STEMME S12, Maintenance Manual

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DOCUMENT NUMBER:
L500-912.820 ISSUE JUL 20, 2016
AMENDMENT: 00
DATE: --
CHAPTER- PAGE 3-37
MAINTENANCE MANUAL STEMME S12
3.7 ELECTRICAL SYSTEM
3.7.1 GENERAL SYSTEM ARCHITECTURE
The electrical system of the S12 consists of two independent, separate sub-systems: the main
system and the engine system. Each system incorporates a dedicated battery and generator
(actually an alternator and rectifier for the main system). Failures of one system will not interfere
the other system. There is no provision to cross-tie the two sub-systems.
The engine system powers exclusively those devices needed to operate the engine or which are
available only when the engine is running. Under normal conditions the engine system battery is
charged by the internal generator of the ROTAX engine. In gliding flight the engine system is shut
off completely. The operational mode of the engine battery is a stand-by mode, as it is normally
used only for engine starting. Under normal conditions it will not be discharged.
The main system powers all other devices of the aircraft. During powered flight its battery is
charged by the external belt driven alternator. During gliding flight the main system battery
powers all active devices. Once the main system battery is exhausted, the pilot is able to restart
the engine using the still fully charged engine system battery.
After successful restart of the engine, the external alternator will power the main system and will
recharge the main system battery. The operational mode of the main system battery is as a stor-
age battery in cycle mode. Under normal conditions it will be regularly discharged and recharged.