Garmin G5 Installation Manual page 26

3.5.2.3 Performing an Electrical Load Analysis by Measurement
This section describes how to perform an electrical load analysis for a single alternator-single battery
electrical system. These procedures may be modified accordingly for aircraft with multiple batteries or
alternators, and it must be shown the maximum electrical demand does not typically exceed 80% of the
electrical system capacity.
In this section the following definitions are used:
normal operation: the primary electrical power generating system is operating normally.
emergency operation: the primary electrical power generating system is inoperative and a back-up
electrical power generating system is being used. This typically requires load shedding of non-essential
equipment to provide adequate electrical power to essential required equipment for safe flight and landing
of the airplane.
Either an in-circuit or clamp-on ammeter can be used for current measurement. The instrument used must
be calibrated and must be capable of reading current to the nearest 0.5 A, or better.
1. Record the continuous load rating for the alternator and battery.
2. Compile a list of electrical loads on the aircraft (generally, this is just a list of circuit breakers and
circuit breaker switches). See example in Figure 3-4 and Figure 3-5.
3. Identify whether each load is continuous (e.g. GPS) or intermittent (e.g. stall warning horn,
landing gear).
4. Using the worst-case flight condition, identify whether each load is used in a particular phase of
flight for normal operation. If some loads are mutually exclusive and will not be turned on
simultaneously (e.g. pitot heat and air conditioning), use only those loads for the worst-case
condition.
5. Identify whether each load is used in a particular phase of flight for emergency operation. As a
minimum, these systems generally include:
o COM Radio #1
o NAV Radio #1
o Transponder and associated altitude source
o Audio Panel
o Stall Warning System (if applicable)
o Pitot Heat
o Landing Light (switched on during landing only)
o Instrument Panel Dimming
6. Insert/attach the ammeter in the line from the external power source to the master relay circuit as
shown in Figure 3-1. This will eliminate errors due to the charging current drawn by the battery.
CAUTION
To avoid damage to equipment, ensure the ammeter is capable of handling the expected load.
Garmin G5 Electronic Flight Instrument Part 23 AML STC Installation Manual
Page 23 of 53
190-01112-10
Rev. 2