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readytotaxi
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Changing Cabin Filters, How Often?

Sat Oct 13, 2007 6:28 pm

Is there any FAA/CAA requirement to change the cabin air filters after so many trips or can airlines change these at routine maintenance when THEY think fit?
you don't get a second chance to make a first impression!
 
fr8mech
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RE: Changing Cabin Filters, How Often?

Sat Oct 13, 2007 7:11 pm

Cabin air filters???

You know, I've been in cargo aircraft for 17 years, but did work 3 years in pax operation and some side work with pax operators (in maintenance) and the only filters I have ever changed/cleaned (in chapter 21) are the temperature sensor filters (little foam pads) and the equipment cooling system filters (big, flow through, box filters). I've never seen a cabin air filter.

Not really required though. The air inside the cabin changes over several times during a flight. The amount of times has gotten smaller as technology and the need for efficiency has grown. I saw a chart once, maybe in a Boeing magazine.

Some newer jets may have them. I don't know.

If they were installed, they would be cleaned/replaced at manufacturer intervals during some sort of segmented check.
When seconds count...the police are minutes away.
 
tdscanuck
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RE: Changing Cabin Filters, How Often?

Sat Oct 13, 2007 7:55 pm

Quoting Readytotaxi (Thread starter):
Is there any FAA/CAA requirement to change the cabin air filters after so many trips or can airlines change these at routine maintenance when THEY think fit?

If the airplane had a filter, it's extremely unlikely that the FAA/CAA would set a change interval. The airline's maintenance plan is part of their operating certificate, which would include such an interval. The FAA/CAA can approve or deny the maintenance plan, and they have to make sure that the airline sticks to whatever they've agreed to, but the FAA/CAA don't directly dictate maintenance intervals except in a few rare safety critical cases.

Quoting Fr8mech (Reply 1):
Some newer jets may have them. I don't know.

787 supposedly will have HEPA filters.

Tom.
 
Tristarsteve
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RE: Changing Cabin Filters, How Often?

Sat Oct 13, 2007 10:11 pm

Quoting Fr8mech (Reply 1):
Some newer jets may have them. I don't know.

All aircraft with recirculation fans have cabin air filters. They are fitted to B757 B767 B777 B744 for sure.
They are changed very regularly as they are a fine mesh filter. If you don't change them they easily get blocked.
I would expect every 3 months is about right.
 
fr8mech
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RE: Changing Cabin Filters, How Often?

Sun Oct 14, 2007 12:43 am

Quoting Tristarsteve (Reply 3):
They are fitted to B757 B767

I haven't changed a recirc fan on a pax B757/767 in over 17 years, but I don't recall a filter attached to them.
When seconds count...the police are minutes away.
 
EMBQA
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RE: Changing Cabin Filters, How Often?

Sun Oct 14, 2007 1:18 am

Quoting Fr8mech (Reply 1):
Cabin air filters???

What cabin air filters....???

Actually I've worked on two planes that did have them... the Saab 340 and they were time changed. It had 3 total.... 2 for the pax cabin, one for the flight deck. The E-Jet has two that look like big shop vac filters

[Edited 2007-10-13 18:20:39]
"It's not the size of the dog in the fight, but the size of the fight in the dog"
 
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HAWK21M
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RE: Changing Cabin Filters, How Often?

Sun Oct 14, 2007 10:38 am

Quoting Tristarsteve (Reply 3):
All aircraft with recirculation fans have cabin air filters

True.

Quoting Fr8Mech (Reply 4):
I haven't changed a recirc fan on a pax B757/767 in over 17 years, but I don't recall a filter attached to them

Its attached to the line routed to the Recirculation fan & not directly to it.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
fr8mech
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RE: Changing Cabin Filters, How Often?

Sun Oct 14, 2007 4:39 pm

Quoting HAWK21M (Reply 6):
Its attached to the line routed to the Recirculation fan & not directly to it.

