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zipsy
Topic Author
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Drain Mast Question

Sat Aug 07, 2010 3:42 am

I have just joined this very informative forum and I always wondered about the plumbings on modern airliners.Recently I saw a BA A320 spurting water from the drain mast.I'm just wondering how often do they get blocked and how do you unblock them?The opening must be tiny so it must be difficult to get in there.
 
AirframeAS
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Joined: Thu Feb 05, 2004 3:56 pm

RE: Drain Mast Question

Sat Aug 07, 2010 4:59 am

Quoting Zipsy (Thread starter):
'm just wondering how often do they get blocked and how do you unblock them?The opening must be tiny so it must be difficult to get in there.

Those drain masts come from the sinks in the lavs and the galleys. They have a one way opening so pressurization is not really lost while inflight. Someone posted a video about this on another thread while the aircraft was inflight. It was awesome to see!

Edit: grammar

[Edited 2010-08-06 22:00:11]
A Safe Flight Begins With Quality Maintenance On The Ground.
 
charliecossie
Posts: 412
Joined: Wed Oct 10, 2001 5:17 am

RE: Drain Mast Question

Sat Aug 07, 2010 6:46 am

Quoting AirframeAS (Reply 1):
They have a one way opening

Are you sure about that?
 
Tristarsteve
Posts: 3663
Joined: Tue Nov 22, 2005 11:04 pm

RE: Drain Mast Question

Sat Aug 07, 2010 8:50 am

Quoting charliecossie (Reply 2):
Quoting AirframeAS (Reply 1):
They have a one way opening

Are you sure about that?

The only airliner I know with a valve in the grey water pipes is the B777. Just before the drain mast it has a pressure operated valve. When sufficient waste water has accumulated above the valve, the valve opens to let it out, then closes again. It is always open on the ground.
All other drain masts are open to the cabin, and air escapes all the time.

And yes they are getting blocked regularly. The simplest way to stop this is educate the cabin crew. Sinks are for water. Milk and orange juice goes into the lav. (bowl not sink).

The B787 has no drain masts. The sinks drain into the toilet tanks.
 
AirframeAS
Posts: 9811
Joined: Thu Feb 05, 2004 3:56 pm

RE: Drain Mast Question

Sat Aug 07, 2010 1:14 pm

Quoting charliecossie (Reply 2):
Are you sure about that?

As someone who has done c-checks on Airbuses, yes. Also, see reply 3.

Quoting Tristarsteve (Reply 3):
The B787 has no drain masts. The sinks drain into the toilet tanks.

That has got to be one big-assed waste take in there!!!!  Wow!
A Safe Flight Begins With Quality Maintenance On The Ground.
 
Dalmd88
Posts: 3131
Joined: Fri Jul 28, 2000 3:19 am

RE: Drain Mast Question

Sat Aug 07, 2010 2:51 pm

The best way to unplug a drain is with compressed air. It can make a mess, but it is really the best way. During c check we clean them with a enzymatic solution.
 
aogdesk
Posts: 748
Joined: Wed Jun 09, 2004 2:26 am

RE: Drain Mast Question

Sat Aug 07, 2010 3:14 pm

They're not really drain masts per se, but merely protruding objects for mechanics to bump their heads on. Very mean-spirited design engineers at Boeing and Airbus.
 
zipsy
Topic Author
Posts: 50
Joined: Tue Jul 27, 2010 2:06 am

RE: Drain Mast Question

Sat Aug 07, 2010 3:24 pm

Do you put the compressed air in the sink or in the drain mast?How big is the opening in the mast?Can't be very big.Is there any difference between Boeing,Airbus and Embraer?I saw a photo with black sludge coming out of an Embraer 195s mast which reminded me of a bathroom sink I recently unblocked.It was truly disgusting.The smell was unbearable.
 
boeing767mech
Posts: 806
Joined: Fri Dec 15, 2000 5:03 pm

RE: Drain Mast Question

Sat Aug 07, 2010 3:33 pm

Quoting Zipsy (Thread starter):
.I'm just wondering how often do they get blocked and how do you unblock them?The opening must be tiny so it must be difficult to get in there.

I don't know about the BUS during C-checks. But on the line if we have a sink drain plugged we pump the airplane up to about 4 PSI on the ground and hope it clears the clog. If not we have a toilet snake (yes a toilet snake in the sink drain) that we use to help clear the clog, which 99% of the time is coffee grounds and wine with a dash of milk which has been poured down the drains (wonderful smell when you get it on yourself). Once we get a slow running drain we will head to the galley and grab a couple cans of soda in the red can (copyright thing) and pour it down the drains let it sit for a couple minutes and then pump the airplane back up to 4 PSI. hopefully the action of the carbonation and 4PSi will blow the blockage out. If not to the hangar we go and start ripping cargo liners out and chasing drain lines until we find the clog.

