Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

Unblocking a drain mast

Tech Log The very best in practical technical discussion on the web

Unblocking a drain mast

Old 21st Aug 2012, 12:44
  #1 (permalink)  
Thread Starter
 
Join Date: Jan 2010
Location: Cloud 9
Posts: 38
Unblocking a drain mast

How do you guys unblock a grey water drain mast?Which aircraft (Boeing,Airbus,Embraer) is the worst for clogging?What's your worst experience in dealing with drain masts?Love to hear your storys,also please include some pics
anne747380 is offline  
Old 21st Aug 2012, 16:16
  #2 (permalink)  
 
Join Date: May 2009
Location: sfo
Age: 67
Posts: 300
Boeing experience only

One of the most important tools is a 2 liter bottle of Coke. I also keep a 10' length of plastic-coated 1/8 inch cable to snake out the drain mast from the outside. Don't stand in line with the mast, last time I got a geyser of brownish cottage cheese.
sb_sfo is offline  
Old 21st Aug 2012, 16:29
  #3 (permalink)  
 
Join Date: Jul 2006
Location: East of LGB
Age: 65
Posts: 619
....snake out the drain mast from the outside.
Don't talk while you are clearing it either.
11Fan is offline  
Old 21st Aug 2012, 17:49
  #4 (permalink)  
Thread Starter
 
Join Date: Jan 2010
Location: Cloud 9
Posts: 38
I have heard of the famous cottage cheese,was it in a 747 by any chance?The guys were almost sick when they smelt the cottage cheese.I can imagine that the smell of these masts must be absolutly awful.Amazing,there is a snake small enough to fit in the tiny holes of a drain mast.Do you get blocked masts mainly on bigger jets like the 747 or 777 or do the smaller ones like the Embraer E-Jets also suffer this?Sorry about all the questions but I find it all very interesting.Which jets out of Airbus,Boeing,Embraer,get the most problems with blocked masts?Worst story I've heard,a guy was working on a mast and someone up in the lav had a pee in the sink,
anne747380 is offline  
Old 21st Aug 2012, 18:40
  #5 (permalink)  
 
Join Date: Dec 1998
Location: .
Posts: 2,945
Cool

3000psi from an n2 rig attached to the mast normally clears it!
Mind you it'll take a few hours to clean all the galleys out.
If only the CC didn't put milk and red wine and coffee grains down the sinks in the first place.
Worst I've seen recently on a 744 was a total blockage of around 10 feet of drain line in the fwd cargo bay, ceiling panels down, lots of pipes out and half in dia steel rod, just about cleared it!
spannersatcx is online now  
Old 21st Aug 2012, 23:30
  #6 (permalink)  
 
Join Date: Jun 2005
Location: position data invalid
Posts: 50
Do you get blocked masts mainly on bigger jets like the 747 or 777 or do the smaller ones like the Embraer E-Jets also suffer this?
Boeing introduced the GWDU on B777 which has helped tremendously to prevent blocked drains.
cod liver oil is offline  
Old 22nd Aug 2012, 01:09
  #7 (permalink)  
Thread Starter
 
Join Date: Jan 2010
Location: Cloud 9
Posts: 38
Interesting stuff,are these masts hot on the ground as well as in the air?Hope they are not too hot,otherwise you guys get burned or do you wear special gloves?Have all aircraft got the same size holes in the mast or is there a difference?Love to see some photos of them.
anne747380 is offline  
Old 22nd Aug 2012, 03:46
  #8 (permalink)  
 
Join Date: Apr 2004
Location: Planet Earth
Posts: 1,894
'Boeing introduced the GWDU on B777 which has helped tremendously to prevent blocked drains'


Thank god they did that, er what is a GWDU
stilton is offline  
Old 22nd Aug 2012, 05:02
  #9 (permalink)  
 
Join Date: Jul 2006
Location: East of LGB
Age: 65
Posts: 619
what is a GWDU
Galley Waste Disposal Unit.

