KELPkid
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What Happened On This 752? (Lav Related)

Sat Jul 28, 2007 9:33 am

Hi,

Well, I flew out to the East Coast last Saturday on a P&W powered 752, and the leg that this happened on was SLC-BWI (I'm sure you guys can put 2+2 together and guess the airline  Wink ). Well, on this particular leg, I got up to use the forward lav, and the first thing I noticed was that the flapper in the crapper was hanging ajar. Well, I did my business, and flushed (maybe I really didn't need to, since the flapper didn't shut and it all went down anyways), and the blue lav juice just kept flowing and flowing and flowing for what seemed like an eternity instead of the usual short burst you get in an airline lav.

At this point, we were about 1 hour into our 4 hour flight....

Then (~30 minutes later), my mother in law (who's flying in my party) goes to one of the aft lavs, and comes back about 10 minutes later. She says she had to summon a flight attendant after the toilet won't flush... shortly after she takes her seat, we hear "Ding! Ladies and gentlemen, we are currently experiencing a malfunction of the lavoratory system and ask that you not use the lavatories for the remainder of the flight..."  Wow!  Yeah sure  Angry

Anyone know what happened here?

P.S. My internet access is currently sporadic, as I am on the road for the next week.
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
dl757md
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RE: What Happened On This 752? (Lav Related)

Sat Jul 28, 2007 2:18 pm

Can't tell you what happened because I don't know the details of what happened but I can tell you that our 752s have 4 lavs and they are all independent of each other. You indicate problems with two of them, although the first doesn't sound like a problem that would cause it to be locked out. It did stop flushing, right? It would be unlikely, not impossible, but unlikely that all 4 lavs would malfunction during the same flight. As I said they are all self contained units independent of each other. Anyway, without more details I can't tell you much more that wouldn't be pure speculation. Sorry about the inconveniance.

DL757Md
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Buzz
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RE: What Happened On This 752? (Lav Related)

Sat Jul 28, 2007 7:38 pm

Hi KELP kid, Buzz here. We've also got 757's in our fleet... and like the Delta guy I could only make an educated guess.
That blue juice pump runs on a timer... sounds like it's time to change it. I'm trying to think if there's a common power circuit breaker to all 4 lavs... I'm thinking they're isolated. Just a run of bad luck on that airplane I guess.

Most of the time our problem is that people drop "foreign items" into the pooper, holds up the dump valve so the blue juice drains away into the big dump pipe... no flush. Good thing I don't have much sense of smell when I fix things like this.

My wife and I are going to the Steam Up down by Salem OR. I doubt I'll find any steam powered airplanes (grin) But I'll be looking at the sky anytime somebody flies by.

g'day
 
MD11Engineer
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RE: What Happened On This 752? (Lav Related)

Sun Jul 29, 2007 2:59 pm

Quoting Buzz (Reply 2):
My wife and I are going to the Steam Up down by Salem OR. I doubt I'll find any steam powered airplanes (grin) But I'll be looking at the sky anytime somebody flies by.

The C-54 I worked on had the old "bucket in a box" crapper. How about your DC-3s?  Silly

Jan
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HAWK21M
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RE: What Happened On This 752? (Lav Related)

Mon Jul 30, 2007 3:53 pm

Quoting KELPkid (Thread starter):
since the flapper didn't shut and it all went down anyways), and the blue lav juice just kept flowing and flowing and flowing for what seemed like an eternity instead of the usual short burst you get in an airline lav.

The Liquid system is a recirculatory one with the Fluid reused from Tank to Motor filter assy to Commode to Tank.The Flapper in the commode shuts with spring tension.
If the Timer did not autoshut off.The CB would trip or motor burn out.Unless the Dump valve is leaking or stuck open.You wont loose the Blue Juice.

Quoting KELPkid (Thread starter):
had to summon a flight attendant after the toilet won't flush

Was that to suggest the Flush motor was functioning but no blue juice or The flush motor was u/s.

regds
MEL
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FlyingColours
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RE: What Happened On This 752? (Lav Related)

Tue Jul 31, 2007 2:55 am

There was a very good thread started last year, and the subject was, you guessed it - aircraft lavs. Although it ran for 68 posts there is a lot of great info in there, specifically a few bits on the 757 (inc a bit from myself - as a flight attendant).

http://www.airliners.net/discussions...id=168886&s=FlyingColours#ID168886

Quoting HAWK21M (Reply 4):
The Liquid system is a recirculatory one with the Fluid reused from Tank to Motor filter assy to Commode to Tank.The Flapper in the commode shuts with spring tension.
If the Timer did not autoshut off.The CB would trip or motor burn out.Unless the Dump valve is leaking or stuck open.You wont loose the Blue Juice.

In all fairness, those flaps are usually quite worn out and don't close properly. I know if the toilet motor was still running after 20 seconds we would manually turn the motor off and pull the CB. When I was back at Excel & Islandsflug we were supposed to check the lavs every 20 minutes and one of these checks was to see if the motor stops after 10 seconds.
As for the blue juice, if we flushed and nothing came out we would just pour 2 pots of water in there, of course if the dump valve is open then that water will be lost.

As was mentioned in the thread I linked to, it says that on the 757 the "Recycle" type of Lavs have independent tanks, I know the pneumatic ones are all linked, so if one breaks they all do...