This is also a crowd pleaser when you do this with the lav truck hooked up, because the lav guy hooked up before your ground spotter could get to him and tell him not to hook up.



Just another adverture on the line. It's not always MEL's and crosswords like some people think.

David
Never under-estimate the predictably of stupidty
 
AirframeAS
Posts: 9811
Joined: Thu Feb 05, 2004 3:56 pm

RE: Drain Mast Question

Sat Aug 07, 2010 5:54 pm

Quoting Zipsy (Reply 7):
How big is the opening in the mast?

Not very. It is regular rigid tubing no more than 3-4 cm wide. And the mast itself is pretty big. Weird, huh?
A Safe Flight Begins With Quality Maintenance On The Ground.
 
charliecossie
Posts: 412
Joined: Wed Oct 10, 2001 5:17 am

RE: Drain Mast Question

Sat Aug 07, 2010 7:50 pm

Quoting AirframeAS (Reply 4):
As someone who has done c-checks on Airbuses, yes. Also, see reply 3.
Quoting Tristarsteve (Reply 3):
The only airliner I know with a valve in the grey water pipes is the B777.
Quoting Tristarsteve (Reply 3):
All other drain masts are open to the cabin, and air escapes all the time.

Yep, seen that. He seems to be contradicting you.
 
MD11Engineer
Posts: 13899
Joined: Sun Oct 26, 2003 5:25 am

RE: Drain Mast Question

Sat Aug 07, 2010 8:45 pm

Quoting Tristarsteve (Reply 3):
The only airliner I know with a valve in the grey water pipes is the B777. Just before the drain mast it has a pressure operated valve. When sufficient waste water has accumulated above the valve, the valve opens to let it out, then closes again. It is always open on the ground.
All other drain masts are open to the cabin, and air escapes all the time.

On our 737-800s and on LH´s 747-400, the lavatory washbasins (and the galleys) have float valves installed, which close the drain line if there is no water in it.

Jan
Je Suis Charlie et je suis Ahmet aussi
 
zipsy
Topic Author
Posts: 50
Joined: Tue Jul 27, 2010 2:06 am

RE: Drain Mast Question

Sun Aug 08, 2010 12:22 am

Quoting AirframeAS (Reply 9):
Not very. It is regular rigid tubing no more than 3-4 cm wide. And the mast itself is pretty big. Weird, huh?

That's not very big,not surprising it gets clogged with all sorts of nasties.I wonder what that really bad smell was when I was walking around Heathrow the other day,it smelled like a blocked drain if not worse.The smell came directly from one of the A340s sitting idle.

[Edited 2010-08-07 17:23:17]
 
zipsy
Topic Author
Posts: 50
Joined: Tue Jul 27, 2010 2:06 am

RE: Drain Mast Question

Sun Aug 08, 2010 12:33 am

Quoting aogdesk (Reply 6):
They're not really drain masts per se, but merely protruding objects for mechanics to bump their heads on. Very mean-spirited design engineers at Boeing and Airbus

Are these things hot on the ground or only in flight?Could be dangerous if you bump your head and also get burned.I wonder if anyone here ever got baptised by a jet?Seen a guy recently in Manchester doing his walk around and the jet started piddling very near his face He didn't seem to care much.
 
wn700driver
Posts: 1475
Joined: Wed Aug 29, 2001 10:55 pm

RE: Drain Mast Question

Sun Aug 08, 2010 12:43 am

Quoting aogdesk (Reply 6):

They're not really drain masts per se, but merely protruding objects for mechanics to bump their heads on. Very mean-spirited design engineers at Boeing and Airbus.

Don't forget burned by heated masts as well!

Quoting Zipsy (Reply 13):
Are these things hot on the ground or only in flight

Should only be in flight. The purpose is to keep it from getting clogged with Ice. As implied above, I've actually smarted a hand or two on a mast that was heated, on the ground, when it should obviously not have been. That's life though...
Base not your happiness on the deeds of others, for what is given can be taken away. No Hope = No Fear
 
AirframeAS
Posts: 9811
Joined: Thu Feb 05, 2004 3:56 pm

RE: Drain Mast Question

Sun Aug 08, 2010 4:45 am

Quoting wn700driver (Reply 14):
Don't forget burned by heated masts as well!

