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Engine Starting Cycle


munirabbasi
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Depends... On your model aircraft, starting air source as well as definition of "ALL" electrical power loss meaning AC and DC and at what point RPM the power loss occurred.

If you have Engine Bleed Air Regulator valves they will close (Spring loaded closed when de-energized) and your starter control valve is also spring loaded closed when de-energized. If you have an APU the solenoid fuel valve will be de-energize closed resulting in loss of air so if the power loss occurred prior to 50% or so the engine would stall and overtemp without engine instrument indications.

In "older" aircraft NATOPS has a CAUTION about loss of the GTC during start (first engine) requiring the condition lever be placed in feather in case of loss of power "opening of the Battery Relay" as no power would be available to close the fuel control shutoff valve. 

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15 hours ago, NATOPS1 said:

Depends... On your model aircraft, starting air source as well as definition of "ALL" electrical power loss meaning AC and DC and at what point RPM the power loss occurred.

If you have Engine Bleed Air Regulator valves they will close (Spring loaded closed when de-energized) and your starter control valve is also spring loaded closed when de-energized. If you have an APU the solenoid fuel valve will be de-energize closed resulting in loss of air so if the power loss occurred prior to 50% or so the engine would stall and overtemp without engine instrument indications.

In "older" aircraft NATOPS has a CAUTION about loss of the GTC during start (first engine) requiring the condition lever be placed i n feather in case of loss of power "opening of the Battery Relay" as no power would be available to close the fuel control shutoff valve. 

I remember using "hot day start" on A models when starting engines without external power applied and losing the ATM.All GTC bleed air went toward spinning #3 up to starter cut out speed.A little scary the first time it happened to you and more so if it happened at night.A flashlight handy was a must! If the engine start check list was adhered to and #3 generators were selected on, as soon #3 was on speed,the lights came on and you could start breathing again.    

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We had GTC and ATM on the earlier aircraft and yes we too "Took the ATM and Gen OFF line" during start to give the air to the starter. You would loose the AC power but the DC power remained so there was no issue with the start and the secondary AC provided engine Insts.   

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