Hi chaps,

 

Can I just ask why the PACKS.........OFF item on the secured normal electronic checklist in the PMDG 777 isn't a closed loop item, whereas the item is closed loop in the abnormal checklist during a pack failure/overheat? I'm sure there's some reason for  it  but I don't quite understand the difference.

 

Cheers!

The abnormal condition wants the packs kept off possibly to prevent damage to them, pack failure/overheat can be caused by something that a "reboot" is not going to fix.

But surely the secured checklist wants the packs kept off too, if the procedure is to have them shut down when securing the aircraft?

 

 

But surely the secured checklist wants the packs kept off too, if the procedure is to have them shut down when securing the aircraft?

 

You missed the point, sure they will be kept off normally; however, if for whatever reason you wanted to turn them on it is unlikely to break anything or start a fire so there is no reason to include the "do not do this" instruction.

I do get what you're saying Dan, but my question is why can the EICAS detect that the Pack switches have been turned off in an abnormal checklist, but it can't detect that the packs have been switched off in the normal Secured checklist?

If for some reason you don't want to switch the packs off, for example airline SOP, or its very hot on the ramp and you need to leave the packs running, then a manual check signifying the pack switches are as required is fine and means you don't have to override the checklist to complete it.

 

Without an air source the packs will be off after shutdown anyway. Switching them off makes sure that when air pressure is connected the packs don't run automatically. With an in flight failure there will be reasons why the pack must be switched off.

I understand now Kevin. Thanks for that.

By the way, if it were SOP to keep the packs running, could an airline in the real aircraft customise the pack item to make it automatic/closed loop in the Secured checklist? Am I right in thinking that the checklists in the real aircraft can be tailored to company requirements? Or could they, for example, tailor it to have an 'As Required' rather than 'Off' response on the electronic checklist? This is just an aside - I understand the answer to my first question now.

I understand now Kevin. Thanks for that.

By the way, if it were SOP to keep the packs running, could an airline in the real aircraft customise the pack item to make it automatic/closed loop in the Secured checklist? Am I right in thinking that the checklists in the real aircraft can be tailored to company requirements? Or could they, for example, tailor it to have an 'As Required' rather than 'Off' response on the electronic checklist? This is just an aside - I understand the answer to my first question now.

I don't know for sure, I was just giving reasons why it might not be a closed loop check in this case. However FCOM 1 provides a clue in Supplementary Procedures, page SP.16.15.

 

Do the normal Secure Procedure with the following modifications:

 

If the airplane will be attended

 

PACK Switches.......................AUTO    F/O

 

So there are occasions where the check is changed.