NG Start Valve Open NNC
 

Hi

First of all b737900 is barred from responding too this post. If he does I ll just ignore the person anyway.


The FCOM procedure on a normal start is after a successful start if the edge start switch does not go to Auto/OFF from GND then manually turn it to that position.

Why then is there a reference NNC for Start Valve Open which has the first item as Engine Start Switch Auto/OFF?

Is Boeing kind of contradicting itself here by telling us to move as part of the Engine start procedure and then to double check that action in the NNC?

Many thanks

Pin

What if you are on descent in rain and the start switch is in continuous?

What has 'Continuous' for the ignitors got to do with the Start Valve?

It's the same switch.

Rat, I was trying to get him/her to think of the situation unfolding airborne, it doesn't always happen during start. Boeing recognise that the switch may not always be in GND when this fault occurs so they are ensuring that the switch is where they want it before moving onto the next step......they want it in Auto/Off.

good call framer, didn't think about that.

any more people?

The only time I've seen it in real life ( apart from on every start) was in the cruise!

2 separate problems, one of which has a symptom that might look 'similar'

Engine start switch didn't move to auto/off. The switch is being restricted (not uncommon with age) from moving to the auto/off position, but otherwise, its no longer actually doing much (no other lights, etc).

Start valve open means there is a valve still open which should have closed. is it being commanded open? or is it stuck?

Pin Head how nice of you but for the record B737900 is not male ;)

As one of the other posters have said, Start valve open and Start switch not turning off are two separate issues.

The SW not turning to off is a solenoid issue with the physical switch, where the start valve is the butterfly valve in the engine.

Thank you everyone.