I'll need to dig in the paperwork. I assume the cargo version also has a filter in the duct work. Don't remember seeing a task to replace one though.
When seconds count...the police are minutes away.
 
Dalmd88
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RE: Changing Cabin Filters, How Often?

Sun Oct 14, 2007 10:48 pm

During our 757 Service Check cycle there are cabin recirc filter changes. It isn't on every one I think it is every other or third check in the cycle. I've never done one so I can't recall the location. I know on the MD88 there is one right next to the recirc fan aft of the C3 bulkhead. I know that doesn't get changed on our Service Check cycle. I'm thinking it is done on Letter Check when more stuff gets opened.

Air quality on airplanes is actually better than most homes and office environments when the packs are running. The air is changed very rapidly and tends to flow directly from the ceiling to the floor. There is very little movement from row to row.
 
saintsman
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RE: Changing Cabin Filters, How Often?

Mon Oct 15, 2007 7:17 am

I never had to change them, but I remember in the smoking days recirc fans being gummed up with nicotine. Nobody liked changing them.
 
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HAWK21M
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RE: Changing Cabin Filters, How Often?

Mon Oct 15, 2007 9:56 am

Quoting Fr8Mech (Reply 7):
I assume the cargo version also has a filter in the duct work

The Freighter has only one Recirculation fan for obvious reasons  Smile
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tod
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RE: Changing Cabin Filters, How Often?

Mon Oct 15, 2007 2:51 pm

Quoting HAWK21M (Reply 10):
The Freighter has only one Recirculation fan for obvious reasons

The 747 and 767 freighter conversions that I have worked on have had the recirc/supplemental air fans and filters removed.

The 747 gasper system has its own set of filters.

777 also have filters on the galley inlets for the lav/galley vent system.

Boeing has published a list of recommend HEPA filters for:
737-300/-400/-500/-600/-700/-800/-900
747-100/-200/-300/-400
757-200/-300
767-200/-300
777-200/-300
DC-10
MD-11
MD-80
MD-90

Tod
 
SFOMB67
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RE: Changing Cabin Filters, How Often?

Tue Oct 16, 2007 4:43 am

Pretty sure we used to replace the recirc filters on 767 at C-Cks. I also recall they went to a new charcoal or hepa filter, but that was 14 years ago.
Not as easy as originally perceived
 
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HAWK21M
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RE: Changing Cabin Filters, How Often?

Tue Oct 16, 2007 9:24 am

Quoting Tod (Reply 11):
The 747 and 767 freighter conversions that I have worked on have had the recirc/supplemental air fans and filters removed.

I was qouting on the B757 as the previous post  Smile
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
fr8mech
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RE: Changing Cabin Filters, How Often?

Thu Oct 18, 2007 8:18 am

Near as I can tell, from the AMM's, none of our B757/767/744, MD11 cargo aircraft we work have cabin air filters.
When seconds count...the police are minutes away.
 
b78710
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RE: Changing Cabin Filters, How Often?

Thu Oct 18, 2007 8:56 am

changed a recirc fan filter on a 343 on the line once, cant remember why, not the most pleasant of jobs!

Quoting Fr8mech (Reply 1):
he only filters I have ever changed/cleaned (in chapter 21) are the temperature sensor filters

we've been doing these on the line quite a lot lately, i think theyre meant to be done on a check, but the blokes in the hangar dont bother or something!

had it about 3 times in the last 5 weeks written up in the log "temp excessivly hot/cold in such n such an area"

check the temp sensor filters around the area and theyre full of shit!
 
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readytotaxi
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RE: Changing Cabin Filters, How Often?

Thu Oct 18, 2007 4:53 pm

Thank you everyone for the info, very helpful.
you don't get a second chance to make a first impression!
 
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HAWK21M
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RE: Changing Cabin Filters, How Often?

