FlyASAGuy2005 From United States of America, joined Sep 2007, 7305 posts, RR: 7
Reply 10, posted (5 years 1 month 3 weeks 16 hours ago) and read 6523 times:
From what I was told, it was ultimately due to weight. My instructor but himself through flight school working cabin service and lavs and he would always say "on the older planes you had to deal with the first class shit and coach shit. Belive me, there is no difference in smell"
AA737-823 From United States of America, joined Mar 2000, 6215 posts, RR: 10
Reply 12, posted (5 years 1 month 6 days ago) and read 5997 times:
Quoting HAWK21M (Reply 11): Is the term Gravity System or Recirculating system?
"Gravity system" is not an appropriate term.
Recirc might be, but I do know there were two design philosophies in the blue-water systems, the one we're used to, and the design employed by Lockheed on the L-1011. I forget all the details, but as I recall, blue juice was stored in one or two locations, and ducted to each lavatory on demand. Compared to the traditional setup, where you've got a tank of blue goo under each toilet seat.
Vacuum lavs are a tremendous improvement for a variety of reasons, not the least of which is RELIABILITY. Especially at altitude, the system is basically infallible, unless you get a toilet base valve that won't close, and then you're in trouble.
But other than that, you're counting on the outside air pressure doing all the work for you- and that's pretty reliable!
Not to mention, blue water pump impellers? Do you REALLY have any desire to work on those? Trust me- not pleasant.
Mender From United Kingdom, joined Feb 2004, 250 posts, RR: 0
Reply 15, posted (5 years 1 month 2 days 17 hours ago) and read 5786 times:
Quoting readytotaxi (Reply 13): Okay, the toilet base valve won't close, what problems flow from that?
I guess the Lav is out of bounds, will it just keep sucking for the rest of the flight?
If the base valve is stuck open then you will not be able to generate a decent vacuum on that line. There are generally two main vacuum lines on the 767 so potentially half the toilets will be affected. Luckily I've managed to avoid working on the toilets on the 737NG but this might effect all of them!
vc-10 From United Kingdom, joined Oct 1999, 3720 posts, RR: 32
Reply 16, posted (5 years 1 month 2 days 6 hours ago) and read 5714 times:
Quoting Mender (Reply 15): If the base valve is stuck open then you will not be able to generate a decent vacuum on that line.
A more immediate problem is the noise in the cabin for the pax sitting around the affected lav. We ACARS the crew if that happens to wrap an orange in a blanket and place that in the bowl. The open valve is then plugged.
Other probs with Vac Lavs are blockages in the main line to the tanks. On our 747's there are some sharp bends in the pipes where thay go round the cargo door lift actuators. If pax have managed to put a nappy, a hand towl down the loo or the CC have put wine bottle corks and other stuff down there guess where all the stuff gets caught up. Then some lucky individual has to break down the pipes to find and extract the blockage
On the A340 system the main problem are the liquid level sensors in the tank. If they get contaminated by not being rinsed properly during toilet servicing they sense tank full, even though the tank may be empty, and shut down all the toilets that supply that tank. This problem can be overridden by pulling a few CB's, but it means if the toilet tank does subsequently become full the tank will overflow and you are left with skid marks on tail of ther aicraft where the vacuum outlets are