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-   -   747 Classic question (https://www.pprune.org/tech-log/622656-747-classic-question.html)

Oyster Shucker 19th Jun 2019 09:47

747 Classic question
 
I never flew the classic, so I have no clue. Saw this on fb:

“On long range sectors, where fuel could be critical, and dodgy weather they (a kangaroo airline) would fly single pac, the air became very stuffy, it was hard to breathe when working, a quick visit to the flight deck confirmed it, only one pac running, they weren't supposed to do it, but they did.”

Could it fly with one pack ops?






mustafagander 19th Jun 2019 10:34

Nope.
For the B747-300 I think there was a "half flow" option on the pack controllers for use in crz. SOP's mandated what pack selection was used and 1 pack was not one of them. Personally I, FEO, only ever used half pack on the Capt direct instructions coz it saved 3/5 of 5/8 of FA fuel. The possible fuel savings disappeared in the static like heavy airframes - OJU was heavy and always had difficulties BKK-FCO while other aircraft made it OK.

Oyster Shucker 19th Jun 2019 10:42


Originally Posted by mustafagander (Post 10497534)
Nope.
For the B747-300 I think there was a "half flow" option on the pack controllers for use in crz. SOP's mandated what pack selection was used and 1 pack was not one of them. Personally I, FEO, only ever used half pack on the Capt direct instructions coz it saved 3/5 of 5/8 of FA fuel. The possible fuel savings disappeared in the static like heavy airframes - OJU was heavy and always had difficulties BKK-FCO while other aircraft made it OK.

Yeah. I would have thought that a single pack ops would affect ventilation, pressurisation and equipment cooling?

Is half pack similar to low flow on the -400? and was that with 3 or 2 packs ON?

cheers

Private jet 19th Jun 2019 10:48

Some airlines had an SOP to switch off ONE pack in the cruise ( so 2 packs still running) to reduce fuel burn, in theory, by a small percentage.
Yes, the -300's had a half pack setting as well & low flow on -400. Personally I thought the air on a highly populated 747 was never great in terms of quality or quantity even with 3 packs running.

Oyster Shucker 19th Jun 2019 10:58

from b747classic.co.uk

One Pack Operation:
Galley / Lavatory exhaust fan Auto / On
Recirculating fans On
Gasper fan On

Supplemental vent fans On”


Is 1 pack ops possible?

ScepticalOptomist 19th Jun 2019 11:06

On the 747-400 we used to have cabin crew ring up / visit the flight deck and ask for more oxygen.. They would not believe that we had no such control.. I’d take the original post with the required pinch of salt... :rolleyes:

stilton 20th Jun 2019 01:44

In the account of the Qantas 744 that flew non stop from London to Sydney many different fuel saving techniques were used


One of them was to use only one pack for
the entire journey, towards the end of which
they were at FL450


Of course I don’t think they had any more than 20 people on board including pax and crew


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