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ENGINE START


Bison501
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Give me the old C-118 days. Only time pilot touched any engine controls was during taxi. FE started engines and handled all throttle and mixture controls all the other times. I've been known to "manipulate" the throttles a time or 2 on the Herc, as well as the flap and gear handles when needed.

What were you useing to reach the gear handel from the engineers seat George? Was the crew chief holding on to your shoulders as you leaned foreward or were you holding down the C/P seat?

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Wasn't or isn't the red light in the starter button turned on by the starter control valve opening?

The light illuminating signals that the start interlock relay is energized. The relay will not energize unless several conditions are met, such as the fire handle being in, the oil tank s/o/v being open, etc. The starter comtrol valve opens if the interlock relay is energized, and if you have bleed air applied to the motor.

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The "red button" light on the old aircraft when illuminated only indicates the start control CB is "IN"... With NO Bleed air to the starter control valve and the button pushed in the light should illuminate with no rotation... add air, valve opens, prop rotates...

If the oil CB was pulled for a oil drain down" condition you could try to "start the engine" it would rotate (and light off) but you would get NO oil pressure and Stop Start at 35%...

So a mod was done that prevented the start control valve from opening (prevent rotation without oil pressure) if the oil CB was out or the interlock relay was bad...

Newer aircraft with the start valve open light.... The start valve open light is a pressure switch downstream of the start control valve and indicates the valve is open (or not closed).

The earlier mod remained (prevent rotation without oil pressure) so we teach "press to test" the light prior to the start switch movement so you know the Start CB, Oil CB and the interlock relay are all good.

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The light illuminating signals that the start interlock relay is energized. The relay will not energize unless several conditions are met, such as the fire handle being in, the oil tank s/o/v being open, etc. The starter comtrol valve opens if the interlock relay is energized, and if you have bleed air applied to the motor.

Correction...the fire handle needs to be in, yes, but the system has no idea if the oil shut off valve is open, only that the CB is closed. I know it's abit nit-noid, but the assumption that the oil valve has to be open if you got the light could be bad in the wrong circumstance.

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Well come on now... if the fire handle is in and the oil CB is in I ASSUME the oil valve is open...

As you staed there is NO correlation between the "red light" and the oil valve "being open"....

Thats why we look for oil pressure at 35%

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Correction...the fire handle needs to be in, yes, but the system has no idea if the oil shut off valve is open, only that the CB is closed. I know it's abit nit-noid, but the assumption that the oil valve has to be open if you got the light could be bad in the wrong circumstance.

If you look at the wiring diagram in 1C-130H-2-70FI-00-1-1, Figure 2-14, pg 2-465, you will see that the start interlock relay is in the circuit for the open side of the oil tank shutoff valve. The oil shutoff C/B only provides power to the system.

And yes, if the oil shutoff valve is not full open, even so much as a crack, the start interlock relay will still engauge, making you start an engine with inadequate oil pressure. Had it happen. That's why the T.O. used to say visually verify the shutoff valve before some dummy changed the T.O. to say an audio check is good enough.

Only flight crew is allowed to "assume" the oil valve is open, because, good luck visually verifying it while in flight.

There are also plenty of reasons to check for positive oil pressure at 35%, such as failure of the oil pump or ADH, a ruptured line, a failed pressure regulating valve, etc.

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