Manual Start on GE CF6

[Longhauler]

The DDG for our 744's with GE CF6's states that if the engines do not start after manual start procedures (assuming autostart is not available) then a modified manual start procedure may be used - set the STBY IGNITION switch to 1 or 2 then perform a manual start the usual way. The RR variant does not contain this option and I was wondering why?

As I understand it, on both variants the position of the AUTO IGNITION switch determines that the EEC alternates igniters for each engine start (or each second start for GE's) therefore if the intention is to force the EEC to use the other igniters then why can this method not be used on the RB211?

Regards,

LH

[spannersatcx]

We only use manual start as we don't have auto start.

Normal start procedure would be to select ign 1 or 2, if no light off after 30 secs then fuel to cut off motor for 30 secs then select AUTO IGN to BOTH not sure where STBY IGN comes into it for starting!

[Longhauler]

For a manual start, AUTO IGN is set to SINGLE which alternates between igniters 1 and 2 after every second ground start. STBY IGN is set to NORM which means the AC power system supplies power to the selected igniters (as determined by the position of the AUTO IGN switch). If the STBY IGN switch is set to either 1 or 2 then "..standby power system supplies power continuously to related igniter." I agree that setting AUTO IGN to BOTH would seem to be a more logical way to achieve this but I am simply relating the procedure we have in place.

I am theorising that this might be a way to overcome some sort of igniter-related problem to achieve a successful start but, as per my originial question, I don't see why this would not also be applicable to the RR Rb211's?

LH