4.1 To show compliance with 14 CFR 23.1351, you must determine the electrical system capacity.

4.2 14 CFR 23.1351(a)(2) states that:

4.2.1 For normal, utility, and acrobatic category airplanes, by an electrical load analysis or by electrical measurements that account for the electrical loads applied to the electrical system in probable combinations and for probable durations; and

4.2.2 For commuter category airplanes, by an electrical load analysis that accounts for the electrical loads applied to the electrical system in probable combinations and for probable durations.

4.3 The primary purpose of the electrical load analysis (ELA) is to determine electrical system capacity (including generating sources, converters, contactors, bus bars, and so forth) needed to supply the worst-case combinations of electrical loads. This is achieved by evaluating the average demand and maximum demands under all applicable flight conditions. A summary can then be used to relate the ELA to the system capacity and can establish the adequacy of the power sources under normal, abnormal, and emergency conditions.

Note 1-The ELA should be maintained throughout the life of the aircraft to record changes to the electrical system, which may add or remove electrical loads to the system.

4.4 The ELA that is produced for aircraft-type certification should be used as the baseline document for any subsequent changes. When possible, the basic format of the original ELA should be followed to ensure consistency in the methodology and approach.

4.5 The original ELA may be lacking in certain information, for instance, time available on emergency battery. It may be necessary to update the ELA using the guidance material contained in this guide.