Full Disclosure, I had to look it up in the Aircraft Maintenance Manual.
11Fan is offline  
Old 22nd Aug 2012, 05:13
  #10 (permalink)  
 
Join Date: Nov 2005
Location: australia
Posts: 333
The toilet in the galley, connected to the toilet tank system
domo is offline  
Old 22nd Aug 2012, 09:48
  #11 (permalink)  
 
Join Date: Oct 2006
Location: berkshire
Posts: 0
found a cap off the free tooth paste blocking the waste pipe once took couple of hours to clear with hold panels down and pipes out.
orange juice the type with the bits left in blocks pipes a treat.
a coat hanger wire up the drain mast often cured blockages
mitzy69 is offline  
Old 22nd Aug 2012, 09:50
  #12 (permalink)  
 
Join Date: Mar 2005
Location: sandhurst
Posts: 25
On the Boeings the masts are heated on the ground, but with a lower voltage than in the air, therefore they are hot they are not HOT. Don't know about Airbuses.
t6 sparky is offline  
Old 22nd Aug 2012, 15:01
  #13 (permalink)  
 
Join Date: May 2009
Location: sfo
Age: 67
Posts: 300
The incident I referred to was a 777. I took a pic of the resulting mess on the ramp, but it doesn't do it justice. 744s are also fun, in that there are about 9 different drains that lead to the forward mast.

3000psi from an n2 rig attached to the mast normally clears it!
Reminds me of something I saw in the 80s. CO had just gotten 4 A300s from Eastern, and I watched as some of their techs tried to deal with a blocked rear lav. Apparently they thought it would be a good idea to hook up an airstarter to the dump chute and give it a blast. They had a guy in the lav holding a blanket over the toilet (must have been junior). Long story short, I don't know what happened to him, but these aircraft had lav walls made of vinyl with holes about every 1/4 inch (for acoustic suppression?) and most of the holes were filled!
sb_sfo is offline  
Old 22nd Aug 2012, 20:06
  #14 (permalink)  
Thread Starter
 
Join Date: Jan 2010
Location: Cloud 9
Posts: 38
That sounds like fun!So the Trippie can be a messy baby too,I was enjoying a nice cottage cheese sandwich,whilst reading this but suddenly lost my appetite
Any chance of that pic,cheers,now back to my sandwich!
anne747380 is offline  
Old 23rd Aug 2012, 00:30
  #15 (permalink)  
 
Join Date: Feb 2004
Location: Australia
Posts: 1,300
Boeing introduced the GWDU on B777 which has helped tremendously to prevent blocked drains.
ah.. you mean that over-engineered waste disposal unit which tends to break down a lot? Instead of coffee grinds, I'm sure the flight attendants are finding more solid things to dispose of, like coffee sachets and tea bags, which lead to even more serious blockages
NSEU is offline  
Old 23rd Aug 2012, 00:45
  #16 (permalink)  
 
Join Date: Jun 2005
Location: position data invalid
Posts: 50
Any chance of that pic


cod liver oil is offline  
Old 23rd Aug 2012, 17:42
  #17 (permalink)  
Thread Starter
 
Join Date: Jan 2010
Location: Cloud 9
Posts: 38
What's the diameter of the openings of these masts?The Airbus one looks tiny.The Boeing one looks so big in comparison.
anne747380 is offline  
Old 24th Aug 2012, 15:36
  #18 (permalink)  
 
Join Date: May 2009
Location: sfo
Age: 67
Posts: 300
The waste drain lines in Boeings are 1/2" ID, I believe, and you wouldn't want the outlet to be much smaller.
sb_sfo is offline  
Old 25th Aug 2012, 11:14
  #19 (permalink)  
Thread Starter
 
Join Date: Jan 2010
Location: Cloud 9
Posts: 38
How about the Embraer E-Jets,are they prone to clog as well?Also why do some masts have two holes and others only have one?I had a look on a E-195 and I saw 2 openings in the mast,does she pee in stereo,
anne747380 is offline  
Old 25th Aug 2012, 14:45
  #20 (permalink)  
 
Join Date: Sep 2010
Location: earth
Posts: 1,342
The answer is simple, big jets have more pax, more ditzy flight attendants, they serve much more food and drink & longer stretches of drain hose. On most e-jets you would be lucky to get a bag with a bottle of water and a packet of salty nuts in it.
grounded27 is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.