B737 Start Valve, Minimum Time Between 1 And 2...

[80/20]

Interesting discussion Ingo, lets compare notes – not win but to learn more – at least for me. Here are my sources:

Quickly: comes from Boeing Flight Operations Technical Bulletin 737-ALL 99-1, February 12, 1999 suggests minimum delay between starts.

"...you must monitor engine until stabilized..." Yes but this can be done while starting the last engine per FCOM Volume 1 NP 20.20 Engine start procedure: First Officer should monitor stabilization while Captain starts the last engine (Boeing training technique suggests that there is no need to wait for stabilization of the first engine before starting the last engine - all you need is start valve closed).

difference of Classic and NG
NG FCOM: START VALVE OPEN Alert:
Steady – respective engine start valve open and air is supplied to starter
NG MAINTENANCE MANUAL: The engine start valves send a ground discrete to the DEUs when the valve is in the open position.
CLASSIC FCOM: START VALVE OPEN Light is Illuminated (amber) – related engine start valve is open and air is being supplied to the starter. Don’t have a classic maintenance manual handy right here but I suspect it would say what you point out Ingo which might be different from the NG? In addition the calssic does not have blinking – for uncommanded opening of start valve.

The 200 is different again I think - B737-200 FCOM: The START VALVE OPEN light monitors air pressure downstream of the starter valve.

My conclusion – Boeing suggest that we keep a minimum delay between starts and this is further facilitated through 737NG FCOM Normal Amplified Procedures/Normal Checklist draft 4/29/2004