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The power knob on the left side I could not remember is the left hand AC power feed.  Like I wrote you do want to rotate that to the on position once you have at least one generator on line and engine on speed.

BTW:  One other thing I forgot.  The GTC on the C-130E models (affectionately known at the Goat) cannot be on during flight because the doors cannot withstand the air pressures.  So, you must shut down the GTC and shut the doors prior to taxi.

The H models and later (including the MC-130E) had the APU which was a similar small turbine engine to produce bleed air and power but it had its own air intake on the right side of the aircraft and was rated for air operations.  So we could and did keep the APU powered up during flight.  It could provide an emergency source of power if for some strange reason all four engines had to be shut down in flight.

Ken

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Hope this helps.