure the
aircraft electrical system is capable of supporting the GTX. The purpose of the ELA is to show compliance
with 14 CFR 23.1351. As part of the installation it must be shown that the maximum electrical system
demand does not exceed 80% of the alternator data plate rating. Satisfactory completion of the ELA should
be recorded on FAA Form 337. For Commuter Category aircraft, an electrical load analysis that accounts
for the electrical loads applied to the electrical system in typical combinations and for probable durations is
required. There are several approaches that can be taken as given in this section. For each approach use the
GTX 335 current draw values listed in table 1-3.

3.16.1 Aircraft Without Existing Electrical Load Analysis

Prior to undertaking a complete ELA, the net change to the electrical load resulting from the GTX
installation should be found. The results of this analysis determine how to proceed. If there is a net
decrease in electrical load because of the installation of the GTX (i.e., removal of existing equipment), no
more electrical load analysis is required. If there is a net increase in electrical load because of the
installation of the GTX, proceed to section 3.16.3.

3.16.2 Electrical Load is Decreased After Modification

In instances when older systems are replaced with newer equipment, the electrical load presented to the
power system may be decreased. If the overall load on the electrical system is decreased because of the
GTX installation, no more analysis is required. This assumes that the electrical system was within all limits
prior to the GTX installation. The amended electrical load calculation should be added to the aircraft
permanent records to document the electrical load reduction.
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GPS
ANTENNA
GROUND PLANE
GTX 335 w/GPS Installation Guidance
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