Phil
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dl757md
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RE: What Happened On This 752? (Lav Related)

Tue Jul 31, 2007 7:55 am

Quoting FlyingColours (Reply 5):
I know the pneumatic ones are all linked, so if one breaks they all do...

Not necessarily. Generally in a vacuum waste system each toilet has a flush switch, flush control unit, flush valve, and a rinse valve. The failure of any of those components would INOP only the specific lav that it was located at. Additionally, waste line blockages can affect one or more toilets but rarely all of them as there is more than one waste line inlet to the waste tank so you would need to have multiple blockages to INOP all the lavs.

DL757Md
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Tristarsteve
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RE: What Happened On This 752? (Lav Related)

Wed Aug 01, 2007 6:18 am

Quoting Dl757md (Reply 6):
The failure of any of those components would INOP only the specific lav that it was located at.

One thing we must remember is that 90pc of toilet failures are because the tank is full. On a recycling toilet (where you see blue water when it flushes) this is pretty obvious. On a vacuum toilet there is a level switch at the top of the tank. When the tank is full this just shuts down the system. On a large aircraft, like the B777 there are 3 waste tanks, and one tank filling up will only shut down the toilets connected to it. But a small aircraft like an A320 only has one tank. When it's full all the toilet flushes are disabled.
The biggest defect on toilet systems is that they were not serviced before departure. On short sectors this is OK as an A320 toilet tank will last about 3 2hr sectors, but on a B777 then the tanks will fill up mid flight and thats it.
But both aircraft have a display that shows how full the tanks are. All that is needed is for the cabin crew to refuse to depart if they are not serviced. Fat chance.
 
dl757md
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RE: What Happened On This 752? (Lav Related)

Wed Aug 01, 2007 7:01 am

Quoting Tristarsteve (Reply 7):
One thing we must remember is that 90pc of toilet failures are because the tank is full.

Not where I work. Toilets are serviced at least every other flight. I have in 8 years of line mtc seen only a handful of lavs that came in locked out because of full tanks and they are invariably because of ground delays or diversions. Compare that to during the same time I have removed obstructions from the dump valve of 757 lav tanks 116 times. At Delta it's just not much of an issue let alone THE MAIN issue. I've also been on over 800 flights on Delta and have yet to encounter a lav locked out due to being full on any of these flights. Why do we have such wildly different experiences on the same subject?

Quoting Tristarsteve (Reply 7):
The biggest defect on toilet systems is that they were not serviced before departure.

I guess Delta just has an effective servicing policy that prevents full lav tanks.

DL757Md
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BAE146QT
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RE: What Happened On This 752? (Lav Related)

Wed Aug 01, 2007 8:43 am

Quoting Dl757md (Reply 8):
I guess Delta just has an effective servicing policy that prevents full lav tanks.

I reckon that's because of all the fried chicken, gravy and grits. Last thing you want on your plane departing ATL is 200 rednecks like me holding back a gutful of southern food. It'd be carnage by the time you got to Chatanooga.
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FlyingColours
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RE: What Happened On This 752? (Lav Related)

Wed Aug 01, 2007 7:42 pm

Quoting Tristarsteve (Reply 7):
But both aircraft have a display that shows how full the tanks are. All that is needed is for the cabin crew to refuse to depart if they are not serviced. Fat chance.

Yeah the 737NG has a panel in the cabin so we can check the tanks, also shows the amount of portable water onboard - best not get the two mixed up....

Quoting Tristarsteve (Reply 7):
On a recycling toilet (where you see blue water when it flushes) this is pretty obvious

You would think that wouldn't you? One day we departed back to Manchester from SKG and only realised shortly after takeoff that 3 of the 4 lavs were almost completley full (specifically 2 which were adjacent to my crew station). It turns out that in SKG you have to request a service, usually everywhere else does it straight away and you only ask them if you don't want a service (ala light loads on the inbound)).

Quoting BAe146QT (Reply 9):
I reckon that's because of all the fried chicken, gravy and grits. Last thing you want on your plane departing ATL is 200 rednecks like me holding back a gutful of southern food. It'd be carnage by the time you got to Chatanooga.

Hahaha, you ever seen 233 holidaymakers kick off because you told them there is only 1 toilet avaliable?....

Phil
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HAWK21M
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RE: What Happened On This 752? (Lav Related)

Wed Aug 01, 2007 10:56 pm

Quoting Tristarsteve (Reply 7):
The biggest defect on toilet systems is that they were not serviced before departure.

Refilling to a certain level providing adequate space helps.
regds
MEL
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Tristarsteve
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RE: What Happened On This 752? (Lav Related)

Thu Aug 02, 2007 12:16 am

Quoting Dl757md (Reply 8):
Compare that to during the same time I have removed obstructions from the dump valve of 757 lav tanks 116 times. At Delta it's just not much of an issue let alone THE MAIN issue

On our European network we service lavs at main base, and on nightstops. This is sufficient. But the problem is that when the lav man does not service the lavs, no one seems to notice. I have been trying to educate cabin crew for years, but they still manage not to react when they leave main base with the indicator showing 75pc full.

The issue of blocked dumpvalves has been greatly reduced lately. We have removed items from the lavs that block the dump valves. We have no small bottles of perfume, no bars of soap, water degradable tissues, no cotton hand towels. Since all this was introduced a couple of years ago, blocked open dump valves seem to be a thing of the past.

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