737 Classic Battery Bus
 

According to www.b737mrg.net it's not possible to depower the Battery bus inflight by turning the battery switch off.

I can't find any info in the official manuals, and these days it's better not try in the real plane...

Pat, have I missed anything?

Thankyou, LEM

its true
 

According to and old manual page 10.20.08 oct 13/95
" The hot battery bus is always connected to the battery , there is no switch in this circuit . The battery must be above minimun voltage to operate units supplied by this bus. Hope it helps best regards edward

Lenstrand: there is a hot battery bus,a switched hot battery bus and a battery bus.You got it wrong with the hot battery bus.

Lem: turning the battery switch off will depower the switched hot battery bus,in any circumstances.
The battery bus will be depowered also,except when you select, on ground the Stby pwr switch to BAT,or inflight on AUTO or BAT positions. In this case ,the battery bus will be powered through the hot battery bus,thus powering the stby AC and DC busses. However the switched hot battery bus will be depowered.
Brgds....Alex

One question for you ,Lem, did you ever use the fuel measuring stick,if so,how? Where are the conversion,correction tables?

Hi Alex, you seem to confirm what Pat Boone says in his book: turning the battery switch off inflight (all the rest in normal configuration) will NOT depower the battery bus.

The Battery bus will continue to be powered by TR3, and the battery switch has no effect on this connection.

However, the Boeing system manual says:
"Battery (BAT) Switch
OFF-
. removes power from battery bus and switched hot batery bus when operating with normal powr sources available."
(...)

There is no mention about a difference between the on ground and inflight condition.

BTW, if I remember I'll try in the sim next week.



I used self-made measuring sticks every day in Zaire on my DC3 and similar airplanes, in my previous life, as all our gauges didn't work.
That was one of my favourite moments of the day, jumping on the wings, fuelling my airplane by myself, smelling the avgas in the middle of the immense and magnificent nowhere...
:{

But I presume you're asking about the 737 ;)
No, I've never used them.
That's a maintenance action, and if not in the AFM, the tables are in the Maintenence Manuals.
If that happens outstation, better have a company phone to hang on it!

LEM

Lem ,check also pg 6.10.5 regarding standby power switch.Says there that the battery bus is powered by the hot battery bus,regardless of the battery switch position,when switch is in BAT position.

wow,you flew DC3 in Zaire....That's life!!!....by the way,was this long ago?
A long way to the 737,I guess....I have some ideea,as I flew old,classic ,russian types planes, myself years ago..nice ,needles, aviation times....long way to the magenta line...

You mean "when the stby pwr switch is in bat position".
Yes, I know.
But that's not what I was asking for...
If you simply turn the battery switch off inflight, ALL THE REST NORMAL, will the battery bus be depowered?

Yeah... about 16 years ago... no gps yet, find the landing strip on compass alone, or die!

Don't make me think about that, I would give all gold in the world to buy a time machine and be sent back...:{ :{ :ugh: :ugh:

Also the old Antonov or Tupolev must have been great... when I fly to ex-ussr I feel somewhat like in Africa, the rough runways alone make me fall in love!
If it wasn't for the money, I would apply immediately!
And people are so nice, they've got a naive candor that doesn't exist anymore here... :(

,Lem.
Check pg 6.20.14 From this,I think that in order to have power on the battery bus,while inflight ,with stby pwr in AUTO ,you'll need to have the battery switch ON.
Otherwise,they would've said that battery switch can be on or off,like it's when you select stby pwr to BAT.
So,my guess,in normal configuration,select BAT to OFF-you'll be set for tea and biscuits with chief pilot...:cool: