§29.1165 Engine ignition systems

(a) Each bat tery i gnition sy stem must be supplemented wi th a generat or that is automatically available as an alternate source of electrical energy to a llow cont inued engine operation if any battery becomes depleted. (b) The capacity of bat teries and generat ors must be l arge enough t o m eet t he simultaneous demands of t he engi ne i gnition sy stem and the greatest dem ands of any electrical system components that draw from the same source. (c) The desi gn of t he engi ne i gnition sy stem must account for: (1) The condition of an i noperative generator; (2) The co ndition o f a co mpletely depleted bat tery wi th t he generat or running at its normal operating speed; and (3) The co ndition o f a co mpletely depleted battery with the generator operating at idling speed, if there is only one battery. (d) Magneto ground wi ring (for separat e ignition circuits) that lies on the engine side of any firewall must be installed, located, or protected, to minimise th e p robability o f th e sim ultaneous failure of two or m ore wires as a result of mechanical damage, electrical fault or other cause. (e) No ground wire for any engi ne m ay be routed t hrough a fi re zone of another engine unless each part of that wire within that zone is fireproof. (f) Each ignition system must be independent of any electrical circuit that is not used for assisting, controlling, or analysing the operation of that system. (g) There must be means to warn appropriate crew members if the malfunctioning of any part of the electrical sy stem i s causi ng t he cont inuous discharge of any bat tery necessary for engi ne ignition.