Fri Oct 19, 2007 12:29 pm

Quoting Fr8Mech (Reply 14):
Near as I can tell, from the AMM's, none of our B757/767/744, MD11 cargo aircraft we work have cabin air filters

Not on the B757s too.Im surprised.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
troubleshooter
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RE: Changing Cabin Filters, How Often?

Fri Oct 19, 2007 7:30 pm

I´ve had to replace both recirculation filters on an A319 last week. I don´t know the interval but I hope some time will go by until I have to do that again! Full face protection is required unless one is interested to breathe the dirt and viruses of thousands of passengers.

On the A320 family, these filters are installed shortly upstream of the recirculation fans. Access is through the fwd cargo compartment rear linings.
This job sucks!!! I love this job!!!
 
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HAWK21M
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RE: Changing Cabin Filters, How Often?

Sun Oct 21, 2007 8:45 pm


B764 Recirculation fan.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Fly2HMO
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RE: Changing Cabin Filters, How Often?

Mon Oct 22, 2007 1:50 am

Quoting HAWK21M (Reply 19):
B764 Recirculation fan.

Hmm, I wonder how much thrust it makes? Big grin
 
Dalmd88
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RE: Changing Cabin Filters, How Often?

Mon Oct 22, 2007 1:38 pm

It isn't the thrust that will get you. The torque on that sucker is a killer. We were warned about this in 767 school. Some mechanics have plugged a new fan in without mounting it to the airplane, 'just to make sure the problem isn't the aircraft wiring.' Allegedlly the fan will flail around pounding stupid mechanic in the process.
 
Tod
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RE: Changing Cabin Filters, How Often?

Mon Oct 22, 2007 2:30 pm

Quoting FLY2HMO (Reply 20):
Hmm, I wonder how much thrust it makes?

Free-wheeling this guy (Hamilton Sundstrand p/n 4100149) puffs along at about 1900cfm.

Fully loaded up with a dressure drop around 26 inches of water it still blows about 1000 cfm, drawing 12kw of power.

You wouldn't want to bench test this one sitting in your lap.  Wow!

Tod
 
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HAWK21M
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RE: Changing Cabin Filters, How Often?

Tue Oct 23, 2007 8:18 am


The B737 Gasper fan.
11,500RPM.Approx 5 kgs.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tod
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RE: Changing Cabin Filters, How Often?

Tue Oct 23, 2007 1:39 pm

Quoting HAWK21M (Reply 23):
The B737 Gasper fan

. . . and the rest of the Sundstrand catalog  Wink

http://www.hs-powersystems.com/prodindex.htm

Tod
 
FlyASAGuy2005
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RE: Changing Cabin Filters, How Often?

Tue Oct 23, 2007 4:45 pm

Quoting Saintsman (Reply 9):
I never had to change them, but I remember in the smoking days recirc fans being gummed up with nicotine. Nobody liked changing them.

I was going to ask that question. I bet that must have been nasty. I'm not near old enough to remember the smoking section days but what was the point of having a "smoking section"? The entire cabin must have been pretty stinky if enoguh people lit up back there. Was there special fans in the section to minimize the smell?
What gets measured gets done.
 
Tod
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RE: Changing Cabin Filters, How Often?

Wed Oct 24, 2007 12:54 pm

Quoting FlyASAGuy2005 (Reply 25):
Was there special fans in the section to minimize the smell?

I've only seen a few smokings sections with special provisions and that was near the end of the era.
Most of those extracted extra air from the cabin via the lav/galley vent system.

Tod
 
CaptOveur
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RE: Changing Cabin Filters, How Often?

Thu Oct 25, 2007 3:53 pm

Quoting FlyASAGuy2005 (Reply 25):
The entire cabin must have been pretty stinky if enoguh people lit up back there. Was there special fans in the section to minimize the smell?

I very vaguely remember my first flight on a Piedmont 737-400 and the back portion of the airplane was a designated smoking section. I do remember that whenever someone lit up the whole airplane became aware of it not long after.
Things were better when it was two guys in a dorm room.
 