Yeah, those tend to warm up pretty quick. They are hot so that the water does not freeze up while being disposed in-flight.
A Safe Flight Begins With Quality Maintenance On The Ground.
 
boeing767mech
Posts: 806
Joined: Fri Dec 15, 2000 5:03 pm

RE: Drain Mast Question

Sun Aug 08, 2010 3:22 pm

Quoting Zipsy (Reply 12):
it smelled like a blocked drain if not worse.The smell came directly from one of the A340s sitting idle.

The wonderful smell also could have come out of the blower exhaust for the lav waste tanks. On the ground they use a blower motor to produce the vaccum pressure to flush the toilets. At about 14K feet they use cabin air pressure to flush the toilets Since the outside pressure is lower. At these that is the way it works on the 767's. But I have walked behind a 767 when they flushed the toilets and the smell out of the exhaust is enough to knock you on the floor.

David
Never under-estimate the predictably of stupidty
 
sgtusmc96
Posts: 38
Joined: Wed Apr 04, 2007 3:11 pm

RE: Drain Mast Question

Mon Aug 09, 2010 5:12 am

One of the best ways we found to unclog a lav or galley sink is to put a house in the vacuum toilet and suck everything out of the sinks using the toilet vacum. If that doesn't work. Compressed air blown in the drain mast works wonders. Just have to make sure the F/A's aren't upstairs. Tends to be messy. If we could just teach the very slow to learn and stuck up F/A's not to put coffe grounds and milk down the drains we wouldn't have the problem. But they never listen or learn. Lol that's life o. The line I guess.
 
zipsy
Topic Author
Posts: 50
Joined: Tue Jul 27, 2010 2:06 am

RE: Drain Mast Question

Mon Aug 09, 2010 12:50 pm

That sounds like fun!I can well imagine the mess that would make,specially milk which curdles nicely.I can just picture this,milk,wine,coffee grounds,add some gravy for good measures and you get some sort of cottage cheese,lol.I bet that smells lovely!It's bad enough to deal with toothpaste,shaving stubbles,long hair which I have to deal with in bathroom sinks.Last week I pulled nearly 2 metres of hair with gunge out of a sink drain.Couldn't believe my eyes.People put all sorts of crap down there.
Which aircraft is the worst to unblock?Do Boeing,Airbus,Embraer all use the same masts and drains?
 
Skydrol
Posts: 1045
Joined: Fri Oct 03, 2003 12:01 pm

RE: Drain Mast Question

Mon Aug 09, 2010 2:42 pm

Quoting Zipsy (Reply 18):
Which aircraft is the worst to unblock?Do Boeing,Airbus,Embraer all use the same masts and drains?

From my experience, the drain masts for the upper deck on Boeing 747-100s. The long drain lines were a nightmare when blocked. And you haven't lived until you get to experience a lav with the mirror, walls and ceiling covered with pink cottage cheese when a blocked drain mast is pressurized with compressed air.




LD4
∙ ---{--« ∙ ----{--« ∙ --{-« ∙ ---{--« ∙ --{--« ∙ --{-« ∙ ----{--« ∙
 
roseflyer
Posts: 9602
Joined: Fri Feb 13, 2004 9:34 am

RE: Drain Mast Question

Mon Aug 09, 2010 2:52 pm

I have had quite a few experiences with drain masts. Pouring coffee pots when the bag breaks into the sink does a great job of clogging them. It can get costly and cause delays as they have to be unclogged.

Quoting AirframeAS (Reply 9):
Quoting Zipsy (Reply 7):
How big is the opening in the mast?

Not very. It is regular rigid tubing no more than 3-4 cm wide. And the mast itself is pretty big. Weird, huh?

I believe the openings are 1/8th and 1/4 inches.

Quoting Zipsy (Reply 13):

Are these things hot on the ground or only in flight?Could be dangerous if you bump your head and also get burned.I wonder if anyone here ever got baptised by a jet?Seen a guy recently in Manchester doing his walk around and the jet started piddling very near his face He didn't seem to care much.

