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Changing Cabin Filters, How Often?  
User currently offlineReadytotaxi From United Kingdom, joined Dec 2006, 3338 posts, RR: 2
Posted (7 years 1 month 2 weeks 4 days 1 hour ago) and read 3536 times:

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!
42 replies: All unread, showing first 25:
 
User currently offlineFr8mech From United States of America, joined Sep 2005, 5603 posts, RR: 15
Reply 1, posted (7 years 1 month 2 weeks 4 days ago) and read 3526 times:

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.
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 2, posted (7 years 1 month 2 weeks 3 days 23 hours ago) and read 3520 times:

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.


User currently offlineTristarsteve From Sweden, joined Nov 2005, 4053 posts, RR: 33
Reply 3, posted (7 years 1 month 2 weeks 3 days 21 hours ago) and read 3509 times:

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.


User currently offlineFr8Mech From United States of America, joined Sep 2005, 5603 posts, RR: 15
Reply 4, posted (7 years 1 month 2 weeks 3 days 19 hours ago) and read 3486 times:

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.
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 5, posted (7 years 1 month 2 weeks 3 days 18 hours ago) and read 3480 times:

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"
User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 6, posted (7 years 1 month 2 weeks 3 days 9 hours ago) and read 3447 times:

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



Think of the brighter side!
User currently offlineFr8Mech From United States of America, joined Sep 2005, 5603 posts, RR: 15
Reply 7, posted (7 years 1 month 2 weeks 3 days 3 hours ago) and read 3396 times:

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.
User currently offlineDALMD88 From United States of America, joined Jul 2000, 2603 posts, RR: 15
Reply 8, posted (7 years 1 month 2 weeks 2 days 21 hours ago) and read 3369 times:

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.


User currently offlineSaintsman From United Kingdom, joined Mar 2002, 2065 posts, RR: 2
Reply 9, posted (7 years 1 month 2 weeks 2 days 12 hours ago) and read 3331 times:

I never had to change them, but I remember in the smoking days recirc fans being gummed up with nicotine. Nobody liked changing them.

User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 10, posted (7 years 1 month 2 weeks 2 days 9 hours ago) and read 3313 times:

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



Think of the brighter side!
User currently offlineTod From Denmark, joined Aug 2004, 1729 posts, RR: 3
Reply 11, posted (7 years 1 month 2 weeks 2 days 4 hours ago) and read 3293 times:

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


User currently offlineSfomb67 From United States of America, joined Dec 2005, 417 posts, RR: 0
Reply 12, posted (7 years 1 month 2 weeks 1 day 15 hours ago) and read 3251 times:

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
User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 13, posted (7 years 1 month 2 weeks 1 day 10 hours ago) and read 3246 times:

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



Think of the brighter side!
User currently offlineFr8Mech From United States of America, joined Sep 2005, 5603 posts, RR: 15
Reply 14, posted (7 years 1 month 1 week 6 days 11 hours ago) and read 3174 times:

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.
User currently offlineB78710 From United Kingdom, joined Mar 2006, 344 posts, RR: 0
Reply 15, posted (7 years 1 month 1 week 6 days 10 hours ago) and read 3172 times:

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!


User currently offlineReadytotaxi From United Kingdom, joined Dec 2006, 3338 posts, RR: 2
Reply 16, posted (7 years 1 month 1 week 6 days 2 hours ago) and read 3140 times:

Thank you everyone for the info, very helpful.


you don't get a second chance to make a first impression!
User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 17, posted (7 years 1 month 1 week 5 days 7 hours ago) and read 3099 times:

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



Think of the brighter side!
User currently offlineTroubleshooter From Germany, joined Feb 2005, 423 posts, RR: 4
Reply 18, posted (7 years 1 month 1 week 5 days ago) and read 3074 times:

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!!!
User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 19, posted (7 years 1 month 1 week 2 days 23 hours ago) and read 2994 times:


B764 Recirculation fan.

regds
MEL



Think of the brighter side!
User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 20, posted (7 years 1 month 1 week 2 days 17 hours ago) and read 2974 times:

Quoting HAWK21M (Reply 19):
B764 Recirculation fan.

Hmm, I wonder how much thrust it makes? Big grin


User currently offlineDALMD88 From United States of America, joined Jul 2000, 2603 posts, RR: 15
Reply 21, posted (7 years 1 month 1 week 2 days 6 hours ago) and read 2941 times:

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.

User currently offlineTod From Denmark, joined Aug 2004, 1729 posts, RR: 3
Reply 22, posted (7 years 1 month 1 week 2 days 5 hours ago) and read 2933 times:

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


User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 23, posted (7 years 1 month 1 week 1 day 11 hours ago) and read 2902 times:


The B737 Gasper fan.
11,500RPM.Approx 5 kgs.
regds
MEL



Think of the brighter side!
User currently offlineTod From Denmark, joined Aug 2004, 1729 posts, RR: 3
Reply 24, posted (7 years 1 month 1 week 1 day 6 hours ago) and read 2887 times:

Quoting HAWK21M (Reply 23):
The B737 Gasper fan

. . . and the rest of the Sundstrand catalog  Wink

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

Tod


25 FlyASAGuy2005 : 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 poin
26 Tod : 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
27 CaptOveur : 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 th
28 Post contains images TheJoe : 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 panel
29 Tod : I like designing chapter 38 systems, but definately do not envy those guys who get to maintain them. Tod
30 HAWK21M : Do you design Chapter 38 systems,What in particular. regds MEL
31 Tod : Potable water distribution. Grey water drains from lavs and galleys. Floor drains. Vacuum waste. Blue juice style waste system tank flush and drain p
32 TristarSteve : 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 sy
33 Post contains images Tod : 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 th
34 Tristarsteve : 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
35 Tod : Because prior to the 777, most of the other attempts either sucked and whistled or clogged. Tod[Edited 2007-11-01 16:19:00]
36 HAWK21M : What do you use for simulating waste. regds MEL
37 Tod : Canned dog food will "get er done" Tod
38 HAWK21M : What quantity is utilised for these tests approx. regds MEL
39 Tod : 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 tha
40 HAWK21M : That would be for testing the Flushing mechanisn.What about the Full Tank indication tests. Or is something else used. regds MEL
41 Tod : 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
42 HAWK21M : I was referring to the Shop tests.But since you dont carry it out. regds MEL
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