747-400 Insulation Valves

[B-HKD]

Need some info regarding the 744.

Are Left ISLN and R ISLN switches ever used or does the queen do this automatically. I recently read this was part of engine start procedure, turn left off for starting 3-4 and right off for starting 1-2. Never seen this under the engine start in a 744 checklist and never heard of them being used.

Some insight would be great!

Leo:)

[SNS3Guppy]

Sure you don't mean isolation valves?

[B-HKD]

On the overhead of the 400 just under the pack switches to the left of pack 2 is the L ISLN isolation switch and to the right is the R ISLN switch. Thats what i mean. So what is their function? and are they really used during engine start and how?

Leo

[Sir Richard]

If there is LOW air pressure supplied by the APU or ground air sources,[for example at hot and high airfields such as Bogota or Mexico City], closing the offside ISLN valve can assist in maintaining air pressure for starting as there will be less opportunity for the air to leak away. (only one side of the air ducts will be perssurised) :8

[GlueBall]

Take this guy's B744 quiz: Boeing 747-400 Stuff - Flying the Boeing 747-400 (http://joanes.sy.googlepages.com/)

[BelArgUSA]

The correct name is "wing isolation valve" -
There is a L and a R wing isolation valve.
Would be nice to call things by their right name...
xxx
:*
Happy contrails

Also...
What is the "queen" in the original question...?
:suspect:

[tom744]

The isolation valve switches are used only it a bleed duct leak in L, C, or R duct occurs ( to isolate the leaking duct) or if a APU to pack take off has to be performed; the all 3 ducts are isolated, pack 1 and 3 off and pack 2 is supplied from the APU.
Source: Boeing QRH and OM vol.1, supplemaentary procedures.
P.S.: they are called "isolation valve switch" only, at least from Boeing, the manufacturer.

Cheers

[TopBunk]

BelArg

"Queen" = Queen of the Skies = B747-400.
xxx
Happy Contrails:)

[NOLAND3]

BelArgUSA - Wow Give the 16 year old kid a break..

And as the above poster stated if your operating outa somewhere like Quito, Bogota or very hot conditions you can perform a Pack to APU departure to give you a little extra margin, Packs 1 + 3 off and Isolation valves closed.

[BelArgUSA]

Glad I am retiring.
Blowing my fuse here with the XXIst century vocabulary.
Give this 64 old pilot a break too...
xxx
:(
Happy contrails

[warmkiter]

Hi you "insulation valve specialists" ;)


If a ground air start has to be performed because APU is INOP there is a nice "trick"

if you are in MEX or similar place where the air is thin and the GND air equipment is sometimes really weak the ducktpressure is too low. maybe only 9psi

Remember that the demandpumps 1 and 4 are running on bleed, so if you turn them off helps a lot. its like closing a big hole in the duckt...
etc. Starting engine 3 and switching Dem. Pum 1 off and R ISLN makes your ductpressure rise from 9 to 25
its not an official procedure but might make your day....

Lars

[Capt Fathom]

its not and official procedure but might make your day....

No further witnesses Your Honour, the Defence rests....

[B-HKD]

Thanks for the great answers guys! Makes perfect sence now.

BelArgUSA

No offense taken, i was simply convinced that the 747 would also be known as the "Queen" for those of you who are lucky enough to fly such a great plane :)

Cheers

[NSEU]

ducktpressure

Ducktpressure?

Remember that the demandpumps 1 and 4 are running on bleed, so if you turn them off helps a lot. its like closing a big hole in the duckt...
etc. Starting engine 3 and switching Dem. Pum 1 off and R ISLN makes your ductpressure rise from 9 to 25
its not an official procedure but might make your day....

Why are you running both demand pumps? Surely you should be running the #4 system on the electric AUX pump (or #1 and #4 AUX if you have two AUX pumps fitted).

Didn't realise these aircraft had such leaky ducts.

"Queen"... popularized by the Microsoft Flight Simulator community ;)

[B-HKD]

"Queen"... popularized by the Microsoft Flight Simulator community

Also popularized by some guys named Boeing

Known as the "Queen of the Skies," the 747 has carried 3.6 billion people more than 35 billion nautical miles (64.8 billion km) -- equivalent to 74,000 round trips to the Moon -- since entering service in 1970.

Boeing: Boeing 747, the "Queen of the Skies," Celebrates 35th Anniversary (http://www.boeing.com/news/releases/2004/q1/nr_040209g.html)

Leo :}

[Flight Detent]

Right on, B-HKD...

The 'queen' is the B747, not the B747-400!

[sengasengana]

Additionally:

For ground air start : only PART of the supplementary RR procedures :

Left ISLN Valve ............................................................ .............. CLOSE
Close Left Isolation valve to reduce duct leakage.
Duct pressure ............................................................ .............. OBSERVE
Observe duct pressure is minimum of 30 PSI (less 1 PSI per 1,000
feet of pressure altitude).
Autostart Switch ............................................................ ....................OFF
Engine No. 3 ............................................................ ....................START
Accomplish manual engine start etc...

On 744 there's usually plenty of ductpressure hot and high, if the APU runs normally, eg LTX: elev 9,200' ISA +20, our regular stop.

ss

[warmkiter]

to strawberry boy and NSEU

to my favorite strawberry type

if the APU is delivering "plenty of ducktpressure" you dont have to perform a ground air start. its performed when the APU does´nt deliver pressure :}

to NSEU

as we know the Demand pumps are AUX/ AUTO for engine start. 1,2 and 3 are AUTO and 4 is AUX

you asked why do i run the Demandpumps.its MAGIC! because the selector is in AUTO. It stands for AUTOMATIC:ok: .they run by them self. the conditions for demand pumps to jump in are

Respective Engine Driven Pump output pressure is low or respective Fuel Control Switch in CUTOFF

when hot and high and especially on ground air you are starting one engine at a time, its usually 2 or 3. ALL conditions are met for demand pump auto function. the number 1 demand pump runs magically by it self. this reduces "ductpressure":ok:

unless you turn number 1 demand pump selector to OFF instead of AUTO.:)

try it next time. if the APU is running normally, maybe the rise in PSI is not so significant, but if you are on a cart you will see the difference.

dont know if the FS2000 support this feature for the simmers:)

happy enginestarts

Lars

[sengasengana]

To w....r :

Quote : "to my favorite strawberry type

if the APU is delivering "plenty of ducktpressure" you dont have to perform a ground air start. its performed when the APU does´nt deliver pressure"

Never said groundair is to enhance ductpressure when APU in use, was the other bloke.

Secondly : check the spelling on my previous post and see where you go wrong...

Thirdly : B-HKD was only asking, when to twiddle with the knobs. Suggest you check who writes what...

ss