Some don't realize, but the drain mast also has a hydraulic fluid dump on it too. It is rarely used, but when the airplane gets overserviced and has too much fluid in the reservoirs, it dumps out the drain mast. I was working on a plane when we accidentally raised the flaps without the airplane configured correctly. When the pressure relief valves released on the hydraulic reservoirs, the fluid launched out the drain mast and blasted 30 feet. That was a mess!
If you have never designed an airplane part before, let the real designers do the work!
 
zipsy
Topic Author
Posts: 50
Joined: Tue Jul 27, 2010 2:06 am

RE: Drain Mast Question

Mon Aug 09, 2010 4:49 pm

Quoting RoseFlyer (Reply 20):
Some don't realize, but the drain mast also has a hydraulic fluid dump on it too. It is rarely used, but when the airplane gets overserviced and has too much fluid in the reservoirs, it dumps out the drain mast. I was working on a plane when we accidentally raised the flaps without the airplane configured correctly. When the pressure relief valves released on the hydraulic reservoirs, the fluid launched out the drain mast and blasted 30 feet. That was a mess!

That is interesting,I didn't know that.Isn't hydraulic fluid dangerous to get on your skin?My son is always saying how that stuff smells really strong.He is learning to be a car mechanic.
 
planenut767
Posts: 54
Joined: Thu Jun 11, 2009 4:45 pm

RE: Drain Mast Question

Mon Aug 09, 2010 6:35 pm

Quoting RoseFlyer (Reply 20):
Some don't realize, but the drain mast also has a hydraulic fluid dump on it too. It is rarely used, but when the airplane gets overserviced and has too much fluid in the reservoirs, it dumps out the drain mast. I was working on a plane when we accidentally raised the flaps without the airplane configured correctly. When the pressure relief valves released on the hydraulic reservoirs, the fluid launched out the drain mast and blasted 30 feet. That was a mess!

What airplanes have them where they're going to the drain mast? Every airplane I've seen with hydraulic reservoir drains has it's own line straight out of the system and aircraft, while the engines have their own drain masts and usually a separate drain line depending on the fluid type and engine component going into the mast.
 
roseflyer
Posts: 9602
Joined: Fri Feb 13, 2004 9:34 am

RE: Drain Mast Question

Mon Aug 09, 2010 6:45 pm

Quoting planenut767 (Reply 22):

What airplanes have them where they're going to the drain mast?

Not the same, but located near.
If you have never designed an airplane part before, let the real designers do the work!
 
Tod
Posts: 1716
Joined: Sat Aug 28, 2004 6:51 am

RE: Drain Mast Question

Tue Aug 10, 2010 1:45 am

Quoting Skydrol (Reply 19):
From my experience, the drain masts for the upper deck on Boeing 747-100s. The long drain lines were a nightmare when blocked. And you haven't lived until you get to experience a lav with the mirror, walls and ceiling covered with pink cottage cheese when a blocked drain mast is pressurized with compressed air.

The wonderful pink cottage cheese come from dairy product, wine and heated drain lines.
A magic combination.

This is why the 744 got rid of the heated drain lines that were present on earlier 747.
The only drain heat on the 744 is at the drain masts.

Tod
 
MD11Engineer
Posts: 13899
Joined: Sun Oct 26, 2003 5:25 am

RE: Drain Mast Question

Tue Aug 10, 2010 3:20 am

Quoting planenut767 (Reply 22):
What airplanes have them where they're going to the drain mast? Every airplane I've seen with hydraulic reservoir drains has it's own line straight out of the system and aircraft, while the engines have their own drain masts and usually a separate drain line depending on the fluid type and engine component going into the mast.

The 737 for example runs the pressure relief valves of both system reservoirs into an (unheated) drain mast just aft of the left main wheel well. This mast also contains the drain for the APU fuel line shroud.

Jan
Je Suis Charlie et je suis Ahmet aussi
 
tdscanuck
Posts: 8573
Joined: Wed Jan 11, 2006 7:25 am

RE: Drain Mast Question

Tue Aug 10, 2010 7:16 am

Quoting AirframeAS (Reply 4):
Quoting Tristarsteve (Reply 3):
The B787 has no drain masts. The sinks drain into the toilet tanks.

That has got to be one big-assed waste take in there!!!!

Two big-assed waste tanks, actually. Exactly the same size as the two big-assed potable water tanks (net zero).

Quoting aogdesk (Reply 6):
They're not really drain masts per se, but merely protruding objects for mechanics to bump their heads on.

Bastard cousin of the lower-lobe VHF antenna.

Quoting Zipsy (Reply 21):
That is interesting,I didn't know that.Isn't hydraulic fluid dangerous to get on your skin?My son is always saying how that stuff smells really strong.He is learning to be a car mechanic.

Aircraft hydraulic fluid is different stuff than car hydraulic fluid but, yes, Skydrol is nasty and you don't want to get it on your skin.

Tom.

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