BATTERY STARTING
The following diagrams represent the sequence of actions for a normal battery starting of the engines (steps 1 to 8 on the simplified schematic diagram). In this example engine no. 2 is started first.
Refer to AW139-RFM-4D – Section 2 for Normal Procedures.
STEP 1
Helicopter is parked and ready for flight. All switches are in the safe position.
STEPS 2 TO 3
When BATTERY MASTER switch is set to ON, Main and Aux Batteries are connected to ESS BUS 1 and ESS BUS 2 thus providing power to the rotorcraft essential loads.
The BATTERY MASTER switch at ON also enables the BATTERY MAIN and the BATTERY AUX switches.
When BATTERY MAIN switch is set to ON, the Main Battery is connected to MAIN BUS 1 (Main Battery contactor K3 closes) which is then also powered. When BATTERY AUX switch is set to ON, the Auxiliary Battery is connected to MAIN BUS 2 (Aux Battery contactor K4 closes), but MAIN BUS 2 is notpowered because of the reverse biased diode (CR5) which only permits recharging of the Auxiliary battery from MAIN BUS 2.
When GEN 1 and GEN 2 switches are set to ON they give an input to the relevant GCU so that the GCU will put the relevant generator on-line as soon as conditions permit.
23 VOLT CHECK
Before attempting starting the engine on batteries, the pilot has to check that the involved MAIN BUS voltage is not less than 23 V.
STEP 4
As in this example the engine no 2 is started first, the BUS TIE switch must be set to ON to power MAIN BUS 2.
BUS TIE Contactor closes thus connecting MAIN BUS 1 and MAIN BUS 2.