TheJoe
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RE: Changing Cabin Filters, How Often?

Wed Oct 31, 2007 7:40 am

Well, the 737-400 has two recirculation fan filters located at the aft end of the forward cargo for those that are interested (behind the access panels)... When it comes to cabin air extraction filters, I hate working on the A330. Ours are configured with 7 toilets, each of which has an extraction filter in the roof which gets changed on a regular basis. Each galley has extraction filters behind the ovens and coffee maker as well which is a pain. When you combine that with changing 12 water filters, you're looking at quite a bit of time spent mucking around! Chapter 25 though, not 21. And 38 for the water filters. I hate chapter 38!  hissyfit 
 
Tod
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RE: Changing Cabin Filters, How Often?

Wed Oct 31, 2007 10:37 am

Quoting TheJoe (Reply 28):
I hate chapter 38!

I like designing chapter 38 systems, but definately do not envy those guys who get to maintain them.

Tod
 
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HAWK21M
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RE: Changing Cabin Filters, How Often?

Wed Oct 31, 2007 5:15 pm

Quoting Tod (Reply 29):
like designing chapter 38 systems

Do you design Chapter 38 systems,What in particular.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tod
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RE: Changing Cabin Filters, How Often?

Thu Nov 01, 2007 5:14 pm

Quoting HAWK21M (Reply 30):
Do you design Chapter 38 systems,What in particular.

Potable water distribution.

Grey water drains from lavs and galleys.

Floor drains.

Vacuum waste.

Blue juice style waste system tank flush and drain plumbing.

Mostly 747, 767 and 777.

Tod
 
Tristarsteve
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RE: Changing Cabin Filters, How Often?

Thu Nov 01, 2007 5:46 pm

Quoting Tod (Reply 29):
I like designing chapter 38 systems, but definately do not envy those guys who get to maintain them

Working on a line station, I reckon 80pc of my work is Chap38.
Especially waste water that doesn't drain away. Why do we have filters in the drain system that clog all the time? Why not make the plumbing a bit bigger so the filter is not required. A pet hate is the drains that lead the spilt coffee away from the bev makers. Although the pipe looks large enough (for a Chap38 drain that is) the only flow is sees is slow coffee. This precipitates out and finally the pipe is a solid mass of coffee. The designer made this pipe very accessible with the galley in the shop! but completely inaccessible with it fitted to the aircraft! I seem to spend my life cleaning toilet sink filters, galley fliters and coffee maker drain lines. A nice Elevator Assymetry Status is a complete surprise!

We are also starting to get blocked vacuum toilet pipes (with paper). The designer of the tank has put a cutting device at the tank entrance, that gets clogged with paper.
We have found that the best way to get it out is a long 2in dia plastic tube. You open the flush valve under the bowl, push the tube into the bowl, then connect the other end to a vacuum toilet service vehicle with an adaptor. Very effective.
 
Tod
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RE: Changing Cabin Filters, How Often?

Thu Nov 01, 2007 7:21 pm

Quoting TristarSteve (Reply 32):
Especially waste water that doesn't drain away.

 checkmark 

Quoting TristarSteve (Reply 32):
Why do we have filters in the drain system that clog all the time?

The theory is that it is better to have an accessible clogged filter than a clog somewhere in never-never land.
It would help if F/A's didn't dump the clogging debris in the first place.

Quoting TristarSteve (Reply 32):
Why not make the plumbing a bit bigger so the filter is not required. A pet hate is the drains that lead the spilt coffee away from the bev makers. Although the pipe looks large enough (for a Chap38 drain that is) the only flow is sees is slow coffee.

The drain lines internal to galleys never ceases to amaze me. It is foolish to use 3/8 drain tube for just about anything other than condensation, but you see it all the time. 1/2 or 3/4 isn't that much harder to design into the galley and guess what, it takes a lot longer to plug from the build up of goo.

