Electrical starting equipment
The electrical equipment for the starting includes: an electrical starting motor, a motor pump for the feeding of the ignition torches, a solenoid valve and spark plug of high voltage in each one of the two ignition torches.
A ground equipment is used for the starting and the circuit employed is duplicated for each engine. The equipment of the airplane includes: a starting panel, two voltage elevating coils and the pumps of the fuel tank, with the necessary switches.


Starting Cycle
With the master starting switch, switch of the pump of the fuel tank and the ignition switch closed, the electrical circuits for current feeding of the fuel tank pump and the starting panel are completed. The alarm light of fuel pressure is ignited until it has been managed to accumulate an advisable pressure in the low pressure fuel system. With the accelerator in the closed position, the oppression of the starting button completes the circuit to the electromagnetic motor that extends the main spiral spring of an incorporated time release mechanism in the starting panel.
As soon as the starting button is released, the chord mechanism of escape is put in movement under the action of the spiral spring, turning the cams that control the three pairs of contacts.
The first movement of the cams closes the contacts "A", completing the circuit to the main magnetic relay, which simultaneously gives energy to the starter engine, voltage elevating coils, ignition torches' solenoid valves and to the ignition torches' feeding pump relay and its motor. At the same time, contacts "B" are opened which assures that a new press of the starting button will not have effect until the starting cycle of 30 seconds is complete. The starter engine gears up without some abruptness since a reduced voltage is provided to him due to the clutch resistance that is in circuit during this stage.
After 1 to 3,5 seconds, contacts "C" are closed and the second magnetic relay is energy loaded. This puts in short circuit the clutch resistance and applies the complete voltage to the starter engine.
When finalizing 30 seconds from the beginning of the starting cycle, the contacts "A" and "C" that control the magnetic relays open, disconnecting therefore the current feeding to the starter, voltage elevating coils, ignition torches etc., and at the same time, contacts "B" are closed in preparation for the next start cycle.