Bleed Air Cleaner

[TRAVENGINEER]

FOUND OUT AN OPTION ON THE 744 , IT IS A BLEED AIR CLEANER. SAUDI IS THE ONLY AIRLINE TO PURCHASE IT (I THINK).
IT REMOVES PARTICULATES FROM THE AIR AFTER PASSING THROUGH THE ENG INTAKE BUT PRIOR TO REACHING THE A/C PACKS. A CENTRIFUGE EXTRACTS THE PARTICULATES OUT OF THE AIR AND THEN DUMPS THE BY PRODUCTS OUT A DOOR. DOOR IS ACTIVATED AT 6000FT TO OPEN (BAROMETRIC SWITCH) WHEN THE SWITCH IS IN THE AUTO POSITION. IN THE OFF POSITION THE AUTO FUNCTION OF THE DOOR IS DEACTIVATED. THE SWITCH IS LOCATED ON THE P5 ECS PANEL.

MY QUESTION IS DOES ANYONE KNOW OF THE SYSTEM AND WHERE DOES THE CENTRIFUGE UNIT LIVE AND WHERE IS THE DOOR LOCATED AND HOW MANY UNITS ARE INSTALLED ON THE A/C.

THANKS.

[fruitloop]

Hiya travengineer,
Air cleaners arn't new,(although the system fitted to the 744 sounds like a potential headache,imagine trying to check its servicability on the ground;) )737/200 had them !!and I think that they were fitted to a few other early A/C. DC9,727/100 to name a few.

Cheers

[Flight Detent]

Hi all,
I understand the water seperators also do a fairly good job of cleaning the air as passes through, it's the main cause of problems with aircon temperature control on Boeings.

The seperators get dirty, generate a differential pressure each side in the duct, and the aircon system sees it as an ice build-up, and programs an increase in airtemp to get rid of it.
Usually have to go to manual mode to get control back, but have to be really careful not to freeze the seperators, because there is most always some ice in there!

Cheers

[fruitloop]

Flight Detent,
Yep !!you are correct that the water seperators 'help' clean the air and try to maintain between 32 and 37 degrees "F" (depending on spec,model) with help from hot air "anti-ice valving".However they have a massive by-pass capability so don't really act as a 'dedicated'air cleaner.Early 737's had a dedicated cleaner (for engines only)that had a constant 'bleed'overboard (hot air)so didn't suffer from freezing.

[Flight Detent]

Hi Fruitloop,
I don't entirely agree with that comment regarding bypass of water seperators, I don't remember any bypass at all!

But that was a long while ago!

Anyway, hows Brisbane, wish I was there now, should be going home again soon, live up north side, near Caloundra.

Cheers

[fruitloop]

High flight detent.
The weather here to-day was BEAUTIFUL (bound to get a bite).I actually live north-west of Brizzy At an altitude of nearly 600 feet(above the humidity boundry)and on a clear day can see Caloundra. Anyway with regards water separators (fitted to Boeings Fokkers )the bypass isn't external,that is it's built-in.When you look down the front of one you will see a pointed area.reach in and push it (less than 4 psi to move it from memory,different pressures for different models but they all do the same)otherwise if the seperator 'froze'up you would have no air at all.The temp probe for the control of 'anti-ice is generaly near the drain(incidently feed back onto the heat exchangers)so will begin to modulate prior to freezing"in theory"
A common prob experienced by crew is "thumping"in regards to airflow from packs.A lot of the time a water sep change cures it but not always !!!:)
Cheers