Main aircraft grey water drains should all be 1 inch. All mine are, period. Rarely is there a reason to go smaller. Larger than that does not help either because everything still much pass through the drain mast. You don,t want the clog at the heated drain mast unless you want solid cooked goo. Increasing the drain mast opening is not usually an option because dumping more cabin air overboard is not welcome. (I know the outflow valves do that all day, but I still have not won that fight)

In addition to, and sometimes more important than tube diamenter is the issue drain slop.
Obvoiusly the steeper the better. The slower it flows the quicker it grows.

Quoting TristarSteve (Reply 32):
I seem to spend my life cleaning toilet sink filters, galley fliters and coffee maker drain lines.

 yuck 

Tod
 
Tristarsteve
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RE: Changing Cabin Filters, How Often?

Thu Nov 01, 2007 7:30 pm

Quoting Tod (Reply 33):
Increasing the drain mast opening is not usually an option because dumping more cabin air overboard is not welcome.

On the B777 the grey water drains have a valve in them which is normall closed in flight. As pressure builds up behind it it opens to drain the waste. Any idea why this is not more common? Then you can have a bigger drain mast and no loss of pressure.
 
Tod
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RE: Changing Cabin Filters, How Often?

Thu Nov 01, 2007 11:18 pm

Quoting Tristarsteve (Reply 34):
On the B777 the grey water drains have a valve in them which is normall closed in flight. As pressure builds up behind it it opens to drain the waste. Any idea why this is not more common? Then you can have a bigger drain mast and no loss of pressure.

Because prior to the 777, most of the other attempts either sucked and whistled or clogged.

Tod

[Edited 2007-11-01 16:19:00]
 
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HAWK21M
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RE: Changing Cabin Filters, How Often?

Fri Nov 02, 2007 11:01 am

Quoting Tod (Reply 31):
Mostly 747, 767 and 777

What do you use for simulating waste.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tod
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RE: Changing Cabin Filters, How Often?

Fri Nov 02, 2007 2:33 pm

Quoting HAWK21M (Reply 36):
What do you use for simulating waste.

Canned dog food will "get er done"

Tod
 
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HAWK21M
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RE: Changing Cabin Filters, How Often?

Sat Nov 03, 2007 8:53 am

Quoting Tod (Reply 37):
Canned dog food will "get er done"

What quantity is utilised for these tests approx.


regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tod
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RE: Changing Cabin Filters, How Often?

Mon Nov 05, 2007 3:06 pm

Quoting HAWK21M (Reply 38):
What quantity is utilised for these tests approx.

A standard can. (at least the US standard) I don't recall the actual size, but if you use your imagination, just consider a volume slightly large than you can imagine any normal human producing organically.

Tod
 
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HAWK21M
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RE: Changing Cabin Filters, How Often?

Sat Nov 10, 2007 7:42 am

Quoting Tod (Reply 39):
A standard can. (at least the US standard) I don't recall the actual size, but if you use your imagination, just consider a volume slightly large than you can imagine any normal human producing organically.

That would be for testing the Flushing mechanisn.What about the Full Tank indication tests.
Or is something else used.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tod
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RE: Changing Cabin Filters, How Often?

Mon Nov 12, 2007 2:37 am

Quoting HAWK21M (Reply 40):
That would be for testing the Flushing mechanisn.What about the Full Tank indication tests.
Or is something else used.

Since I am usually just adding or relocating lavs, I haven't had to worry about that those tests very often.
Most likely, just follow the AMM.

Tod
 
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HAWK21M
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RE: Changing Cabin Filters, How Often?

Mon Nov 12, 2007 3:45 am

Quoting Tod (Reply 41):
just follow the AMM

I was referring to the Shop tests.But since you dont carry it out.
regds
MEL
I may not win often, but I damn well never lose!!! ;)

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