B744 tech questions

[main_dog]

Ok guys, please be gentle with a 742 driver about to embark on a 744 course...

Fuel question: if you depart with less than about 53T of fuel, my operator mandates a tank to engine departure, which on the 744 appears to be OVRDS 2 & 3 off, crossfeeds 1 & 4 closed and 2 & 3 open (as per FMSC logic).

My understanding, however, is that the FMSCs always close crossfeeds 2 & 3 automatically on selecting F10 or F20 after start, and do not open them again until cleaning up to F5 or less. If the FMSCs also do this in the tank to engine takeoff scenario, who is pressurizing the fuel manifold for takeoff? And does it matter?

What have I missed? :confused:

MD

[point8six]

That is the correct logic for tank-to-engine fuel panel set-up. Crossfeeds 2&3 are guarded switches and should not be touched in-flight, unless a checklist directs you to do so. Use your knowledge of the 742 to compare with the 744 systems - you will find much similarity, just a different presentation. Perhaps the most important difference is the FMA -learn it as quickly as you can and it will help with the "what is it doing now?" question! (the answer is, inevitably, exactly what you programmed it to do!). Good luck:ok:

[mustafagander]

doggy,
I can't stress enough that you MUST get a firm handle on Vnav. Learn what it will do and when, as well as what it will not do. In my outfit it seems that Vnav causes the most confusion.
As far as fuel panel set up goes, SOP will sort it and does it really matter what happens when flaps are extended to a take off position? With a tank to engine set up for T/O you won't be very heavy so 1 boost pump out is not a biggy.
BTW, I came to the B744 after 21 years on B747 classic. Never forget that the B744 is EICAS driven. Wait for a message with very few exceptions.

[main_dog]

Ok so in fact the crossfeed manifold is not pressurized during takeoff in this scenario...

Thanks for the advice guys :ok:; having been on glass before (albeit scarebus), I understand the importance of accepting it is an FMC/EICAS driven machine and that with a firm understanding of the "magic", all else will follow.

Having said that, I am still in a course-preparation phase, and was first going through the traditional systems to pick up similarities/ differences with the old lady before delving into Boeing's equivalent of FMS/ECAM!

So here's another system tech question... (but believe me when I start to study the FMC/FMA/EICAS I will have many more!)

If in flight with A/P R engaged I get an EICAS advisory >STAB TRIM 2, must I disengage the A/P (as you would have done on the 200)? By looking at the wiring diagrams, it would appear that in single-channel engagement A/P R can only utilize stab trim 2 (and similarly A/P L stab trim 3), but if this is the case why does our non-normal checklist not call for autopilot disengagement? :confused:

[point8six]

>stab trim 2 is an informational message -( there is a good write-up about use of the non-normal QRH in Checklist Introduction, Boeing QRH). A careted message requires no reference to the QRH as "the crew's action is obvious". It may well be transient, it certainly requires close monitoring and as a preference I would disengage R autopilot and engage either L or C autopilot.
The logic behind EICAS warnings and messages (including 'status messages') requires a thorough understanding, but don't try to "out-think" Boeing, as the a/c has now been in service over 20 years. Actions in the event of a malfunction, have been designed to simplify the operation, as much as possible, as there is no longer the 'luxury' of a Flight Engineer's knowledge.:{

[main_dog]

Thanks .86... I'll miss the F/Es as well, I suspect I'll spend much of the conversion course turning around only to find the sim instructor staring back... :{

Plus they knew all the good pubs!;)