AA.I.A.K7FAA-S-ACS-11A · Nov 2023Knowledge
Electrical system–alternators, generators, batteries, circuit breakers and protection d...
Electrical system–alternators, generators, batteries, circuit breakers and protection devices, controls, indicators, and external and auxiliary power sources and ratings.
Bottom line
Engine-driven alternators or generators supply electric current to the electrical system and maintain a sufficient charge in the battery. Most in-flight failures of the electrical system are located in the generator or alternator. It is essential that the pilot immediately shed non-essential loads when the generating source fails.
Key numbers
| Number | What it means |
|---|---|
| 5 amps per hour for 5 hours on a 25-amp hour battery | Battery life |
| only 2 hours at 10 amps on a 25-amp hour battery | Heavier load |
| about 10 or 15 minutes to full discharge at a 40-amp load | High load |
| electrolyte in a weak or discharged battery may freeze near 32° F | Battery freeze |
FAA references
- PHAK ch. 7 (p. 7-30) — FAA-H-8083-25C (2023)
- AFH ch. 18 (p. 18-13) — FAA-H-8083-3C
- SEA ch. 7 (p. 7-4) — FAA-H-8083-23
- AFH ch. 18 (pp. 18-9–18-10) — FAA-H-8083-3C
- RMH ch. 3 (p. 3-8) — FAA-H-8083-2A
- AC 91-78 ch. 20 , Electronic Aeronautical Chart Display. — AC No: 91-78A
- AC 91.21-1, para. 10.5 — AC No: 91.21-1D
- AC 120-76, para. 10.4 — AC No: 120-76D
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